The hulls of all heavy cruisers of the Admiral Hipper type had bulbous formations in the underwater bow. The photograph of the cruiser Prince Eugene was taken on August 22, 1938, on the day the ship was launched. The bulb in the bow of the hull is clearly visible. It reduced wave formation, reduced hull resistance when the ship was moving, and increased the ship's stability on course. Despite the presence of a bulb and an “Atlantic” stem, the deck in the bow of the cruiser was heavily flooded with water when moving, even in relatively calm weather.
ADMIRAL HIPPER, 1939
PRINZ EUGEN, 1942
The heavy cruiser "Blücher" during trials in the Baltic Sea after repairs, the picture was presumably taken in March 1940. The stem is of the "Atlantic" type, the chimney is equipped with a visor, like on the pipe of the cruiser "Admiral Hipper". The Blucher is equipped with a FuMO-22 radar, the antenna of which is mounted on the front tower-like mast above the optical rangefinder.
Admiral Hipper-class cruisers
Heavy cruisers became a new type of ship that appeared as a result of the conclusion of the Washington 1922 and London 1930 naval agreements. These were ships with a displacement of 10,000 "long" tons (10,161 metric tons) and armed with 203 mm main guns. All the leading naval powers of the world - Great Britain, the USA, Japan, France and Italy - began building heavy cruisers. Germany remained constrained in its desires by the restrictions of the Treaty of Versailles. The Anglo-German Naval Agreement of 1935 allowed Germany to have a navy whose total tonnage would be 35% of that of the British navy. The agreement stipulated the tonnage, but not the class of ships, as a result of which Germany received the legitimate opportunity to build ships of any class, including battleships and heavy cruisers. According to the agreement, the Germans could build five “Washington” cruisers with a total displacement of 51,000 “long” tons. German representatives informed London that the construction of two such cruisers would begin immediately after the conclusion of the agreement. The first ship, the cruiser "H" ("ERSATZ HAMBURG") was laid down at the Blom und Voss shipyard in Hamburg 11 days before the formal signing of the Anglo-German naval agreement.
The specification called for the construction of a cruiser with a displacement of 10,000 “long” tons with a maximum speed of 33 knots, armed with eight to nine 152 mm guns, with adequate armor, and a calculated cruising range of 12,000 nautical miles (22,238 km). In terms of its characteristics, the German ship was very close to the French Alger-class cruisers and the Italian Zara-class cruisers, the newest at that time and the most successful ships of this class in the world. The Germans were unable to build complete analogues of the French and Italian heavy cruisers due to restrictions imposed on the ship's displacement. The designers again had to make compromises. The cruiser "N" (during the descent received the name "Admiral Hipper") and the cruiser "G" ("ERSATZ BERLIN" - "Blücher") turned out to be slower against the technical specifications, not so well protected by armor, the cruising range turned out to be significantly less than planned. All the shortcomings were a consequence of the need to fit into a predetermined upper displacement limit. "Admiral Hipper" entered service with the Kriegsmarine on April 29, 1939, "Blücher" - on September 20, 1939.
The ceremonial launching in Bremen on January 19, 1939 of the heavy cruiser Seydlitz, the second ship of the second group of heavy cruisers of the Admiral Hipper class. The Seydlitz was launched after the Prince Eugene and before the Lutzow. These three ships initially received extended "Atlantic" bows. The anchor will be released as soon as the ship hits the water to slow down the reverse movement of the hull after lowering. During the descent, larger anchors were used compared to the standard ones. The coat of arms of the Seydlitz family is fixed in front of the anchor fairlead, but before the “christening” of the ship the coat of arms is draped with fabric. Above the waterline, the cruiser's hull is painted in Schiffbodenfarbe 312 Dunkelgrau, below the waterline - in Schiffbodenfarbe 122a Rot. The stripe indicating the waterline is Wasserlinienfarbe 123a Grau.
The unfinished heavy cruiser "Lutzow" is being led by tugs to the Soviet port, April 15, 1940. Only the main caliber turret "A" is fully equipped and mounted; the 203-mm guns of this turret fired at the Nazi invaders during the defense of Leningrad.
"Admiral Hipper", just out of repair, in the ice of Kiel Bay. The stem on the ship was replaced; it became inclined, but still straight, and not rounded. A canopy is mounted on the chimney. A FuMO-22 radar antenna is installed above the optical rangefinder on the bow tower-like mast. At the beginning of February 1940, when the ice weakened, the cruiser moved to Wilhelmshaven.
The Kriegsmarine command ordered three more ships authorized by the Anglo-German treaty: the cruisers “J”, “K” and “L” (“Prince Eugene”, “Seydlitz” and “Lutzow”, respectively) in 1935 and 1936. By this time, ship designers could no longer pay attention to any contractual restrictions, so the ships turned out to be larger in size, and the displacement was increased by 1000 tons. The armor, armament and speed of the cruisers remained at the same level, but the cruising range increased by 14%.
"Admiral Hipper" takes on board the landing force, Cuxhaven, Germany. The landing force should be delivered to Trondheim as part of Operation Weserubung. The photograph was taken on April 6, 1940. Mountain rangers, with their unusual appearance, arouse genuine interest among the sailors from the cruiser’s crew, crowded around the railing of the ship’s deck. The upper parts of the main caliber towers are painted yellow. A 20-mm anti-aircraft gun is installed on the roof of the main caliber turret “B”.
Shipbuilding is one of the most complex areas of human activity. There are many different concepts in this area, the meaning of which is known only to professionals. One such term is "stem". This word can also be found in scientific and fiction literature when describing ships.
Meaning of the term
The stem is the front, strongest structure in the bow of the ship. It is represented by a steel beam, as well as a forged or cast strip, curved to the shape of the bow of the ship.
Depending on the conditions in which the vessel is operated, its speed and quality, the hull is given the appropriate shape. The stem is a kind of continuation of the keel of the ship. The transition to the keel line can be round, smooth or with a break. The shape of the stem creates a general impression of the ship itself. Even visually, a ship can be considered fast if it has a protruding stem. A photo of this part of the ship is presented in the article.
Functions
The stem is a part that in older types of warships was used as a ram against smaller ships. Submarines or destroyers could also perform a similar task. A ship equipped with a heavy stem is capable of breaking through the outer hull without serious damage: the hole is formed above the waterline.
Modern ships are equipped with stems that can even ram submarines, which are made from very thick steel sheets. Since the bow of a ship's hull is heavily impacted by wave impacts, the stems of non-combat ships must also be of very strong construction.
What types of stems are there?
When choosing one or another stem, the purpose of the ship and its shape are taken into account. The following types are used in shipbuilding:
- Leaned forward. In the underwater part, the stem at an angle meets the keel of the ship, which creates the impression of being directed forward. Due to such a stem, the vessel's ability to ride a wave is improved.
- Klipersky. Its shape is similar to an inclined stem. Applicable in
- The bulb-like stem of the boat in the surface part is represented by an inclined or concave line. The line under water has a teardrop shape. They are equipped with ships with a large hull width. By using such a stem, it is possible to achieve a reduction in wave resistance and an increase in speed. Since during pitching such a stem is highly susceptible to hydrodynamic effects, it is strengthened with the help of longitudinal and transverse stiffeners.
- Icebreaker. Ice-class vessels have such a stem. The line of this stem in the above-water part is slightly inclined forward. Closer to the surface of the water, the slope is 30 degrees. The same angle is maintained in the underwater part until the transition to the keel line. Ships equipped with such stems can easily sail on ice, pushing it with their weight.
- Straight. Under water it has a straight line that smoothly turns into a keel line. This stem is used by river vessels with free space on the deck that float on a calm water surface. The straight stem is convenient for viewing the space in front of the bow of the ship in places with narrowings and when approaching berths.
Execution options
These parts of the ships also differ from each other in design. The following types are used in shipbuilding:
- Bars. This design is considered the oldest. Today, tugs and small tugs with a timber keel are equipped with such stems. The stems in ice-class ships are equipped with special recesses (tongues) into which outer plating sheets are inserted. This design allows the vessel to maintain integrity in the event of damage.
- Cast. Unlike a timber stem, a cast stem with its cross-sectional shape is easily adjusted to the waterline. Due to the smooth connection of the sheets in front of the stem, the formation of water vortices is reduced. In order to increase the strength of cast stems, longitudinal and transverse stiffeners are used in shipbuilding.
- Sheet or welded. These stems are intended for large, fully welded ships with a bulb-shaped bow. In order to prevent deformation in the stem plates, horizontal spacer sheets are used, which in shipbuilding are known as bow bridges. With their help, the connecting joints between the stems and the sheets of the outer plating of the vessel are overlapped. A ship equipped with ice reinforcement has a longitudinal
Conclusion
Today in the field of shipbuilding, a bulb-like type of stem is more often used. The manufacturing technology of such vessels is more labor-intensive, which entails large financial expenses. But existing experience and the results of towing tests have shown that these ships have high speed and are safer.
The shape of the stem depends on the shape of the ship's bow (Fig. 1). Previously, ships were built with a vertical stem, but nowadays the slope of the stem to the vertical is 10-20°. Vessels intended for navigation in ice have a stem with a large undercut in the underwater part. The angle of inclination of the stem to the horizon on icebreakers is 20-30°, and on ice-going transport vessels 40-50°. This shape allows the icebreaker to crawl onto the ice. To increase speed, a drop-shaped thickening is made in the underwater part of the stem - a bulb, which reduces the resistance of water to the movement of the vessel.
Rice. 1 The bow of the vessel: a - straight; b - inclined; c - icebreaker; g - bulbous
The stem (Fig. 2) can be made in the form of a beam of rectangular or trapezoidal cross-section. To connect with the horizontal keel, the cross-section of the stem in the lower part gradually transforms into a trough-shaped shape. Recently, welded stems made of sheet steel have become widespread. The bow, curved from a thick sheet, is supported along its entire height by large horizontal brackets - breshtuk.
Rice. 2 Stem: a - bar (forged); b - sheet (svrioy); 1 — breshtuk The sternpost (Fig. 3) of a single-screw vessel with an unbalanced rudder is a frame consisting of two branches, the front one - the star post and the rear one - the rudder post. Between them a protected space is formed - an embrasure in which the propeller is placed. The starn post has a thickening with a through hole (the apple of the starn post) for the exit of the propeller shaft. The rudder post is equipped with loops for hanging the steering wheel, which have through cylindrical holes; in the lower loop - the thrust bearing - there is a blind hole into which a bronze or back-out bushing is inserted. The heel of the steering wheel in the thrust bearing rests on a hardened steel lentil.
Rice. 3 Sternpost: 1 - rudder post; 2 - star post; 3 - starn-post apple; 4 — thrust bearing; 5 — steering loops; I - loop, II - thrust bearing On twin-screw ships, the sternpost does not have a steering post and consists only of a rudder post on which the rudder is hung. On ships with a balance rudder, the sternpost does not have a rudder post.
The sternpost of sea vessels has a rather complex shape and design and is often cast with individual forged parts.
The upper part of the stern of modern ships usually looks like a flat vertical surface. This is the transom stern.
The propeller shaft on single-screw ships goes out through the stern tube (Fig. 4), which is attached at the bow end to the afterpeak bulkhead using a flange; the stern end passes through the star post and is secured with a nut. The stern tube can also be attached to the afterpeak bulkhead and star post by welding.
In the stern tube, the propeller shaft rests on bearings. Slider bearings with backout liners are used as stern tube bearings. Backout strips 1-1.5 m long are collected in a bronze bushing, which is pressed into the stern tube. A small gap is left between the strips, through which sea water flows to lubricate and cool the bearing. To prevent water from the stern tube from penetrating into the hull, a seal is installed at the bow end of the pipe.
Rice. 4 Stern tube: a - longitudinal section; b - stern tube bushing with a set of backout liners; 1 - star post; 2 - stern tube; 3 — aft stern tube bushing; 4 — bow stern tube bushing; 5 — stuffing box; 6 — afterpeak bulkhead; 7 - gasket; 8 — stern tube flange; 9 — oil seal pressure sleeve; 10 - propeller shaft; 11 — stern tube bearing shells For a set of stern tube bearings, instead of backout, its substitutes are used:
- Rubber-metal strips;
- Wood-laminated plastic;
- Textolite;
- Kaprolon.
Recently, the number of ships with babbitt stern tube bearings has increased significantly. These bearings require oil lubrication under pressure, so a special oil seal must be installed at the aft end of the stern tube.
On twin-screw ships, the propeller shafts exit through a mortar - a short pipe firmly attached to the hull. It has a stern tube bearing, which provides support for the propeller shaft, and an oil seal, which prevents water from penetrating inside the ship's hull.
After leaving the mortar, the propeller shaft is extended a certain length aft and is supported by a bracket directly at the propeller. On high-speed vessels and ice-going vessels, instead of a bracket, frame fillets are often installed. In this case, the contours of the stern part of the vessel are shaped in such a way that the propeller shafts can remain inside the hull of the vessel all the way to the installation site of the propellers.
The sides of the vessel are brought together at the ends, connecting at the stem and sternposts. In the stern, above the load waterline, a continuation of the sides is also a stern valance. The stem of most seagoing ships is mainly a forged or rolled steel beam of rectangular cross-section (see Fig. 56).Rice. 56. Stem.
Above the load waterline, the area of this section can gradually decrease, reaching 70% of the normal value at the upper end. If the stem, due to its large length, cannot be made at one time, then it is made composite of individual parts connected with the same lock that was shown for the timber keel. The same lock connects the stem to the beam keel, if the vessel has one. If the ship has a horizontal keel, the connection is usually somewhat more complicated. In this case, as can be seen in the same Fig. 56, at the stem, the lower part (sole) is made shaped, in the form of a special steel casting, attached with a lock to the rest of the stem. The shape of the stem sole, as can be seen in the figure, is such that gradually turning towards the bottom into a trough-shaped section, it allows for a gradual transition to a flat, horizontal keel. The first, the bow sheet of the horizontal keel, receiving the corresponding trough-shaped shape, covers the end of the stem from below and, riveted with it, thus provides the required connection between the stem and the keel. The stem sole usually extends to the collision bulkhead and in the forepeak it is also connected to the previously mentioned vertical keel brackets. For this purpose, in the casting of the stem sole is made vertical longitudinal rib. U modern On very large ships, the stem sometimes takes on a much more complex shape. Firstly, due to its large size, it has to be made of cast steel, as can be seen in Fig. 57;
Rice. 57. Cast stem.
at the same time, like a casting, it acquires a trough-shaped shape along its entire length. The same trough-shaped, forged short extensions are placed on the stem locks to cover them (Fig. 58). A trough-shaped casting for greater strength is made with a number of horizontal ribs inside. The locking connection of the individual cast parts that make up the stem is made of a bolted, flange type (see Fig. 58).
Rice. 58. Cast stem lock.
In its lower part, as can be seen in Fig. 59, modern stems are beginning to be given a pear-shaped, or rather “bulb” shape, in order to achieve better streamlining of the bow end of the vessel with water dissected by the lower part of the stem during the course. The sternpost of the vessel has a more complex shape than the stem. This is due to the fact that there is an outlet the ship's propeller shafts with propellers located at the ends of the latter, and the ship's rudder is also hung here. The design of the stern post therefore receives a close connection with these devices and, depending on the nature, receives a different appearance. Therefore, first we will consider the location of these devices in the stern of the ship. As for the output of the propeller shafts and the location of the propellers, here it is necessary to distinguish between two main cases: a ship with an even number of propeller shafts (and with it propellers) and with an odd number. In the simplest form for our consideration, this comes down to the cases of a single-screw and double-screw boat In a single-screw vessel, the propeller shaft is located in the centerline plane of the vessel and, therefore, its axis lies in the plane of the sternpost; The sternpost must be so designed as to provide space for the end of the propeller shaft to exit the hull and for the location of the propeller at that end.
In a twin-screw ship, the propeller shafts pass on both sides at a certain distance from the centerline of the ship, sufficient so that when the propeller shaft leaves the ship’s hull, the propeller mounted on the end of this shaft can rotate freely without touching the ship’s hull. For the latter purpose, in addition to a sufficient distance between the shaft axis and the center plane, there is also a need for a sufficient offset of the end of the shaft back to the stern from the point where it exits the ship’s hull. In the case of a twin-screw vessel, as can easily be imagined, there can be complete independence between the sternpost (located in the centerline plane) and the propeller shaft outlet device and the position of the propeller (located away from the centerline plane). However, as we will see, this does not always happen and often a connection is established between them.
Rice. 59. The bow of the ship with a cast stem.
Rice. 60. Ordinary sternpost and rudder.
We will further dwell on the design of the place where the propeller shaft itself exits from the ship’s hull.
As for the structure of the rudder, the latter of a sea vessel is always located in the center plane and is suspended directly on the sternpost. It affects the shape of the sternpost depending on its design, namely, depending on whether we are dealing with a rudder of a conventional design, the plane of which is on one side of the axis of its rotation, or with a rudder balancing type, in which a certain part of the plane is also located in front of its axis of rotation (the advantage of a steering wheel of this type is that it makes it easier to rotate around its axis). The balance-type rudder, by its design, can be of two types, which influence the shape of the sternpost, namely: it can have only the lower part of its plane protruding forward from the axis of rotation, or it can have a part of its plane protruding forward along its entire height. The rudder of the latter type, of course, cannot be suspended from the sternpost on hinges, which, on the contrary, is mainly the case with all other types of rudder.
Rice. 61. Balance-type steering wheel.
All of the above combinations of rudder devices and the arrangement of propellers and propeller shaft outputs can be seen more clearly in Fig. 60-66. All possible other combinations of these devices can be easily imagined based on these same drawings.
1) In Fig. 60 shows the stern of a single-screw vessel with a simple rudder hinged to the sternpost; There is a clearance in the sternpost to accommodate the end of the propeller shaft with the propeller.
2) In Fig. 61 the lower part of the stern of the same single-screw vessel is visible, the rudder of which, however, rotates around an axis (shown by the dotted line), so that part of the rudder at its entire height is in front of the axis of rotation (balance-type rudder).
3) In Fig. 62 shows the lower part of the stern of a three-screw vessel, in which one screw is located in the center plane, while the other two (one left screw is visible in the figure) are located on the sides; the rudder of this vessel, like balapser rudders, is suspended on hinges, having only part of its lower area protruding forward; the sternpost must have a complex figured shape.
4) In Fig. 62 a twin-screw ship with the same rudder located on a slipway is photographed; the design of the exit of the left propeller shaft from the ship's hull is clearly visible in the foreground of the photo.
Fig. 62 The stern of a three-byte vessel with a semi-balanced rudder.
5) In Fig. 64 shows the rudder of a simple type of two-screw ship, suspended on hinges. To support the propeller shafts coming out of housing vessels with a large offset at the propeller have a special outer bracket.
Rice. 63. The stern of a twin-screw vessel with a semi-balanced rudder.
6) In Fig. 65, the exits of the propeller shafts with propellers of a large four-screw ship are visible (two right shrouds are visible in the figure; two similar propellers are located on the other side of the ship).
Rice. 64. Stern of a twin-screw vessel with an external bracket.
7) Finally, in Fig. 66 shows the steering frame (not yet covered with sheets) of a balaisir-type steering wheel without hinges. A rudder of this type is often used on a two-screw vessel or a four-screw vessel shown in the previous figure; the sternpost in this case takes on a completely unique shape.
Rice. 65. The output of the propellers of a four-screw ship.
Rice. 66. Sternpost with balance rudder.
Moving on to the consideration of the design of the sternposts themselves, we must first of all note that only very small seagoing ships have sternposts made forged; usually, due to their complex shape, they have to be made of cast steel, made up of separate parts. These parts are connected with locks of the same type as those discussed at the stems. However, due to the fact that the sternpost has to take the work of the propeller shaft, these locks are made somewhat more solid.
Rice. 67. Sternpost of a single-rotor ship.
The simplest form is the stern post of a small twin-screw vessel. This form differs from the stem only in that its horizontal and vertical branches converge at right angles and the vertical branch is equipped along its height, from the bottom to the stern valance, with loops for hanging the rudder on the sternpost, and at the bottom with a heel for supporting the latter. To avoid damage to the rudder when the bottom of the vessel comes into contact with the ground, it is recommended to always make the heel of the rudder slightly raised against the keel line. The loops and heel must be made integral with the stem. The sternposts are connected to the keel in the same way as was indicated for the stems, and for better connection with the hull of the vessel, the sole of the sternpost should have a length of at least 8 times the width of its body (usually 4-5 spacing). The upper branch of the sternpost, rising upward, enters the stern valance and here, inside the vessel, is firmly riveted to the transom bulkhead.
In large twin-screw ships and especially with semi-balanier rudders, the sternpost, if it is independent of the output of the propeller shafts, receives a slightly more complex form of steel casting, similar to the casting shown in Fig. 66. The designs of these sternposts are independent of the exit of the propeller shafts from the vessel. If the sternpost of a twin-screw vessel is connected to the output of the propeller shafts, then its shape turns out to be extremely complex. Therefore, first we will look at the stern post of a single-screw vessel. This stern post is inevitably connected with the output of the propeller shaft. Therefore, its shape takes the form shown in Fig. 67, and in a lying state (manufactured) - in Fig. 68. Here the sternpost already forms a frame, as it were, inside which the propeller is located.
Rice. 68. Photograph of the sternpost of a single-rotor ship.
Rice. 69. Stern tube with mortar, (twin-screw vessel).
Through the front part of this frame, called senior post, the end of the propeller shaft enters this frame, for which a corresponding hub is installed in the star post (visible in the foreground near the lying sternpost). This hub (often called the apple) from inside the ship includes the end of the stern tube through which the propeller shaft is removed from the ship's hull. This pipe passes through the afterpeak, securing its opposite end to the afterpeak bulkhead. Thus, the propeller shaft from the engine goes through the propeller shaft tunnel, then through the stern tube and finally comes out (see Fig. 69). The second part of the stern post frame (Fig. 67), on which the rudder is hung, is called the rudder post and it is similar to the same part of the stern post of a twin-screw vessel. For greater connection of the stern post with the hull of the vessel, in addition to the previously indicated connection of the upper part of the ruder post with the transom bulkhead, the stern post usually also has in its upper part a branch entering the interior of the vessel, which inside the vessel is connected to a specially reinforced floor located in the stern peak - above the stern post frame ( see Fig. 67, 70, 71).
Rice. 70. Sternpost with triangular cross-section.
The sections of the sternpost frame parts are usually made rectangular; the heel between the star post and the ruder post is made flatter and wider. The upper parts of the sternpost branches usually have flanges for better connection inside the vessel to the transom bulkhead and floor.
Recently, sternposts of single-rotor ships have begun to be manufactured, as shown in Fig. 70, with a triangular cross-section of the star post, pursuing the goal of better flow around it with jets of water during propeller operation.
The somewhat special shape shown in Fig. 71, has the stern post of a single-screw vessel equipped with the previously mentioned balancing rudder rotating around an axis. This axis in this case, as can be seen in Fig. 71, replaces the usually existing rudder post. The steering wheel bearings surround this axis, and the steering wheel can thereby rotate around it. We do not dwell on the special design of the rudder itself, which has a fish-shaped cross-section (for the purpose of also making it more streamlined), since consideration of rudders related to the equipment of the vessel (ship devices) is not part of our task.
The cross-section of the sternpost branches above the stern valance can gradually decrease, reaching at the upper end up to 50% of their normal cross-section below, at the valance.
Rice. 71. Sternpost without rudder post.
Now let's return to the consideration of the sternposts of twin-screw ships. As we noted above, in these ships the sternpost has a more or less simple shape only if the output of the propeller shaft is completely unconnected with the sternpost.
Let's consider the design of the propeller shaft output. In this case, the propeller shaft also passes through the afterpeak in the stern tube. For small ships, the end of the stern tube coming out of the hull is fixed to the outer hull of the ship in a special holder (cast steel and forged), called mortar propeller shaft. It is shown in Fig. 72. The rowing Bal's mortar, being well connected to the corresponding transverse frame of the vessel, is a solid support for the end of the stern tube. The ship's plating sheet covers the mortar and is fastened to it watertight by means of rivets and goujons. The propeller shaft coming out of the mortar at the place where the propeller is placed on it at the end, as mentioned earlier (see Fig. 64), is supported by a special bracket propeller shaft. This bracket, located on the outside of the boat, consists of a hub that wraps around the end of the shaft and two posts extending from the hub.
Rice. 72. Mortar of the propeller shaft.
These racks, if possible, go at an angle close to 90° to each other and are riveted to the hull of the vessel with the claws at their ends (usually on top of the outer plating).
Rice. 73. Cast propeller shaft bracket.
The ship's hull at this point is properly reinforced from the inside. The lower foot rests mainly on the sole of the sternpost. In order for the bracket protruding outside the vessel to cause as little resistance as possible when the vessel moves, its struts are given a streamlined cross-section (such a cross-section is given to the rudder we met earlier, as well as in the aircraft industry - to the wings of airplanes).
Rice. 74. Set of the stern of the ship.
However, the same design of the bracket protruding outward, both from this point of view and from the side of the fortress, is unacceptable for large seagoing two- and four-screw vessels. Therefore, in such ships, the propeller shaft bracket, of a more solid design (in the form of special castings), is placed inside the ship’s hull. For this purpose, the bracket is made of the type shown in Fig. 73, cast as two branches at once for the starboard and port shafts, with a sufficiently large reach so that the propellers can fit outside the vessel in close proximity to the bracket. All the frames of the ship, going forward from this bracket, are made of a special shape (see Fig. 74), thanks to which it is possible to carry out the outer plating of the ship right up to the bracket. The ship's hull then receives a smooth ledge, visible in Fig. 63 and fig. 65, inside which the stern tube passes and at the end of which, directly outside, the propeller is placed.
Rice. 75. View of the sternpost of a large twin-screw ship.
This will always achieve significantly better streamlining of the ship's hull in the area where the propeller shaft exits, with a very strong support for the end of the propeller shaft. Modern large seagoing vessels with two and four screws all have such an output of propeller shafts. At the same time, inside the ship’s hull, the brackets can still receive a direct connection with the sternpost, as can be seen in Fig. 75, which shows, together with brackets, the sternpost of a vessel of the type that was previously shown in Fig. 63.
An even more solid connection is obtained with the sternpost design shown in Fig. 76; the design of such a sternpost in its manufactured form is clear from Fig. 77.
Above the sternpost and rudder, the ship's stern valance protrudes above the load waterline, and when the stern is cruising, this valance is submerged in the water slightly below the load waterline (Fig. 2).
Rice. 76. The design of the sternpost of a large twin-screw ship.
The design of the stern valance is also made up of frames and beams, and in the cruising stern they are usually similar to the frames and beams in other parts of the ship.
Rice. 77. Photograph of the sternpost of a large twin-screw ship.
Rice. 78. Set of the stern of the ship.
With the usual form of stern valance, the frames and beams are always arranged in a fan-shaped manner ( radial or rotary), based on the transom bulkhead, as can be seen in Fig. 78. They are attached to the transom bulkhead with brackets. Through the stern valance along the transom bulkhead in the center plane there is a vertical semicircular or square section helm pipe, coming from below and reaching one of the decks of the ship (lower or upper) in the stern valance. This pipe is carried inside the ship to this deck rudder stock, i.e. that upper, circular section, part of the rudder, which turns the rudder (using a special mechanism installed nearby on this deck).
4. The outer plating of the vessel and the second bottom flooring.
The outer plating of the vessel creates its waterproof shell and at the same time gives the necessary strength to the vessel. The outer plating consists of the remaining sheets riveted to the frames and stringers, and these sheets are located in their grooves along the ship; the sheets connected by joints to one another form sheets running along the length of the vessel belts external cladding. Individual outer skin belts have different names. The bottom belt, intersected by the center plane, is, as we know, called the horizontal keel. If there is a timber or layered keel, a bottom belt, called sheet piling, is adjacent to it on one side and the other. The remaining bottom belts are called bottom belts of the outer skin. It goes along the cheekbone zygomatic girdle and above it - row of side belts. The upper side plating chord adjacent to the upper continuous deck is called shearstrake, and the belt below it is often called waist below shearstrake. The side plating belts go further to the superstructures, and the upper belt will be Shirstrek add-ons. The belt between the superstructures along the side, above the upper deck, is called bulwarks.The thickness of the sheets of individual belts is taken to be different: firstly, we have already seen, the thickest is the horizontal keel belt, as well as the shearstrake belt; the bottom girdles, including the zygomatic girdle, have the same thickness; The side flanges also have the same thickness, usually somewhat smaller than the bottom flanges, with the exception of the belt below the shearstrake, the thickness of which is intermediate between the thickness of the shearstrak and the thickness of the side sheathing flanges. As you approach from the middle of the ship to the ends, the thickness of the sheets of each belt (outside the middle half of the ship) gradually decreases to a certain value. In this case, however, the three belts of the bottom plating, adjacent on both sides to the horizontal keel, must retain, right up to the collision bulkhead, the thickness that they have in the middle part of the vessel. In the same way, the plating sheets adjacent to the sternpost and to the exit points of the propeller shafts must maintain a thickness corresponding to the thickness in the middle part. If significant cuts are made in the side plating of the ship, then these cutouts must be compensated by thickening, plating, introducing overlay sheets, etc. methods.
The thickness of all outer plating chords must be increased if the ship's frame distances are increased compared to normal. For ships intended to navigate in ice, special thickening of the bow end sheets in the area of the load waterline is required.
Of particular importance in relation to the longitudinal strength of the vessel is the shearstrake belt, as it is the most distant of all the side belts from the neutral plane of the vessel. In this regard, the following feature is provided in the design of this belt. As we know, the long middle superstructure of a ship can participate in the longitudinal strength of the ship. In the case of a long middle superstructure, its shearstrake, being even more distant from the neutral plane than the shearstrake of the upper deck, will take an even greater part than the latter in the longitudinal strength of the ship. From these considerations, the following is provided: with long middle superstructures, the belt at the upper deck in the area of the superstructure, except for its ends, does not thicken, but has the same thickness as the rest of the side belts; The shearstrake is placed near the deck of the superstructure. At the same time, the shearstrak of the superstructure has a thickness less than that required for the shearstrak of the upper deck. To compensate for the sharp change in the cross-section of the longitudinal connections of the hull at the ends of the middle superstructure, the following reinforcements are provided here: the shearstrake of the upper deck does not break off immediately at the superstructure, but extends beyond it over an extent equal to a third of the width of the vessel. In this case, the thickness of the shearstrak sheet of the upper deck at the ends of the superstructure is made 50% thicker than the adjacent sheets of shearstrak; This thick sheet of shearstrake must extend at least 3 spaces inward and 3 spaces outward beyond the end of the superstructure.
Also, the lower plating belt of any superstructure extends beyond the ends of the superstructure by at least 3 grooves, smoothly transitioning into the bulwark belt (thinner than the superstructure plating sheets). Reinforcements similar to those indicated are also made at the ends of the long forecastle and poop (the length of which exceeds a quarter of the length of the vessel). The thickness of the outer plating sheets of the vessel (and superstructures) is taken depending on the length of the vessel, its draft and the height of the side to the upper deck (and to the superstructure deck).
To avoid weakening the longitudinal strength of the ship, the joints of nearby belts of the outer plating of the ship should not come close to each other. For spacing the joints of the chords in the outer cladding, there is the following rule: the joints of the sheets of two adjacent chords must be separated from each other by at least two spacings. The joints of sheets of belts located across one belt should not be in the same space. However, the last paragraph does not apply, for the sake of the possibility of maintaining a symmetrical arrangement of joints for the right and left halves of the vessel, to sheet piling belts and belts adjacent to the horizontal keel. Riveting of grooves and joints of the outer skin, as mentioned earlier (Chapter Ill), is done using a chain seam, and the number of rows of rivets in the joints exceeds the number of rows of rivets in the grooves, especially at the bottom, shearstrake and the belt under it. However, the sheathing sheets are attached to the stems (and to the outer keel) with a checkerboard seam.
The width of the plating belts: the horizontal keel, the shearstrake, the belt under it and the bilge belt is maintained constant along the entire length of the vessel. They also try to maintain the width of the remaining belts without large reductions, however, as we will see below, it is not possible to comply with this condition for all belts along the length of the vessel.
First, let us consider a very important issue about the method of attaching the outer skin chords to the transverse structure of the vessel (frames and floors). The grooves of the outer skin belts are currently connected only in exceptional cases using butt strips. The groove connections currently used are overlapping with or without flanging, and we rarely see the first of these methods. With this method, either one edge of each belt can be flanked (one-sided flanking), or not all belts can be flanked, but through one, but in this case, the flanked belt must receive flanging along both edges (two-sided) (see Fig. 79) . Double-sided flanging has production advantages, since it requires only half of all sheathing sheets to be fed under the machine, but from the operational side, one-sided flanking of the belts has advantages, since in this case, when repairing and changing sheathing sheets, each sheet can be easily removed from its place. With double-sided flanking, the sheets of an unflanked belt can be removed only after unfastening the sheets of one of the adjacent belts. When using riveting of overlapping grooves without flanging, in order to rive the sheathing sheets to the frames or floors, it is necessary to place a wedge gasket along the profile flange, between the sheet and the flange, as can be seen in Fig. 79. Currently, a similar method of connecting grooves is used abroad, but without gasketing, which is achieved by appropriately setting up a profile to which the sheet is riveted (this method of connection is shown in Fig. 80 in riveting the second bottom flooring sheets to the floras); landing of the profile is convenient for small sizes of this profile. Noteworthy is the method of riveting the outer skin to the floors, shown in the same figure, where both the landing of the profile and the use of gaskets are avoided. True, this method has not received recognition from classification institutions.
Rice. 79. Side trim grooves.
The connection of grooves on the internal joint strips is carried out only in exceptional cases, when it is necessary to obtain a completely smooth surface on the outer hull of the ship. This occurs, for example, with icebreakers. In this case, gaskets are also placed along the frame or floor, or the profile is upset, as indicated above.
As for the joints of the sheets of outer skin chords, these joints occur between the frames or floors. Therefore, there is no difficulty in making them both on internal butt strips and with overlaps. In the latter case, the overlap should be done so that the outer covering sheet does not have an edge directed towards the bow, i.e., against the movement of the vessel.
Currently, overlapping joints of external cladding are more often used; There are indications that such a butt seam, when stretched, retains impermeability better than a butt seam with an ordinary internal strip, while providing savings in material.
Very important in the design of the outer skin is the mating of the groove with the joint. The simplest way is to use a wedge-shaped gasket along the groove in this place, shown in Fig. 81.
Rice. 80. Set of flora with a planted reverse square.
However, this design is now more often replaced by appropriate stitching caresses at the corner of the sheet, as can be seen in Fig. 82. Gouging the edge of a sheet is now used when passing a profile across a groove (or joint) of a sheet. Such stitching is shown in Fig. 83. Along it, the profile smoothly passes through the groove, requiring neither upsetting nor the use of a wedge-shaped gasket.
Rice. 81. Installing a wedge-shaped gasket.
The design of the outer plating of the vessel is represented by a special drawing, in which the plating is depicted in the form of a so-called stretch marks(see appendix 2). This guy line drawing is obtained by unfolding each frame (and floor) of the vessel in a straight line. Since the length of each of these lines depends on the contours of the hull and turns out (due to the shape of the vessel tapering towards the extremities) to vary along the length of the vessel, the plating, when stretched in this way, takes on a figured appearance, as can be seen from the above figure. It should be borne in mind that stretching of the skin is usually carried out, as is done in this figure, only in one direction, namely transversely (along the frames and floors), but not along the length (not along the waterlines). Thus, in the drawing of the outer cladding, without distortion in actual form, the width of the sheets is given, but not their length, which in reality will be somewhat greater than it is shown in the drawing.
Rice. 82. "Weasel."
Rice. 83. Sheet stitching.
Considering the width of the sheets of individual outer skin chords, we see that due to the reduction in the contours of the vessel towards the extremities, it is not possible to have all the skin chords at the bow and stern of the same width as they have in the middle part.
Rice. 84.
Rice. 85.
Leaving the width of the horizontal keel belts, the shearstrake and the belt under it, as well as the bilge belt unchanged, in order to obtain the required type of stretch, we would have to lead all other outer skin belts to the ends gradually and evenly tapering down to the stem. Such a design, however, would be quite complex in production terms. Therefore, the belts of the outer cladding sheets are designed somewhat differently, as can be seen in the same figure. Namely, the width of the sheets for most outer cladding belts is kept constant. Some belts (usually a small number of them are sufficient for this purpose) are made to sharply taper towards the ends of the vessel, to the point that these belts are finally cut off between adjacent belts adjacent to them, without bringing such tapering belts to the stems. Consequently, in some places of the skin some belts disappear; such places are called losses these belts.
The design of the loss can be different and some variants of these designs, the most common ones, are given in Fig. 84-86.
Rice. 86.
Another feature in the design of the ship's outer plating is of some interest. It is as follows: in addition to the transverse braces of the vessel, to which we have just discussed the attachment of the outer plating, inside the vessel there is a number of longitudinal braces, which in some cases are also riveted to the outer plating. These connections are usually located in such a way that the connection runs along the corresponding belt of the outer skin, without leaving it and on its way crossing only individual joints of the sheets of this belt. This arrangement can usually be maintained in relation to all longitudinal connections, with the exception of one - the zygomatic stringer (the outermost double-bottom sheet). The zygomatic stringer, due to its position on the bilge of the ship, which we previously discussed in detail, cannot run along its entire length along the zygomatic belt of the outer plating of the ship alone. Approaching the ends of the vessel, it begins to descend from the zygomatic belt onto the adjacent belt, thus crossing the corresponding groove of these belts and, moreover, at a rather acute angle. The passage of the lower square of the outer double-bottom sheet along the groove of the outer skin is in itself quite inconvenient; in this case, it is further complicated by the fact that both the riveting of the groove and the riveting of the square of the double-bottom sheet are especially important in terms of their waterproofness.
To obtain waterproofness both along the groove and at the square, the design shown in Fig. 87, where the arrangement of rivets along the groove and the arrangement of rivets along the square can be done with the frequency required for both, ensuring their waterproofness.
Rice. 87. Intersection of a square with an impenetrable groove.
In addition, the very transition of the square through the protruding edge of the groove can be made conveniently feasible. With this design, the outer skin, as can easily be seen in Fig. 87, in the place under consideration receives a characteristic feature in the form of a short tooth at the groove of the zygomatic girdle and at the bottom girdle adjacent to the latter.
Rice. 88. Intersection of a square with an impenetrable groove by welding a strip.
However, since the construction of such a tooth requires significant cutting of the sheet, recently, in connection with the use of electric welding, they very often resort to a simplified design, limited, as shown in Fig. 88, by local widening of the horizontal flange of the square of the outer double-bottom sheet in the area where this square passes through the groove. This widening is achieved by welding small pieces of sheet to the flange of the square, which makes it possible to place a sufficient number of rivets in this place, which ensures sufficient density of both the riveting of the groove and the density of the riveting of the square along the outer skin.
With this said, we will finish our consideration of the outer plating of the ship.
Device flooring of the second bottom made easier by the fact that, as we know, the surface of the second bottom is usually horizontal. We have already discussed the design of the outermost double-bottom sheet and its features. The remaining sheets of flooring are usually laid along the ship, forming a series of belts. At the ends, where the width of the second bottom decreases, the belts adjacent to the outermost double-bottom sheet are cut at an angle, along the direction of the double-bottom sheet, to form a seam with this sheet.
In the center plane of the vessel, along the entire flooring there is a middle belt, the thickness of which is taken to be greater than the thickness of the other belts. In general, the thickness of the sheets of both those and other belts is assigned depending on the length of the vessel and the distance between the frames.
In the area of the engine room, all flooring sheets must have a thickness equal to the thickness of the middle chord; in the area of the boiler room, all sheets receive an even greater increase in thickness. In the same way, those sheets of steel flooring of the second bottom in cargo holds that fall under the clearance of the cargo hatches thicken, if these sheets are not protected by additional wooden flooring placed in the hold on top of the steel one. Particular thickening of the decking sheets is done in the engine room in cases where the ship's engine frame is installed directly on the second bottom decking without installing a special foundation for the engine on the decking.
In places where the ship's transverse bulkheads pass along the second bottom flooring, it is allowed, as an exception, to place sheets of flooring under the bulkhead - across the ship, and, however, the middle belt and the outer double-bottom sheet must retain their longitudinal position in this place. The transverse arrangement of the flooring sheets under the bulkhead provides production advantages when installing the lower lining of the bulkhead.
Sheets of flooring on the second bottom are almost always joined side by side, and usually with flanking; Along with this, the possibility of using other connection methods, including the one shown earlier in Fig. 80.
The joints of the flooring sheets are made stronger than the grooves. The above applies especially to the joints of the middle belt and the outer double-bottom sheet. The mating grooves and joints have the design mentioned earlier when considering the outer plating of the ship.
Rice. 89. Layout of steel deck flooring.
To access the double-bottom space, manholes are installed in the flooring of the second bottom, at least 2 in number for each separate compartment of the double bottom, and if possible they should be located at opposite ends of the compartment. The dimensions of the necks should be sufficient for ease of climbing into them. The necks are closed with special waterproof caps. The dimensions of the necks (as well as the design of their lids) are standardized. Covers must be protected from the possibility of damage when loading heavy cargo into the hold.
(3) The design of the stern tube is such that it does not allow sea water to penetrate into the vessel through it, while the propeller shaft freely exits through it (thanks to the stuffing box system) and rotates freely in it.
The bow and stern ends of the ship's hull are limited and supported by the stem and stern stem, respectively. The stem and sternpost (Fig. 5.24, 5.25) are connected by welding to the outer plating, with a vertical and horizontal keel, high floors, side stringers, and platforms. Thus, a powerful structure is formed that can withstand significant loads that arise during the operation of the vessel (impacts on ice, floating objects, contact with the pier and other ships, loads from a working propeller, etc.).
Since the bow and stern ends of the vessel experience significant additional loads from wave impacts, the so-called. “slamming”, these areas of the vessel are reinforced by reducing spacing, additional side and bottom stringers, platforms, high floors, and frame frames.
| |
Fig.5.24. The stem is welded.
1 – breshtuk, 2 – longitudinal stiffener rib
SHIP DEVICES
Anchor device
The anchor device is designed to ensure reliable anchorage of the vessel in the roadstead and at depths of up to 80m. The anchor device is also used when mooring to a pier and unmooring, as well as to quickly absorb inertia in order to prevent collisions with other vessels and objects. The anchor device can also be used to refloat a vessel. In this case, the anchor is transported on a boat in the desired direction and the ship is pulled towards the anchor using anchor mechanisms. In some cases, the anchor device, as well as its elements, can be used to tow a vessel.
Seagoing vessels usually have a bow anchor device (Fig. 6.1), but some ships also have a stern one (Fig. 6.2).
The anchor device usually includes the following elements:
- anchor, which, due to its mass and shape, enters the ground, thereby creating the necessary resistance to the movement of a ship or floating object;
- anchor chain, transmitting force from the vessel to the anchor located on the ground, is used for recoil and lifting of the anchor;
- anchor hawse, allowing the anchor chain to pass through the elements of the hull structures, directing the movement of the ropes when releasing or retrieving the anchor, the anchors are pulled into the fairleads for storage during travel;
- anchor mechanism, providing release and lifting of the anchor, braking and locking of the anchor chain when anchored, pulling the vessel towards the anchor fixed in the ground;
- stoppers, which serve for fastening the anchor in a traveling manner;
- chain boxes for placing anchor chains on a ship;
- mechanisms for fastening and remote release of the anchor chain, ensuring fastening of the main end of the anchor chain and its rapid release if necessary.
Anchors depending on their purpose they are divided into deadlifts designed to hold the vessel in a given place, and auxiliary– to hold the vessel in a given position while anchored at the main anchor. The auxiliary ones include a stern anchor - a stop anchor, the mass of which is 1/3 of the weight of the anchor and the rope - a light anchor that can be carried away from the ship on a boat. The mass of the verp is equal to half the mass of the stop anchor. The number and weight of main anchors for each vessel depends on the size of the vessel and is selected according to the Rules of the Register of Shipping.
The main parts of any anchor are the spindle and claws. Anchors are distinguished by mobility and the number of arms (up to four) and the presence of a rod. Clawless anchors include dead anchors (mushroom-shaped, screw, reinforced concrete) used when installing floating lighthouses, landing stages and other floating structures.
There are several types of anchors that are used on sea vessels as anchors and auxiliaries. Of these, the most common anchors are: Admiralty (previously used), Hall (obsolete anchor), Gruson, Danforth, Matrosov (installed mainly on river vessels and small sea vessels), Boldt, Gruzon, Cruson, Union, Taylor, Speck, etc. .
The Admiralty anchor (Fig. 6.3a) was widely used during the sailing fleet, due to the simplicity of its design and high holding force - up to 12 anchor weights. When pulling the anchor, due to the movement of the vessel, the rod lies flat on the ground, and one of the legs begins to enter the ground. Since there is only one paw in the ground, when the direction of tension of the chain changes (yaw of the vessel), the paw practically does not loosen the soil and this explains the high holding force of this anchor. But it is difficult to remove it while on the move (due to the stem it does not fit into the hawse and has to be put away on the deck or suspended along the side), in addition, in shallow water the foot protruding from the ground poses a great danger to other ships. The anchor chain may get tangled in it. Therefore, on modern ships, Admiralty anchors are used only as stop-anchors and ropes, in the occasional use of which its disadvantages are not so significant, and a high holding force is necessary.
The Hall anchor (Fig. 6.3 b) has two swivel legs located close to the rod. When the vessel yaws, the paws practically do not loosen the soil, and therefore the holding force of the anchor increases to 4-6 times the gravity force of the anchor.
The Hall anchor meets certain requirements: 1) it releases quickly and is conveniently fastened in a traveling manner; 2) has sufficient holding force with less weight; 3) quickly picks up soil and is easily separated from it.
The anchor consists of two large steel parts: a spindle and arms with a head part, connected by a pin and locking bolts.
This anchor does not have a rod, and when retracting, the spindle is pulled into the fairlead, and the legs are pressed against the body. Among the large number of anchors without a rod, the Hall anchor is distinguished by its small number of parts. Large gaps at the joints of the parts eliminate the possibility of jamming of the paws. When falling on the ground, thanks to the widely spaced paws, the anchor lies flat and when pulled, the protruding parts of the head part force the paws to turn towards the ground and enter it. Burying itself into the ground with both paws, this anchor does not pose a danger to other vessels in shallow water and eliminates the possibility of the anchor chain getting tangled in it. But due to the fact that two widely spaced paws are in the ground, when the ship yaws, the soil loosens and the holding force of this anchor is much less than the Admiralty anchor with one paw in the ground.
The Danforth anchor (Fig. 6.4) is similar to the Hall anchor; it has two wide, knife-shaped swivel legs located close to the rod. Thanks to this, when the vessel yaws, the paws practically do not loosen the soil, increasing the holding force of the anchor by up to 10 times and its stability on the ground. Thanks to these qualities, the Danforth anchor is widely used on modern sea vessels.
Fig.6.4. Dumforth Anchor
Matrosov's anchor has two swivel legs. In order for the anchor to lie flat on the ground in all cases, there are rods with flanges in the head part of the anchor, and after being pulled by the ship, the anchor lies flat and, thanks to the protruding parts of the head part, the legs rotate and enter the ground. Matrosov's anchor is effective on soft soils, which is why it has become widespread on river and small sea vessels, and its high holding force makes it possible to reduce weight and make the anchor not only cast, but also welded.
On small ships and barges, multi-legged rodless anchors called cats are used. Ice navigation vessels are equipped with special single-arm rodless ice anchors designed to hold the vessel near the ice field.
anchor chain serves to attach the anchor to the ship's hull. It consists of links (Fig. 6.5), forming bows, connected to one another using special detachable links. The bows form an anchor chain with a length of 50 to 300 m. Depending on the location of the bows in the anchor chain, there are anchor (attached to the anchor), intermediate and main bows (attached to the hull of the vessel). The lengths of the anchor and main bows are not regulated, and the length of the intermediate bow, which has an odd number of links, is 25–27.5 m. Attach the anchor to the anchor chain using an anchor shackle. To prevent the chain from twisting, rotating links - swivels - are included in the anchor and main bows.
Anchor chains are distinguished by their caliber - the cross-sectional diameter of the link bar. Chain links with a caliber of more than 15 mm must have spacers - buttresses. On the largest ships, the caliber of anchor chains reaches 100-130mm. To control the length of the etched chain, each bow at the beginning and end has a marking indicating the serial number of the bow. The markings are made by winding annealed wire around the buttresses of the corresponding links, which are painted white.
Anchor hawse perform two important functions on ships - they ensure unhindered passage of the anchor chain through the hull structures when releasing and retrieving the anchor and ensure convenient and safe placement of the rodless anchor in the stowed position and its quick release. Anchor fairleaes consist of a fairlead pipe, a deck fairlead and a side fairlead.
The hawse pipe is usually made of steel welded from two halves (in diameter), and the lower half of the pipe is thicker than the upper, since it is subject to greater wear by the moving chain. The internal diameter of the pipe is taken to be equal to 8 - 10 chain gauges, and the wall thickness of the lower half of the pipe is in the range of 0.4-0.9 chain gauge.
Side and deck hawsees are cast steel and have thickenings where the chain passes. They are welded to the hawse pipe and welded to the deck and side. The anchor spindle fits into the pipe in a traveling manner; Only the anchor's claws remain outside.
To prevent water from entering the deck through the hawse, the deck hawse is closed with a special hinged lid with a recess for the passage of the anchor chain.
To clean the anchor and chain from dirt and bottom soil with water when pulling out, a number of fittings are provided in the fairlead pipe, connected to the fire main.
On passenger and port ships, anchor fairleads are often made with niches - steel welded structures, which are recesses in the sides of the ship into which the anchor arms fit. An anchor drawn into such a hawse does not protrude beyond the plane of the side outer skin. These hawsees have a number of advantages, the main of which are the following: reducing the possibility of damage to ships during mooring operations, towing and moving in ice, as well as improving the fit of the paws to the outer skin by changing the slope of the inner surface of the fairlead.
Protruding hawse shown in Fig. 6.6 b, where its difference from a regular hawse is clearly visible. Protruding fairleads are used on ships with a bulbous bow, which eliminates the impact of the anchor on the bulb when it recoils.
Open hawse, which are a massive casting with a groove for the passage of the anchor chain and anchor spindle, are installed at the junction of the deck and the side. They are used on low-sided ships, where ordinary fairleads are undesirable, since water gets onto the deck through them during rough seas.
Anchor mechanisms serve to release the anchor and anchor chain when the vessel is anchored; locking the anchor chain when the vessel is anchored; unanchoring - pulling the vessel to the anchor, removing the chain and anchor and pulling the anchor into the hawse; performing mooring operations if there are no mechanisms specially provided for these purposes.
The following anchor mechanisms are used on seagoing vessels: windlass, half-windlass, anchor or anchor-mooring capstans and anchor-mooring winches. The main element of any anchor mechanism that works with a chain is a chain cam sprocket drum. The horizontal position of the sprocket axis is characteristic of windlass, the vertical position is characteristic of capstans. On some modern ships (for a number of reasons) it is not practical to use conventional windlasses or capstans. Therefore, anchor-mooring winches are installed on such vessels.
Windlass designed to simultaneously service the left and right side circuits. On large-tonnage vessels, half-lasps are used, offset to the sides. The windlass consists of an engine, a gearbox and chain sprockets and turrets (mooring drums for working with mooring lines) placed on the load shaft. The sprockets sit freely on the shaft and can rotate during engine operation only when they are connected to the load shaft with special cam couplings. Each sprocket is equipped with a pulley with a band brake. Windlasses ensure joint or separate operation of the left and right side sprockets. The use of friction clutches helps soften shock loads and ensure smooth engagement of sprockets. The recoil of the anchor at shallow depths is produced due to its own mass and the mass of the chain. The speed is regulated using the windlass band brake. At greater depths, the chain is etched using a windlass mechanism. The turrets sit rigidly on the load or intermediate shaft and always rotate when the engine is running. In the bow anchor device, both sprockets and mooring drums have one drive.
The capstan mechanism is usually divided into two parts, one of which, consisting of the sprocket and mooring drum, is located on deck, and the other, including the gearbox and engine, is located in a room below deck. The vertical axis of the sprocket allows unlimited variation in the horizontal plane of the direction of movement of the chain; along with a good appearance and little clutter on the upper deck, this is a significant advantage of the spire. Often the anchor and mooring mechanisms are combined in one anchor-mooring capstan.
Anchor-mooring winches. Currently in anchor device
|
Fig. 6.11. Anchor-mooring winch (half-lass with mooring drum). Scheme.
large-tonnage ships began to use anchor-mooring winches with hydraulic drive and remote control. These winches are composed of half-windlass and automatic mooring winches, which have one drive. Anchor-mooring winches can serve anchor devices with a chain caliber of up to 120 mm. They are characterized by high efficiency, lighter weight and safety in operation.
Anchor mechanisms can be steam, electric or hydraulic driven.
Stoppers designed for attaching anchor chains and holding the anchor in the fairlead in the stowed position. For this purpose, screw cam stoppers, stoppers with an embedded link (embedded stoppers) are used, and to press the anchor more tightly to the fairleads, chain stoppers are used.
The embedded stopper (Fig. 6.12) consists of two fixed jaws, allowing the chain to pass freely between them along a recess corresponding to the shape of the lower part of the vertically oriented link. On one of the cheeks, a slot is fixed in the slot, which freely fits into the cutout of the opposite cheek. The inclination of the cutout is such that the force created by the locked chain is completely absorbed by the pole. This stopper is recommended for chains larger than 72mm.
In a screw stopper, the base is a plate, in the middle part of which there is a groove for the passage of chain links. On small vessels, the horizontally oriented link is pressed against the base plate by two cheeks. The cheekpieces are hinged and driven by a screw with opposing trapezoidal threads. In the open position, the cheeks allow the chain to slide freely along the base groove. To prevent the chain from damaging the screw when moving, the stopper has a limiting arc. The chain is locked as a result of frictional forces when the chain link is pressed against the stopper plate by the cheeks. On large ships (with a large chain gauge), this method cannot provide the necessary force to lock the chain. Therefore, between the two is vertical. arranged links introduce cams located on the cheeks with a similar stopper pattern.
|
|
|
Fig. 6.12. Design of anchor chain stoppers: A– mortgage, b-screw, V - chain.
1 – base plate; 2-mortgage fell; 3 – cheek; 4 – gutter; 5 – pin; 6 – arc; 7 – screw; 8 – cheek; 9 – handle; 10 – chain; 11 – lanyard; 12 – butt; 13 – verb-hack.
A chain stopper is a short chain stopper (smaller gauge) that passes through the anchor shackle and is secured at its two ends to the butts on the deck. With a lanyard included at one end. chains, pull the anchor into the hawse until the paws fit snugly against the outer skin. The verb-hook, included at the other end of the chain, serves to quickly release the stopper. The windlass (capstan) band brake is used as the main stopper when the vessel is anchored. This type of locking has a number of advantages, among which the most important is the possibility of the chain being etched due to the brake pulley slipping relative to the brake band during jerking.
Chain pipe (deck fairlead) serves to guide the anchor chain from the deck to the chain locker. The chain pipe has sockets in the upper and lower parts. Chain pipes are positioned vertically or slightly inclined so that the lower end is above the center of the chain box. When installing a windlass, the top bell of the chain pipe is secured to its foundation frame. When installing the spire, an angular rotary socket is used, which consists of a cast body and a cover hinged in its upper part. The lid closes the bell, protecting the chain box from water getting into it, and allows, if necessary, to hold a section of the anchor chain on the deck for inspection, for which there is a hole in it corresponding to the chain link.
The length of the chain pipe depends on the location of the chain box along the height of the vessel. The internal diameter of the pipe is taken equal to 7–8 chain gauges.
Chain boxes designed for placement and storage of anchor chains. When selecting anchors, the chain of each anchor anchor is placed in the designated compartment of the chain box.
The dimensions of the chain box must ensure self-laying of the anchor chain when retrieving the anchor without manually pulling it apart. This requirement is met by cylindrical compartments of a chain box with a diameter equal to 30–35 chain gauges (in any case, the box should be relatively narrow). The height of the chain box should be such that the fully laid chain does not reach the top of the box by 1–1.5 m. At the bottom of the chain box, under the center of the chain pipe, there is a powerful semi-oval eye, through which the anchor chain, changing direction, is brought to the main end fastening. The chain box is self-draining.
Attaching and releasing the anchor chain. At the top of the chain box there is a special device for fastening and emergency release of the main end of the anchor chain. The need for a quick release may arise in the event of a fire on a neighboring ship, a sudden change in weather conditions, and in other cases when the ship must quickly leave the anchorage.
Until recently, the attachment of the root stop to the body was carried out by a chewing tack - containing a verb-tack. The chain was released only from the chain box.
Currently, for the release of the anchor chain, instead of the verb-hook, which is unsafe when the chain is released, they began to use folding hooks with a remote drive. The principle of operation of the hinged anchor hook is the same as the verb-hook, with the only difference being that the hinged hook stopper is released using a remote roller or other drive. The control of this drive is located on the deck directly next to the anchor mechanism.
