This is a special project for me, because my first boat was built on it.
The quarter-ton project, offered to the attention of the readers of "KiYa", was developed in the hard currency of the Leningrad Shipbuilding Institute "Ocean" on the basis of the "ST-25" project. The new sailboat is designed to be built from available materials by amateur shipbuilders, mainly in sports teams. The main version of the sailboat is designed for successful participation in cruising races in sea and lake conditions. A sloop-type sailing armament with a flexible mast, advanced rigging and a large mainsail is provided. All halyardsGuy lines were led to the deckhouse, where halyard winches were installed (they are also used to control the spinnaker). The running ends of the backstays are carried to two winches in the aft part of the cockpit; a wiring option using a block system is also possible.Основные данные яхты «СТ-251»
(in brackets - data of the tourist option)
|LOA, m||7.78 (6.98)|
|Hull draft, m||0.38|
|Maximum draft, m||1.50(1.10)|
|Fin weight, kg||600|
|Sail area (mainsail + staysail), m2||37 (34)|
Yacht control is concentrated in the cockpit, which has increased dimensions (width in the middle part is 1.3 m). The shape of the cockpit allows the helmsman and clews to move closer to the side to tilt the sailboat; creates improved visibility and the ability to easily change posture. The epaulette of the boom sheet is placed on the deck in the center of the cockpit. To adjust the staysails, short longitudinal shoulder straps are installed along the cabin coamings. There are also rails for blocks of sheets of narrow staysails - they are fixed on the deck aft of the shrouds.
You can get inside the sailboat through a sliding access hatch. Its location and dimensions (650X650 mm clear) allow you to put on deck and remove the sails, so there is no forluk on the sailboat, it is replaced by a small porthole and a ventilation deflector on the wheelhouse deck. As the upper step of the ladder, a part of the retractable chart table is used, which is stored under the bottom of the cockpit. To the right and left of the cockpit in the "coffins" there are two berths, convenient for resting on the go of the sailboat.
In the central part of the cabin along the sides there are sofas 1.95 m long, under which there are lockers for shoes. The outboard motor is stored under the cockpit. Instead, a light (40-60 kg) stationary engine can be installed. Above the sofas there are shelves for small things, in the bow there are two wardrobes. The galley, extended to the DP, is equipped with a two-burner gas stove in a gimbals suspension and a drawer for dishes. The plate is closed by a movable cover which forms a cutting table. There is also a folding dining table 650X65 in size0 mm, leaning back from the back of the galley. The sailboat is ventilated through the deck deflector, access hatch and ventilation hatches in the aft cockpit.
The space ahead of the mast is reserved for storing sails, waterproof clothing, anchors, spare lines, etc. The dimensions of this room allow, if necessary, to place two more people in it for the night.
Housing construction features
The hull of the sailboat is recommended to be built with a longitudinal framing system and diagonal laminated planking of plywood strips. The rigidity and strength of the plating is provided by frequently supplied stringers (9 on each side), which are attached to the frame frames and bulkheads.
The construction of this sailboat can be recommended to a team that includes at least one or two people with experience in assembling wooden ship hulls and locking skills. The books of G. V. Efremov “Assembler of Wooden Vessels” will help as a guide. P., "Shipbuilding", 1968 and D. A. Kurbatov "15 projects of ships for amateur construction", L., "Shipbuilding", 1985 (III edition).
It is highly desirable to arm yourself with an electrified tool: a circular saw, a planer, a drill and a grinding machine. It is necessary to assemble the case in a room protected from rain and sunlight, and in winter it must be heated. Most hull designs are made with glue, so the room must be well ventilated. Simultaneously with the procurement of all the necessary materials, you can begin to draw on a plywood sheet the contours of theoretical frames in full size. Frames must be deductedsew completely on both sides so that according to the marking it is possible to assemble absolutely symmetrical patterns, which, when placed on the slipway, will set the shape of the hull. The bypass according to the pattern is obtained by postponing from the bypass of the theoretical frame inside the hull the thickness of the outer skin and longitudinal stringers (25 mm). Sheathing can be done according to one of the following options :
- a) 2 layers of plywood BP-A npi BS-1 4 mm thick;
- b) 3 layers of plywood, 3 mm each;
- c) 4 layers of plywood, 2.5 mm each;
- d) 3 layers of pine or cedar boards 4 mm thick.
Thus, the total thickness of the skin will be 9-14 mm, and the outline of the pattern should be 35-40 mm from the theoretical line of the frame to the DP. Patterns are made from well-dried boards 20-25 mm thick, taking care of the reliable connection of all parts. After finishing the curved edges, they are put on a slipway - a rigid and durable frame of two parallel bars with a section of about 150X75 mm with a horizontal upper edge adjusted to the level. It is more convenient to assemble the hull in the keel up position. Simultaneously with the patterns, they installed on the slipwaythey lay and temporarily fasten the transom harness and the pre-glued stem. Patterns must be securely fastened, as they are used for pasting from thin boards - lamellas - keel beams. The keel beam package is attached to the patterns with clamps so that after the glue has hardened, the beam can be removed and processed into a clean size. In the nose, starting with sp. No. 3. The keel can be narrowed to the width of the stem. Next, proceed to the final installation and fastening to the patterns of the keel beam, stringers and fenders. For this purpose, theflax shorty 30X30X3 and screws. The distance between the stringers on the midships: along the bottom - 150-170, in the cheekbone area - 160-180, along the sides - up to 200 mm. The ends of the stringers and fenders are cut into the stem and transom trim and fastened with glue. Stringers should be laid without twisting the rails, as smoothly as possible. It is recommended to place the stringer on the bottom along the buttock pines, along the cheekbone - along the fish, along the sides - along the waterlines. When doing this work, it is necessary to control the smoothness of the contours, then remove the bevels from the stringers in those places where it is needed.Applying a flexible rail 1.5-2 m long to the stringers in different directions, make sure that it fits snugly along all edges. In area 6 of the theoretical frame, water channels are made on each stringer for the free flow of condensate from the sides into the bilge.
Having determined how the outer skin will be made, prepare the required number of strips of plywood or thin cedar boards. The width of the strips should be 100-150 mm, and the length is sufficient to cover the side from the boil to the fender. The set is covered with the first lining of the skin, adjusting the edges of adjacent strips so that the gap between them does not exceed 0.5-1 mm. The strips are laid on the set symmetrically from both sides, approximately at 45° to the DP, moving from the midsection to the extremities. Each strip after fitting the edges is temporarily fixedto the set. When the entire surface of the case is covered, the strips are numbered, removed from the set and folded with a foot.
Then proceed to the final formation of the first layer of skin. Each strip is attached to the stringers, keel and fenders with wood flour epoxy glue. The strips are attached to the set with nails and "flies" (nail pitch 40-50 mm) or with the help of wire clips hammered with a special gun. The pressing of the strips should be carried out as symmetrically as possible from both sides. On the stem, fenders and transom, as well as at the installation site of the deadwood lining, the skin is released over the edge by 15-20 mm.
After the glue has cured, the “flies” are removed, the skin is sanded, cracks and dents are puttied with glue with wood flour. The entire surface of the first layer is covered with glue, then the laying of subsequent layers of strips is started.
The finished skin is attached to the stem, keel beam and transom strapping with screws, to stringers and fenders - with screws or copper rivet nails with a pitch of 100-150 mm. Trim the allowances on the sides. install the keel pad-deadwood and water cutter.
Now you can detach the patterns from the slipway and turn over the body. By this time, frame frames and bulkheads should be assembled into knots, as shown in the drawings. The patterns are removed from the hull one by one and the frames and bulkheads are installed in their places.
They are attached to the skin through stringers with screws or copper rivet nails. It is allowed to use threaded fasteners - screws and bolts with a size of at least M6.
The hull is glued on the outside with 3-4 layers of fiberglass (only for the “a” cladding option, in other cases it is not necessary). Pasting should be done very carefully, because if water gets between the wood and fiberglass, the plywood begins to rot quickly, which is quite difficult to detect.
The remaining patterns can be used to build the next building. If it is planned to build only one hull, then pre-assembled frame frames and bulkheads can be used as templates, which will immediately go into the design of the sailboat.
The hull made in this way is 15–20% lighter than the hull of traditional design with sheathing made of gelled lath, has high rigidity, and is well ventilated. In addition, it is cheaper and less labor-intensive to build, requires fewer materials and processing operations, and does not require high qualifications of people performing the assembly.
The ballast fin of the sailboat is welded from steel sheets, followed by pouring 500 kg of lead. Sufficiently detailed recommendations for the manufacture of the fin are given in the article by A. S. Struzhilin “The half-ton “ST-28” ( “KiYa” No. 87 ). Before drinking lead, the body of the fin must be buried in the ground along the root section and the soil should be compacted tightly. On the finished fin, welded seams are cleaned with emery, the surface, if possible, is sandblasted and primed with minium on drying oil in 2-3 layers.
Tourist version of the sailboat
The tourist version of the sailboat is designed for operation by a family crew of three to four people. It provides for a transom stern, a straight closed cockpit and an enlarged cabin (the outlines of this option are shown in dotted lines on the theoretical drawing). Sailing armament - type 7/8, with one pair of rigidly fixed spreaders deflected into the stern. The shrouds are 300 mm aft from the mast step axis, so no backstays are required. The area of the mainsail is somewhat reduced (the mainsail from a Soling class sailboat can be used), and the staysailb enlarged. The mast and boom in this embodiment can be made from a pipe 95X2 or 110X2.5 (AMg6N alloy). In the touring version, sails and supplies are stored under the cockpit in an isolated afterpeak room on the starboard side. There is a wardrobe and a flush toilet can be installed. On the left side in the "coffin" is a bunk. The central part of the sailboat is occupied by a salon with two sofas and a dining table, which can be lowered at night to form a double bunk. On the starboard side there is a galley with a gas stove, a sink and a cutting table. In the bowsailboats can be equipped with a small but cozy double cabin. In family sailing, she will successfully fulfill the role of a nursery.
The hull design and the location of the frames are no different from the sports version, only the shape of the cutouts in the transverse bulkheads has been changed. The length of the cockpit is quite sufficient to accommodate the entire crew; if necessary, it can be accommodated for the night. For ease of operation in rivers and lakes, it is better to equip the tourist version of the ST-251 with a small-scale ballast fin, due to which the total draft of the sailboat will be 1.1 m. a fewis large to compensate for some reduction in hydrodynamic efficiency due to the reduced span.
In the sports version, a balancing steering wheel with a stock made of a steel bar with a diameter of 50 mm of the Kh18N10T brand is provided. It is also possible to make a stock with a diameter of 60 mm from the AMg61 alloy, from a 47X5 pipe or a ∅40 mm rod from the VTZ-1 alloy. The rudder feather can also be made of fiberglass 2.5–3 mm thick, with the inner cavity filled with foam plastic or a welded structure made of light alloy. In the tourist version, the sailboat is equipped with a hinged rudder - a simpler design, but easily damaged during parking or unsuccessful mooring. Therefore, it is recommended to doero easily removable from hinges; this will also come in handy in the case of landing the sailboat astern on someone else's anchor rope.
Careful profiling and finishing of the rudder blade and fin should be given special attention - after all, the steepness of the sailboat's tack and its speed on all courses relative to the wind depend on their effectiveness. The surfaces of the leading edge of the rudder blade and fin should be close to polished.
For successful performance in competitions, the sailboat must be equipped with an effective spars, sails and devices for adjusting the sailing rig. The flexible spars made of a weldable aluminum-magnesium alloy AMg6N are considered optimal; 85X2.5 pipe or similar can be used for mast and boom. It is important that the moment of inertia of the cross section is not less than to ensure the longitudinal stability of the mast and not too much higher, otherwise the mast will be too rigid. The top of the mast for a length of approx.2.55 m must be made conical with a diameter of 40 mm at the top. To do this, using a cutter, a wedge-shaped cut is made on the front side of the mast blank, the edges of the cut are bent on a cylindrical mandrel to a gap of 0.5-1 mm along the entire length, then the groove is welded by argon-arc welding. At the same time, it is necessary to take measures against excessive deformation of the workpiece from the heat generated during welding: fix the pipe to a rigid base, place a steel rod or copper plate under the seam from below, weld it in small sections in a reverse-stepped manner. TJust as carefully, the lipase pipe should be welded: for its strong attachment to the mast, an intermittent seam in sections of 15 mm through 150-200 mm is sufficient.
The boom can be made of rectangular section - from two aluminum channels with side walls welded or riveted to them from strips 2-2.5 mm thick. In this case, the measurement rules allow a maximum section height of 185 mm without a penalty addition to the racing score.
The design of the spinnaker boom and its equipment can be borrowed from racing sailboats of the Soling or Dragon class with little or no change.
All mast and boom fittings must be made of stainless steel to avoid increased corrosion; turn pulleys from aluminum, textolite or caprolon; ducks to make cast or milled from aluminum alloys. If you need to fix any part with screws, you need to weld an overhead aluminum bar 3 mm thick to the mast or boom and make threaded holes in it for the fixing screws.
The standing rigging of the mast is desirable to be made of cables twisted from stainless steel wire. True, such a cable is difficult to access, therefore, a rigid cable made of galvanized steel wire of design 1X19, 7X7 or 6X7 + OS can also be used.
An important role in regulating the profile of the mainsail by changing the bending of the mast is played by the backstay and backstays. On the given sketches, two options for wiring the running rigging of the backstays are offered. Both have separate waists for adjusting the tension of the lower backstay; the total tension of the backstay in the first version is carried out with the help of powerful six-pulley hoists, and in the second, capstan-type winches are used for this purpose. Separate hoists are needed to tension the backstay.
In addition to the winches mentioned, two more for the sheets of the front sails and two for the halyards will be required. You can make them using, for example, the drawings given in "KiYa" No. 15 or No. 90 . The running ends of all the halyards are attached to the wedge stoppers at the aft edge of the cabin, so that the crew can carry out all manipulations with the sails without leaving the cockpit.
The sailboat deck, according to the class rules, must be fenced with a 450 mm high lifeline with a rigid railing in the bow. To stop the legs in the spans between the railings, it is necessary to fix low wooden stops-bulwarks of a trapezoidal cross-section 25-30 mm high to the deck.
The built sailboat must meet the requirements of the quarter-ton class rules, i.e., have an IOR racing score in the range of 5.3-5.5 m. On the theoretical drawing, the dash-dotted line indicates the position of the waterline in the measured state, i. all standard equipment and sails in the places provided for them, but there is no crew, clothes, water supplies and provisions. If the boat is going to sit with a different trim, the measured trim can be corrected by moving the internal equipment (batteries, outboard motor, anchor)., gas cylinder), as well as placing on the bottom of the internal ballast of lead or cast iron ingots. In order not to go beyond the racing score, it is necessary to familiarize yourself with the measurement rules regarding sails and rigging, otherwise you cannot avoid trimming the sails and the associated loss of the racing potential of the sailboat.
Notes from me as the owner and the one who designed the cabin layout for this sailboat.
In general, it is useless to shield the latrine in a separate room on this boat. No matter how hard you try, this room will be too small to be able to unzip / zip up without leaving it. It turns out that this is more of a locker than a latrine. The cruising option in this form, as described by the developer, cannot be made convenient. My latrine is located under one of the bow berths, and between the bow berth on the port side and the aft berth (in the semi-coffin) on the port side there is a folding table. It turned out very comfortable, I recommend deat the same.
Between the starboard bow berth and the starboard aft berth is a washstand with a lid on which to sit. That. one more place near the folding table is provided.
The bow with bunks and a latrine is fenced off by a curtain.
It is better to make the stairs to the cabin lifting or easily removable, because. there is a huge empty compartment under the cockpit and it is necessary to provide easy access to it. I went on an experiment and made a large hatch in the cockpit floor for easy access to this compartment. It turned out very convenient, I do not know what I would do without it. In the first navigation on this boat, I mainly used a gasoline outboard motor and through this hatch in the cockpit floor it was convenient to get gas canisters.
Immediately behind the stairs to the cabin, half a meter aft, I have a stationary electric motor, which is a main engine for my boat. Batteries for it are located in the keel area, under the rear berths. In the compartment under the cockpit I plan to put a gasoline generator for driving under the engine for long distances.
The sailing qualities of the boat are very good, even in my version of the "comfortable cruiser" the boat goes fast under sail. Managed easily, excellent steering.
I’ll add a couple of words about the motor: the project says that it is possible to place a light stationary engine under the cockpit. Given the size of the compartment under the cockpit, the maintenance of such an engine will turn into a headache. Even a small 2-stroke gasoline will be inconvenient to maintain, and if you need to quickly fix the problem on the water, in bad wind and wave conditions ... In general, I do not recommend putting a stationary internal combustion engine in boats built according to this project. Alternatively, you can put the outboard in a well, butwhen it is desirable to get confused with a folding propeller for such an engine.
BLDC motor (brushless direct current) with a power of 3 kW perfectly becomes stationary and does not require maintenance, while its weight is only 7 kg (the one I have).
An anchor for such a boat is suitable for a weight of 10-15 kg. I installed a 500W electric windlass - in principle, this is enough. I had a 12V 100Ah traction battery, weighing 40 kg - it pulled the windlass very poorly. When I replaced it with a lithium battery of the same capacity, the windlass turned like a helicopter and even pulled the boat to the anchor against the waves, without the help of a motor. At the same time, lithium turned out to be 2 times lighter.
Regarding the thickness of the rudder stock - not less than 40mm, better than 50mm.
It is desirable to install hatches branded. I tried to order home-made hatches, although they are cheaper, they leak (due to the fact that the wooden frame will sooner or later lead to moisture)
The stainless steel arch on my boat was not in the project, this is what I came up with myself. Practice has shown that this arch is very comfortable.