During the period of operation, for a number of reasons, ships can receive damage to the hulls in the underwater part. Most often this occurs due to impacts of ships on the ground, port facilities and various underwater objects, as well as collisions of ships. Damage is also possible in the underwater parts of ships and floating facilities as a result of overvoltage of the hull during heavy rolling or when sailing in ice. 116
Damage to the hull can be of three types: holes, cracks and loose seams; damage to the hull also includes loose rivets (riveted on older ships).
Holes in the hull can have a wide variety of configurations and areas from a few square centimeters to tens of square meters. Holes are characterized by the presence of torn and bent edges, as well as dents around them, which makes them difficult to seal and requires the use of various plasters.
Cracks and open joints can also be of various sizes in size, but in most cases they are small in width, which makes them easier to seal.
Inspection of damage to the hull. If the location of the damage is unknown, divers examine the hull from the end of the keel or the ladder. A detailed examination of the place of damage and removal of dimensions, as well as its termination, should be carried out from a working arbor. When examining, it should be borne in mind that when water enters the hole, there is a danger of the diver being pulled or sucked to the hole. Therefore, the diver must inspect and inspect the hole from the side, taking a position that prevents it from being pulled or pulled to the hole.
When examining ratchets and split joints, the diver determines their length and direction, as well as their width, so that later on the correct choice of wedges for sealing them. Inspection of holes in flat areas of the hull consists in removing their dimensions and inspecting the edges in order to establish the possibility of placing a plaster and the need to cut torn and bent parts; the dimensions of the holes are removed using a diving ruler or some kind of bar on which the diver makes notches.
If the hole is located on the chine of the ship in the area of the stem or sternpost and for its sealing it is necessary to put a figured plaster, the diver, using templates, removes the hull contours around the hole. The templates are also removed for placing patches on holes surrounded by dents. The most convenient templates are made of wood in the form of boxes or squares (Fig. 75); The boxy template is a quadrangular frame made according to the removed dimensions of the hole with the calculation of its overlap on all sides by 10-15 cm. reiki. The prepared template at the keel ends is brought to the hole, and the diver installs it in the same way as a plaster will be installed. After installing the template, the diver brings the slats one by one close to the hull of the vessel and fixes them with nails.
To remove the shape of the plasters in the areas of the stern and stem, square templates are used, which are made from two boards or bars with slats stuffed on them. Fitting the slats to
barely installing the square template on the keel ends is done in the same way as for the box template. With a significant change in the curvature of the body, two square templates are fastened at a distance equal to the width of the future patch.
Sealing cracks, loose seams and small holes. To seal minor damages of the ship's hull, wooden blunt and pointed plugs and wedges are used, their dimensions are set according to the results of the survey so that they, when driven in, enter at least 2/3 of their length into the sealed damage.
Rice. 75. Templates for removing body contours:
a - boxed template; b - template-square
Small plugs and wedges are fed to the diver at the hemp end with ballast, into which they are stuck between the strands; large - pre-ballast. The diver inserts a plug into the hole and hammers it in with a sledgehammer. If the cork does not hold tight enough or has entered the hole less than 2/3 of its length, the diver should bring it to the surface for additional processing. Also, the diver hammers one to another wedges into cracks and open seams. It is recommended to pre-wrap the wedges with a thin layer of resin tow.
After hammering in a wedge or plug, the diver cuts or unties the end and releases the ballast. If necessary, plugs and wedges are knocked out with resin tow and the leaks are coated with fat or special putty. Strongly protruding wedges and plugs can be sawed off to protect against falling out while the vessel is moving, which is best done 2-3 hours after setting, when the wood swells.
Application of semi-rigid plasters. Semi-rigid plasters are put on holes in most cases as a temporary measure of their sealing by the forces of the crews of ships without the participation of divers. Semi-rigid plasters are of different designs, more often than others the so-called mattress patch is used. It consists of soft tea
STY - two spacers Between themselves layers of canvas with a layer of tar tow - up to 200 mm thick. Boards with a thickness of 50-75 mm are attached to the soft part at intervals equal to the thickness of the boards, which is necessary for bending the plaster along the contours of the body. To fasten the boards, a layer of canvas is applied and nailed to them, which is then sewn to the soft part. On top of the boards, two pieces of steel cable with lights are applied and fastened with brackets, to which the heel ends are attached.
A patch-mattress, as well as other types of soft patches, is brought to the hole from the deck at the ends of the keels. The diver's job when placing a semi-rigid patch is to ensure that it is correctly positioned and adhered to the hull and that the ends are properly tightened. After installing the plaster and securing the paddle ends, the diver removes the ballast from the plaster.
Staging of hard plasters. Hard plasters can be made of wood or metal; in the practice of rescue operations, wood is more often used, since the manufacture of metal is more difficult and time-consuming.
Wooden plaster - has a rectangular shape and is made of boards according to the size of the hole, so that the plaster covers the entire hole. Depending on the size and depth of setting, the plaster is made from two or three layers of boards or bars, the thickness of the plaster is selected from the table. 6.
Table 6
|
Plaster thickness, mm, at a setting depth |
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|
plaster, m |
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0.3X0.3 0.5X0.5 1.0X1.0 2.0X2.0 2.5X2.5 3.0X3.0 4.0X4.0 5.0X5.0
A two-layer plaster is made from boards of the desired thickness cut in advance to the size of the hole. The first layer of boards is laid out of the blue, bars are applied from them and pierced with nails, the knocked down shield is turned over. A piece of canvas is placed on the shield, which should be about 200 mm larger than the shield on each side. The canvas is painted over with red lead over the area of contact with the shield and covered with a second layer of boards, nailing them along the perimeter to fasten with the first layer; the nails must be long enough to pass through both layers and can be folded back.
Around the perimeter of the finished board, lay the resinous tow so that a dense roller 70-130 mm wide and 30-40 mm high is obtained. The walnk is wrapped with the edges of the canvas protruding from the shield and nailed in such a way that a soft board forms along the edges of the plaster. Holes for the hook bolts are drilled in the finished plaster, the brackets are nailed to it for fastening the ends and ballasted.
A rigid plaster is installed on holes that do not have outward curved edges or dents along the edges. Outward curved edges
holes and protruding parts of the set are cut off by divers using electrooxygen or benzo-oxygen cutting. Fastening the plaster is the most critical operation to seal the hole. Tight application of the patch can be accomplished with hook and drop head bolts as well as with drop ends and guy wires.
To attach the plaster, the hook bolts are inserted into the plaster in advance along the perimeter of the hole. The number of bolts depends on the size of the patch and the conditions for its placement, but not less than one bolt with a diameter of 20 mm for every 0.5 m2 of the patch area.
The ballasted plaster is fed at the ends to the diver, he directs the plaster over the hole and inserts bolts into it. After the bolts are engaged, the diver, alternately rotating the wing nuts, achieves a firm pressing of the plaster to the body (Fig. 76).
If it is not possible to hook the bolt hooks onto the edges of the holes, you need to install pipe or profile steel sections from the inside of the body, for which you hook the bolt hooks. In difficult cases, the fastening of the plaster with hook bolts is carried out simultaneously by two divers, one of whom works from the inside of the hull.
A bolt with a folding head at its end does not have a hook, but a folding bracket - a head 450-500 mm long, which, when the bolt is inserted into the hole, is located along it, and then unfolds perpendicularly to hold it by the edges of the hole. This limits the use of flip-head bolts for placing small patches up to 0.5 m2, except in cases where the hole with a large length has a width less than the length of the flip-off head of the bolt.
The process of placing a patch on one or more bolts
Rice. 76. Setting gesture- "
of whom the plaster: 1 - the hull of the vessel; 2 - plaster; 3 - hook bolts; 4 - wing nut; 5 - soft board (valnk)
with hinged heads similar to hook bolt setting.
Fastening of the plaster on the keel ends and braces inserted through the hole into the ship's hull is carried out with the help of sheets that tighten the keel ends and braces after the plaster is installed in place.
Regardless of how the patch is attached, the diver should carefully inspect it around the perimeter in order to establish a tight fit to the hull. If leaks are found, the diver should tap the plaster with tow using a wooden wedge. Later, when pumping out water from the flooded compartment of the ship, the diver observes the plaster, identifies leaks in the water flow and eliminates them.
Installation of box plasters. Box patches are a type of hard patches and come in rectangular and curly shapes. Rectangular ones are installed on straight sections of the hull, when for some reason it is impossible to cut the protruding edges of the holes, and curly ones - on the uneven contours of the ship's hull, as well as in the presence of dents and bulges along the edges of the holes.
The rectangular box-shaped plaster - the plaster-box - is made according to the removed dimensions of the holes, and the figured one - according to the templates taken during the examination of the damage to the ship's hull.
The box-shaped patch has a bottom and side walls, which are the same in height for a rectangular patch, and with curved contours in a figured one, according to the removed template. To place a figured patch in places with a large curvature of the sheathing, the patch is made with a bottom, consisting of two parts, which are fastened at an angle of 90 ° to each other (Fig. 77).
The thickness of the bottom of the box patch is selected depending on its size and the depth of placement, as well as a simple rigid patch, according to table. 6. The thickness of the side walls should not be less than the thickness of the bottom, but they are usually made large for the convenience of stuffing the soft roll.
The tightness of the bottom of the box patch and its walls is achieved by laying a red-dyed canvas between the layers of boards or by subsequent caulking with tow.
Rice. 77. Box-shaped shaped plaster:
1 - bottom of the plaster; 2 - metal tires; 3 - pillow (roller); 4 - shackle; 5 - walls; 6 - metal sheathing
To give the box plaster the necessary rigidity, especially with large sizes and high wall heights, metal tires are used.
For the installation of the box patch, the same means can be used as for the installation of conventional rigid patches, however, due to the distance of their bottoms from the skin at a great distance, it can be difficult to use hook bolts and bolts with hinged heads. Therefore, box-type plasters, especially curly ones, are more often installed using podkilny ends and braces.
A wrecked ship often suffers from damage to the outer hull through which water enters the ship and causes it to sink. To give the ship positive buoyancy, the damage to the hull must be repaired and water must be pumped out of the ship.When carrying out a ship lifting operation, the holes are closed temporarily, only so that the ship can be brought to the repair point, where the appropriate repair is given to it.
Sealing with external plaster
In river practice, soft plasters are usually used, made of canvas in one or two layers. The plasters are made in square dimensions 1.5 X 1.5 m, 4.5 X 4.5 m and 6 X 6 m. Along the edges, the canvas is sheathed around a lyctrope, from which loops with thimbles are made at the corners of the plaster. The ends of a hemp rope with a circumference of about 75 mm are fixed to the thimbles, using which the plaster is put into place and fixed to the vessel.Putting tow between two layers of canvas in the plaster cannot be considered rational, as it causes the plaster to decay quickly and fail.
To close the hole in the ship's hull, the plaster is introduced from the outer side of the hull and, if possible, is pressed against it by the ends of the flap. If, at the same time, you start pumping out water from the damaged compartment, then the pressure of the water will press the plaster against the hole and stop the flow of water into it.
The patch is installed in the following order. On both sides of the damaged area of the hull, the keel ends are brought in, by means of which the ends of the cables attached to the two adjacent corners of the plaster are pulled under the ship. Selecting these ends from the opposite side, pull the plaster so that the middle of it falls against the hole. Then the ends are pulled back and fixed to the sides of the vessel.
The disadvantage of these soft patches is that if the hole has sharp outwardly projecting edges, the patch can easily break. Equally, a soft plaster cannot stop the flow of water through the hole if the size of the latter is very large, since in this case the plaster will be squeezed into the vessel by water pressure.
In such cases, instead of a soft plaster, the so-called Swedish plasters are used, made of two or three layers of boards 50-75 mm thick, between which canvas and tar tow are laid. In the places where the Swedish plaster adheres to the body, wooden strips are sewn, upholstered with soft pillows for a tighter fit. To neutralize the positive buoyancy, metal weights (usually pieces of old chains) are suspended from the plaster.
To close especially large holes, the wooden plaster is shaped like a box. Such a patch is called a caisson. The caisson is fastened with the keel ends. To maintain strength, spacer bars are placed inside the box.
Internal plasters
The plaster used to seal the damage to the hull from the inside of the vessel is made as follows. A layer of tar tow is applied to a piece of canvas or an ordinary bag, which exceeds the area of the hole by about three to four times; tow from above is smeared with a hand with an even layer of grease, on top of which a layer of tow is again placed, and again canvas on top. Such a patch is easily tied up and down with a thin string or cable. The total thickness of the plaster is about 5-8 cm. The plaster is placed on the damaged area of the case, and on top of it are placed scraps of boards 50-75 mm thick. It is better to hammer these trimmings tightly between any parts of the hull set, for example, between frames, floras or stringers. Due to the fact that the water pressure tends to push the plaster away from the hole, logs or thick boards are placed on top of the boards, which are firmly bursting into beams, carlings or other reliable hull connection.If the leakage through the hole is not so strong that it could prevent the installation of the internal patch, then the sealing in the described way quite reliably withstands a rather long passage of the vessel.
Sealing with an external swab
Tampons are used to temporarily plug small holes, and especially in those cases when the application of plasters is impossible. A tampon is made in the same way as an internal plaster, and is brought to the hole by a diver from the outside of the vessel. When the tampon is injected, water must be pumped out at the same time, since only under this condition will the tampon be pulled to the hole, partially penetrate into the hull and stop water from entering the vessel.If the diver cannot approach the hole, maybe, then the tampon is tied to a fairly long stick on a string about 30-40 cm long, counting from the end of the stick to the tampon. With this stick, the diver drives a tampon under the body in the area of the hole until a stream of water pulls it up and clogs the hole. In this case, of course, the water from the vessel must be pumped out. Sometimes it is possible to put a tampon in place by driving it on a long stick, from a boat or even from the emergency ship itself,
Having achieved the termination of water access to the vessel, they completely pump out and seal the hole from the inside, after which the tampons fall off themselves.
Wood embellishments
Small cracks and holes in the outer hull, loose joints and grooves in the skin can be temporarily sealed by a diver using wooden wedges driven in from the outside of the vessel. Wedges are made of dry wood in order to increase the density of the embedment after swelling in water.Wooden wedges are temporary and must be replaced immediately after the ship arrives at the repair point.
It is sometimes possible to stop a slight flow through small cracks along the parted grooves and joints of the outer skin by letting sawdust, bran or debris from ant heaps outside the ship against the leak: small pieces of wood or bran are clogged and cracks, swell and the flow stops.
It goes without saying that such a method of stopping a leak is temporary, suitable only for the duration of a short passage of the vessel to a repair point.
Sealing Yemeni
Cementing is not only reliable in dry conditions! hold, but also under water. In the latter case, for a reliable seal, the work on laying the cement must be done with great care. When repairing damage, fast-setting cement grades should be used to avoid unwanted erosion and leaching. Before laying the cement, the damaged area must be thoroughly, to a shine, cleaned of paint and rust and washed with green soap. It is not recommended to touch the gland prepared in this way with your hands, so as not to apply a layer of fatty substances and not cause the cement to lag. To prevent the cement from creeping, it is necessary to arrange plank formwork around the entire damage.It is much more difficult to perform cementing in the event that water continues to flow through the damage, which easily punches itself a channel in the freshly applied layer of cement. In such cases, it is first necessary to drain this water through a piece of pipe or a specially knocked down wooden gutter. Having installed such a drain, the entire area around it is cemented. After the cement has set, the created water runoff is tight (clogged with a plug,
In case of large damages that have caused a weakening of the body, it is necessary to lay a frame made of iron rods, wire or pieces of iron inside the cement to increase the strength of the seal.
For sealing holes, cement is taken in a mixture with sand, in a proportion from 1: 1 to 1: 4, depending on the required strength and the speed of its setting. The less sand, the faster the setting is usually.
To reduce the leaching of concrete by water during its setting and to accelerate this process, concrete should be mixed in warm water to which liquid glass has been added. After placing the concrete in the formwork, it must be well compacted, which ensures greater water resistance during hardening.
It is not necessary to seal the holes with a solution of pure cement, as is sometimes observed in practice.
When choosing a concrete composition, you can use the following table:
Clay filling
Clay filling is not durable and is used only as a temporary measure to stop the leak until the damage is repaired more reliably. This method is completely inapplicable if any significant amount of water continues to flow into the hole.When plugged from the outside with a plaster; water intake, work is done as follows. Around the damage, the most dense formwork is arranged from the boards, and the individual boards should be fitted as accurately as possible to the shape of those parts of the hull to which they adjoin. Clay is laid in layers and tightly rammed into the formwork. The thicker the clay layer, the more reliable the embedding. It is useful to lay some layers of clay mixed with fine shavings, straw or sawdust, which delay the washing out of the clay by seeping water. In addition, after removing the outer plaster, it is good to bring sawdust to the place of damage, which is carried away by jets of water into the hole, fill individual cracks in the seal, swell and thereby: stop or greatly reduce the flow of water into the vessel.
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Currently, small vessels with hulls made of fiberglass are becoming more and more widespread, so it is advisable to summarize some experience in repairing such vessels by amateurs.
During the operation of ships, damage to the hulls when they hit invisible underwater obstacles (drifts, stones, piles, etc.) pose a great danger. When the plastic housing hits an obstacle, the following main types of damage are possible:
1) holes in the skin;
2) separation of the set from the casing;
3) deep (more than half the thickness of the plating) scratches.
Let's consider the repair of these three main types of damage to the plastic case separately.
Holes in the skin
Holes in the hull usually occur when the hull strikes at high speed against a sufficiently sharp obstacle close to the surface of the water. The damaged vessel must be lifted out of the water and installed on the shore (on keel blocks, etc.) so that it is convenient to work in the area of the hole. Then a thorough examination of the damage is carried out and the boundaries of the hole are established (holes can be drilled at its ends).The entire damaged section of the skin is cut out of the body along with the kit. The cutout should be rectangular, but with the obligatory rounding of the corners (Fig. 1). The set, which has fallen into the damaged area, must be cut off at a distance of 100-150 mm outward from the contour of the cutout in the casing, cut down and also removed. Cutting fiberglass of small thicknesses (2-5 mm) can be done manually - with a hacksaw with a hacksaw blade made of R-9 steel.
To be able to seal the cutout, it is necessary to make a bevel of the edges with a width of at least 10-12 sheathing thicknesses along the entire perimeter of the cutout (Fig. 2). It is best to use a pneumatic machine with an elastic lacing circle for this purpose (Fig. 3), but with a certain skill, the bevel of the edges can be done with a sharp knife and a hammer (Fig. 4) or even a file.
The surface of the edges on both sides of the cutout must be dried (for example, with a 300-500 W lamp with a tinplate reflector or an electroreflective furnace of the "Neva" type) and must be degreased with acetone or gasoline with an exposure time of 20 minutes before filling the hole. to evaporate the degreasing agent. The hole must be sealed with plywood, which must follow the contour of the body at the cutout (Fig. 5). For this purpose, you can use plywood with a thickness of 3-4 mm, bending it according to special patterns, taken in place from the other side (Fig. 6), and fixing it to the same patterns.
A separating layer is applied to the plywood, after which the hole is molded from the inside with fiberglass impregnated with a binder (inner cover of the hole). The area of each layer of fabric gradually increases, and the bevel of the edges is completely filled. It is necessary to lay the layers of fiberglass until the surface of the inner lining and the skin is leveled (fig. 7).
After polymerization of the inner lining, the plywood embedding is removed, and the surface of the lining that was in contact with the plywood is cleaned to remove the release layer and also degreased. Then the outer cover of the hole is formed, but not along the plywood embedding, but directly along the inner cover. The section through the sealed hole is shown in Fig. eight.
To polymerize the linings, it is necessary to warm up with a lamp with a reflector or an electroreflective oven. When working in rainy weather, an awning should be made over the repair site to prevent water from entering directly into the forming area.
Before installing a new set instead of the removed one, thoroughly clean and degrease the inner surface of the casing.
Then glued in (on BF glue or K-153 compound), carefully adjusted in place, the pieces of the new designer ("strength filler", "core"), most often wood. The docking of the decorator is made at the end or with a bevel "on the mustache". After that, the new areas of the decorator are molded to the skin and ends of the old set with layers of fiberglass impregnated with a binder. The overlap of the joints of the set should overlap the ends of the old set by 120-150 mm (Fig. 9).
Both sides of the hole filling are cleaned for painting and painted.
Separation of the set from the casing
The separation of the set from the skin occurs when the hull strikes a large underwater obstacle (stone, pile, etc.). Sometimes the tearing off of the molded set (especially in the bow) occurs during a long course of the vessel in the mode of planing on waves, when strong impacts of the hull against the water are observed.The part of the set that has lagged behind the casing must be cut out and removed, and the casing must be thoroughly cleaned and degreased before installing a new set. The installation and shaping of the new decorator is carried out in the same way as when installing the kit when sealing a hole. After polymerization of the moldings, they must be cleaned and painted.
Sealing deep scratches
Deep scratches occur when the case touches sharp objects (for example, sharp stones).Deep scratches should be repaired as soon as they are found, since in places of such damage, the strength of the skin is significantly reduced. Deep scratches in the plastic housing are the centers from which the sheathing begins to delaminate.
Deep scratches are repaired as follows. The skin around the scratch is cleaned as described above in such a way that an oval-shaped depression is obtained for the entire depth of the scratch, with a bevel around the perimeter (Fig. 10). This recess is then molded in the usual way with layers of resin-impregnated glass cloth until it is aligned with the skin surface (fig. 11). After cleaning, the molded surface must be painted over.
The main types of damage described above occur most often when the body hits an obstacle. But damage to the skin can be caused by other reasons as well. For example, during long-term operation of a vessel in shallow water or frequent approaches to the shore in shallow places, from frequent contacts with the bottom (especially when it is rocky or sandy), the bottom plating of the hull is abraded, primarily in the bow. Therefore, it is recommended to reinforce the cladding in this area with additional layers of fiberglass even during the construction of the hull (especially in the area of the keel in the bow). With prolonged use, the abraded surface must be refurbished. To do this, it is necessary to dry the worn-out area of the cladding, clean it and degrease it, and then mold the required number of layers of fiberglass onto it.
Vibration from the outboard motor (especially two motors) can damage the transom. There were cases when, during the operation of a boat with two outboard motors "Moskva", cracks appeared in the corners of the sub-engine cutout in the transom, which could lead to the complete destruction of the transom (Fig. 12).
Repair of this unit must be done as follows. The ends of the cracks should be drilled out to prevent further propagation. Then the area of cracks must be cleaned on both sides and a wooden knit with a rounding should be inserted into each corner of the cutout. The thickness of the knee should be equal to the thickness of the transom (fig. 13).
The knit is glued to the transom with epoxy compound or BF glue. Then chopped resin-based fiberglass is hammered into the crack, and the entire crack area, together with the knit, is molded with resin-impregnated fiberglass (Fig. 14). The thickness of the molding should be equal to half the thickness of the transom. The transom repaired in this way does not show any signs of new destruction during further operation.
During the operation of the vessel, damage such as lifting eyelets, ducks, bollards from the deck is also possible. In this case, it is necessary to cut out the attachment point of the torn part to the deck, then round off the corners of the cutout and make a bevel of the edge (Fig. 15). Then plywood is installed from below and the cutout is molded (Fig. 16), as discussed above.
Since the deck at the place where the hole is sealed will be somewhat weakened in comparison with the whole area, it is advisable to put the eye or bollard in a different place. If this is not possible and the part has to be put in its original place, then a reinforcing plate with a thickness equal to half the thickness of the deck must be placed to seal the hole in the deck (Fig. 17).
On small ships with stationary power plants, upon impact with the bottom, the seawater Kingston's molding sometimes breaks off, in connection with which water begins to flow into the engine compartment. To temporarily stop the leak, you can use wet rubber and a metal yoke 50-60 mm wide. The rubber should be laid around the kingston, overlapping the vertical flange of the molding square by 20-30 mm, and squeezed with a yoke (Fig. 18). The flow of water into the boat will either decrease sharply or stop.
Upon returning the vessel to the mooring place, it is necessary to lift it up on the wall or hang the stern over the boom or over the gentle bank (in case of minor damage) and repair the damaged attachment. Repair should be done as follows. Cut off the inner and outer kingston squares completely. Thoroughly clean the surface of the kingston, as well as the surface of the bottom (inside and outside) in the damaged area. Kingston is put in place and loosened. First, the kingston is molded from the inside. The first layer of an epoxy-impregnated molding square is placed on the kingston and the bottom and carefully smoothed so that there are no air bubbles under it. Then the remaining layers of the molding square are laid, impregnated with ordinary resin.
After polymerization of the inner molding square, it is necessary to check it for impermeability. The inner molding square is coated with soapy water, and from the outside, compressed air is supplied from a hose with a pressure of 3-3.5 kg / cm 2 (if there is no compressed air line or compressor, you can use a car cylinder).
If there is no air leak, the outer molding square is molded, after polymerization of which the repair can be considered complete. In case of detection of air passage along the edges of the pre-molding square, these places must be repaired again.
Only the main types of damage to fiberglass hulls are considered. Repairs to any other damage are the same as those listed above.
When repairing a ship's hull made of fiberglass, you can use any reinforcing materials - fiberglass, glass mat, fiberglass, etc., as well as any brand of resin. Temperature conditions for the polymerization of fiberglass (that is, the temperature is not lower than 18-20 ° C) can be created either by lighting lamps with a power of 300 or 500 W with reflectors made of tinplate, or by reflective furnaces of the "Neva" type.
Going on a long journey on a ship with a fiberglass hull, you need to take with you a small amount of resin (1-1.5 kg) with curing additives and fiberglass. Resin and cloth are needed to repair hull damage that can occur when sailing in various water systems. If it is not possible to take resins and fiberglass with you, you must have an epoxy compound, which can also be used to repair minor damage to the case.
The ships of the marine fleet, according to the Register Rules, are not supplied with rigid plasters. If necessary, in a shipboard environment, it is most simple and quick to make a hard plaster in the form of a single or multi-layer wooden board with soft pillows of tow or felt around the perimeter.
The location of the planks in the patch depends on the shape and size of the hole. It is advisable to produce a patch with an aspect ratio less than two in two layers, with a mutually perpendicular arrangement of the boards in layers.
To close narrow and long holes, it is more expedient to use one- or two-layer plasters with parallel arrangement of boards in layers. The boards should be located across the holes.
Hard plasters it is most advisable to use for closing holes located above or near the waterline, as well as in cases when it is possible to expose holes by inclining and trimming the vessel. This creates the most comfortable conditions for applying the plaster and makes it possible to do without the help of divers.
In case of narrow holes, the plaster is fastened using ordinary straight bolts passed through the plaster boards and metal strips placed from the inside of the vessel across the hole through its edges.
For wide holes, the patch is attached to the hole with hook bolts. taken from the inside - by the edges of the hole and also passed through the plaster. Additionally, in the center of the patch (along the axis of the hole), several butts or eyelets can be installed for attaching guy wires with lanyards from the inside of the vessel. 2.3. Sealing holes by concreting
Concreting is the most reliable way to repair damage to a ship's hull. With the help of concreting, it is possible not only to eliminate the watertightness of the case, but also to partially restore its local strength in the damaged area.
Concreting can be carried out both in drained and flooded compartments. The latter is a more difficult operation, it is less reliable. In this regard, underwater concreting is used only in cases where it is not possible to drain the compartment.
The constituent parts of the concrete solution are: binder (cement), aggregate (sand), fresh or sea water. When concreting damages in the above-water part of the hull, in addition to sand as an inert filler, gravel, crushed stone, etc., can be added in the presence of gravel (Table 2.2).
Table 2.2
Composition of concrete for sealing damage in the ship's hull (volumetric proportions)
|
Concrete type and composition |
Inert aggregates (gravel, crushed stone, etc.) |
Volume proportions |
Notes (edit) |
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|
Greasy concrete |
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|
For concreting in the underwater part of the hull. For concreting in the underwater and above water parts of the hull. For concreting in the above-water part of the hull |
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Skinny concrete |
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For the upper layers of concreting. |
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For preparing concrete mortar ordinary Portland cement, pozzolanic Portland cement, alumina (bauxite) cement, Baidalin cement and VVC cement of grades 400, 500, 600 * can be used (The cement grade shows the ultimate strength of concrete prepared from a 1: 3 solution, 28 days after hardening.).
Portland cement is the most widely used cement. However, in some cases, it is advisable to use other cements. So, for underwater concreting, it is better to use pozzolanic Portland cement, which is resistant in an aqueous environment.
For concreting at low temperatures, alumina cement is the best, since, firstly, the hardening of the concrete prepared from it is accompanied by an increase in temperature, and secondly, in the concrete there is a rapid increase in strength immediately after the mortar has set.
Such a quick-setting cement is VVTs (waterproof, quick-setting), from which concrete, after about 6 hours, acquires half of its strength. An even faster setting cement is Baidalin cement. However, the concrete prepared from it begins to crack in 2-3 months. This type of cement is advantageous for short-term concreting *.
The physical and mechanical properties of some types of concrete, prepared from cement grade 400 with a ratio of 1: 3 with filler, are given in table. 2.3.
Table 2.3
Information about concrete
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Name |
Setting time, h |
Mechanical strength (1x98066.6 Pa) |
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not later |
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one . Portland cement-400 2. Pozzolanic portland cement-400 3. Alumina cement-400 4. Baidalin cement |
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Note. In the numerator - when solidified in air, in the denominator - in water.
Acceleration of the concrete hardening process can be achieved by adding special hardening accelerators to it, which can be used as:
liquid glass, which is added to water during the preparation of concrete in an amount of 10-12% of its volume;
calcium chloride, which is introduced directly into the cement in an amount of 2-10% of its mass and is thoroughly mixed with it;
technical soda in an amount of 5-6% by weight of cement, which dissolves in water during the preparation of concrete;
technical hydrochloric acid added to water in the amount of 1.0 - 1.5% by weight of cement.
The specified hardening accelerators accelerate the setting process of concrete by about two times, however, at the same time, they also reduce its strength. The best of these accelerators are technical soda and technical hydrochloric acid.
For repairing minor damage, it is better to use fine sand as an aggregate. For large volumes of concreting, in addition to sand, gravel and crushed stone are used as fillers. In their absence, you can use fine brick and, in extreme cases, slag, but not more than 25-30% of the total filler volume.
All fillers used for the preparation of concrete should, if possible, be washed in clean water and not have fatty impurities that violate the strength of the concrete. For the preparation of concrete, you can use both fresh and sea water. The use of seawater reduces the strength of the concrete by about 10%. The water should be clean, not contaminated with oil, oils and fats.
The concrete solution is prepared on a clean deck or in a special box, as close as possible to the place of its use, and includes the following sequence of operations:
filler is poured in an even layer on the deck or across the entire area of the box;
a uniform layer of cement is poured over the filler layer;
a second layer of aggregate is poured over the cement layer;
all three layers are thoroughly mixed, and then raked to the sides, forming a thicket;
fresh or sea water is poured into the bowl in an amount equal to about half or slightly less than the volume of cement; almost in a mixture of cement and sand, water is added in small portions as they are mixed;
the resulting concrete solution is mixed with shovels until a completely homogeneous mass is obtained and the solution takes the form of a thick dough.
In the place designated for concreting, a formwork is installed, the so-called cement box with two open sides, which with one open side adjoins along the perimeter to the place of damage, through the other side it is filled with concrete.
To ensure a tight fit, spacers made of felt or resin tow can be used. If the damage is small (cracks, etc.), the box can be directly filled with concrete.
With a significant size of the hole, it must first be closed with reinforcement made of steel tubes or rods arranged in the form of a mesh with cells from 10 to 25 cm and tied with wire at the crosshairs. The armature is attached to the body, and after that the box is filled with concrete (fig. 2.12).
For a tight connection of concrete with the body, it is necessary that at the place of concreting it was thoroughly cleaned from rust and dirt and washed with soap and caustic soda. The concrete must be fed to the place of laying continuously, so that each subsequent layer of mortar is applied to the not yet hardened layer. If, for some reason, a break occurs in the supply of concrete and the mortar in the cement box hardens, then before further supply of fresh concrete, a metal mesh or steel sheet or strips must be placed on top of the hardened layer.
Rice. 2.12. Schematic diagram of the concreting of the hole:
1 - concrete; 2 - a cement box made of sandbags; 3 - sand; 4 - sandbags, 5 - reinforcing steel mesh; 6 - lattice
For the protection of fresh concrete from erosion by water, which can seep through the hole, special branch pipes are installed in the cement box. The section of the branch pipe must ensure the flow of filtration water without creating a pressure.
The method of installing the tube depends on the nature and location of the hole (Fig. 2.13). However, in all cases, it must go from the bottom point of the hole, and its outer end (the surface of the drained water) must be below the concrete level.
After the concrete has hardened the tube is muffled with a plug. The fastening of a wooden shield or a hard wooden plaster with soft sides on the hole is carried out using hook bolts, for which special holes are drilled in the plaster (shield).
Rice. 2.13. Placement of the cement box on board the vessel:
1 - soft plaster; 2 - internal formwork; 3 - concrete; 4 - external formwork; 5 - spacers; b - spacers of the internal formwork; 7 - shield; 8 - branch pipe; 9 - supports; 10 - persistent bars
Sealing damage to the ship's hull with concrete has significant advantages over other methods, as it is distinguished by reliability, durability and tightness. With the help of concreting, it is possible not only to eliminate the watertightness of the case, but also to partially restore the local strength in the area of the damaged case. Sealing of holes with concrete is carried out for more reliable sealing of the ship's hull after temporary sealing of the hole with a plaster, especially in hard-to-reach places (under the foundations of steam boilers, mechanisms, at the ends and on the cheekbones of the vessel). In addition, practice has shown that in most cases only concreting can restore the tightness of the flooded compartments of a ship sitting on stones or on hard ground.
The disadvantages of concreting damages are that it is a very complicated and time-consuming procedure. Concrete does not tolerate vibration well and has low tensile strength. Concreting must be done in a dry environment, as underwater concreting is much more difficult and less reliable.
Surface and underwater holes can be filled with concreting. The simplest is to seal holes located above the current waterline, in the event that it is not possible to weld these leaks using gas or electric welding. Such a seal is carried out if there are small holes in the casing, cracks, which are previously closed with plasters, plugs, wedges; caulk; the ship's hull in the damaged area is thoroughly cleaned; in hard-to-reach places it can be burned with a blowtorch; then the formwork is installed and poured with concrete.
Figure 9. Placement of the cement box on the hole. a - bottom; b - onboard; 1 - emphasis; 2 - formwork; 3 - drainage pipe; 4 - hard plaster; 5 - wedges for an emphasis; 6 - hole wedge.
Cement box installation
In general, the organization of the installation of a cement box on a hole located in the underwater part of the ship's hull is carried out as follows (Fig. 9):
· If it is possible to install a soft plaster on a hole on the outside of the hull, it is advisable to do this, excluding large leaks of water into the emergency compartment;
From the inside of the emergency compartment on the hole, it is necessary to install and unfasten a hard plaster 4 in the form of a wooden one with soft sides; if a plaster of the required size is not on board, it should be made;
· The board in the area of the hole is thoroughly cleaned;
• hammer together a wooden internal formwork (box) around the hole (around a hard plaster or plugs, yushnyev), consisting of four walls and a lid; it is recommended to press the formwork tightly against the emergency side; the cracks in the box are carefully sealed (digging through); if the situation permits, it is more expedient to use a metal box;
A hole is made in the lower part of the box and a drainage metal tube is installed with a slight slope 3 (tube diameter 3 must be selected in such a way that the water drains freely without pressure);
· Above the inner formwork, a second, outer box (formwork) of a larger size is installed, consisting of only four walls (without the top cover); the distance between the walls of the outer and inner boxes and the excess over the lid must be at least 250 mm;
· The length of the drainage tube is selected so that it goes beyond the outer box (formwork);
After fixing the formwork, the space between the walls of the boxes is filled with a previously prepared cement mortar;
· After the final hardening of the cement mortar, the hole in the drainage pipe is clogged with a wooden plug.
Preparation of cement mortar
The cement mortar (concrete) must be made near the place of work (if the size of the emergency compartment allows) on a special flooring with sides made of tightly knocked down boards.
Components of the cement slurry and their ratio:
1.fast-hardening cement (Portland cement, alumina cement, Baidalin cement or others) - 1 part;
2. filler (sand, gravel, broken brick, in extreme cases, slag) - 2 parts;
3. concrete hardening accelerator (liquid glass - 5-8% of the total composition of the mixture, caustic soda - 5-6%, calcium chloride - 8-10%, hydrochloric acid - 1-1.5%);
4. water (fresh or outboard, however, the preparation of concrete on sea water reduces its strength by 10%) - as required.
First, filler (sand) is poured onto the flooring, cement is poured on top, then the constituent parts of the cement are mixed, they work, as a rule, together, raking with shovels towards each other.
Pour water into the middle of the mixture in portions and mix thoroughly until a homogeneous mass is obtained, resembling a thick dough.
To reduce the hardening time of the cement slurry, accelerators are added as a percentage of the total composition of the mixture indicated above.
The prepared mortar is immediately filled in the space between the inner and outer formwork. The cement sets in about 8-12 hours, and finally hardens after 3 days.
When concreting significant holes in the solution, it is advisable to install reinforcement (wire-tied steel rods) welded to the ship's hull.
The different options for concreting damages are shown in Figures 2 - 7. The installation of a cement box (concreting) is a temporary measure. Therefore, when the ship is docked or upon arrival at the port, the damaged connections are replaced or the holes are welded. In the event that it is not possible to dock the ship, the concrete embedding on the ship's hull is scalded, i.e. enclosed in a steel box welded to the body. At the same time, if possible, then the crack itself or a seam in the ship's hull is welded from the outside or from the inside. The sheets that form the wall of the box around a concrete embedment or cement box are usually welded directly to the hull or kit of the ship. Then all the free space of the cement box is filled with a new solution and welded on top with overhead sheets.