Submarine “Afalina”. Building a hydrofoil boat
The hydrofoil “Afalina” is intended for walks and short (one or two days) trips on the big rivers and reaches where the probability of a meeting with the developed excitement is high. With the outboard motor capacity of 20-30 HP the boat can be used as a towing water skier for practicing elements of figure skating.
Basic data of the motorboat on the wings
Maximum length, m 4,42
The width of the deck, m 1,64
Width at the cheekbone on the transom, m of 1.18
Board height on a midship, m 0,68
Body weight, kg 130
Outboard motor, HP 14-30
The side profile of the boat is built in accordance with the so — called “shape of the trochoid” – the shape of the wave profile, which gives the silhouette of the ship a pleasant soft dynamics, emphasizing its speed and seaworthiness. Highly inclined flat surface of the windscreen gradually, in a concave curve, decreasing in height toward the stern, moving in a tight high coaming of the cockpit.
The layout of the vessel, the elements of equipment are no different from the repeatedly described in the collection of projects and there is no need to dwell on them. We note only that the seats on the boat rigid, folding and can be cleaned in the nose under the deck; the cockpit is completely free and here you can put inflatable mattresses or sleeping bags.
The steering wheel is proposed to be placed on the deck behind the windscreen on the left side so that the axis of the steering wheel is vertical. This arrangement facilitates access to the bow under deck space, simplifies the design of the body.
In my opinion, in conditions of minor excitement, the most effective use of the motorboat can be achieved by installing hydrofoils. The speed of almost any planing boat increases at the same time in 1,2-1,3 times or, accordingly, its load capacity increases without a significant drop in speed. In particular, there is a known case of access to the wings of a vessel weighing 800 kg under a 20-strong “Vortex”.
Theoretical drawing of the hydrofoil
Constructive longitudinal section and plan
hydrofoil motor boat
1-stem, pine, Lamin., 50X60; 2 — eptember, 20X50; 3 — BIMS, 20X50; 4 — stringer deck, 15X30; 5 — cnica bimova, viafara, 4X80X80; 6 — filler, δ = 20; 7 — cnica zygomatic, viafara, 4X80X80; 8 — partimers, 20X50; 9 — cnica flora, viafara, δ = 4; 10, 12, 13 — front panel, stainless steel. steel, 2X30; 11-windscreen, org. glass, δ = 5 – 8; 14 — fender, 20X30; 15 — side stringer, 15X30; 16 — support of the bottom ceiling, 20X20; 17 — Flor, viafara δ = 4; 18 Kil; 30X50; 19 — Carling, 20X30; 20 — frame glass, stainless steel. steel, δ = 2; 21 — polubes, δ = 20; 22-barkhout, pine 20X25 or ash 15X20; 23-lining, ash, 10X150; 24-stitching, air-fan, laminated plastic, δ = 2,5-3; 25-pillow, pine; 26-zygomatic chipper, 30X30; 27-zygomatic bar, 30X40; 28-longitudinal redan, oak, 30X60; 29-bottom stringer, 15X30; 30-glass-fencing, org. glass, δ = 5 – 8; 31 — brestoc, pine, oak, δ = 20; 32 — the covering of transom, viafara, δ = 6 – 8; 33 — filler-transom, δ = 20; 34 — the covering of the inner transom, viafara, δ = 4 – 6; 35 — knize, oak, laminar., δ = 20; 36-stand, oak, 25X100; 37 — sheathing bulkhead, viafara, δ = 6 – 8; 38 — BIMS, pine, ash, δ = 20; 39 — bearing cladding, 20X15; 40 — Midel’veys, 15X50; 41 — pillows, δ = 20; 42 pillow under glass, 20X30; 43 — plating bead, viafara, δ = 4 – 5; 44 — the hull bottom and deck, viafara, δ = 5 – 6.
The section on frames
Symbols-see on the longitudinal structural section.
Wing device “bottlenose Dolphins” consists of a nose V-shaped wing, crossing the surface of the water, and the aft flat lightly loaded wing. The nose wing is attached to the body with curved bolts, under which the washers are placed such a height that the head-handle is directed downwards. If the wing is made of light alloy, the thickness of the profile should be increased to 0.1 width of the wing. In any case, it is useful to put the bracket, based on the keel, under which the desired height of the lining is selected in place. The aft wing is attached to the parallelogram on which the motor is hung. The design allows you to raise and lower the motor and wing as necessary. The springs are selected so as to balance the weight of the motor with the wing, and then in the lowered state the system is held only by the screw stop.
Nose wing design
1 — wing, harvesting 15X220; 2 — lateral stand, 10X80; 3 — average stand; 10X100;
Aft wing design
1-wing, 10X130; 2-rack 10X100; 3-sub-motor Board; 4-screw M4X60; 8 PCs.; 5 – arm (square with cut shelf); 6-spring; 7-bolt M10X20; 8 – plate δ = 3;
9-sleeve Ø 40X5; 10-tube Ø 20X5, L = 30; 11-stop, weld from rod Ø 10 mm;
12-bolt M10H30; 13-washer 10; 14-washer 14; 15-nut M10; 16-spring earring, δ = 2;
17-sleeve Ø 14X1, 5, L = 13.5, brass.
Here is only the easiest way to attach the wings to the body. More successful, but also more complex system is described by A. S. Chugunov in the collection № 26 (1970). The angles of the wings are selected by successive approximation, but for the first release of the nose wing, it is necessary to set the angle of attack to the horizon minus 1-2°, aft +1°.
Fuel tanks (we recommend the use of regular tanks to the Neptune engines) are installed behind the stern waterproof bulkhead, then in the case of accidental spilling of the mixture into the cockpit does not get gasoline and oil. It should be borne in mind that the boat will quickly come to planing with a more nasal alignment, and after overcoming the hump of resistance, the cargo can be shifted to the stern — this will affect the speed a little.
A few words must be said about the contours and propellers. “Afalina” – a typical vessel with a” deep V”, but to improve the strength and hydrodynamic qualities of the hull bottom branches of frames given a significant bulge. At low speeds, the boat behaves like a normal keeled boat: strikes on the strongly keeled bottom at the cheekbones are not great, but at full speed with a small load the boat goes on an almost flat strongly elongated section of the bottom with optimal angles of attack and is not sensitive to changes in alignment.
In the first approximation, you can pick up the screw, using the recommendations of the table (motor ” Vortex-M»):
Load screw Pitch, mm Diameter, mm
On the wings
2 people 380 240
4 people 300 240
2 people 280 240
4 people 220 240
1 person + 1 water skier 240 240
Three-blade propellers with a disk ratio of 0.55 are recommended.
In conclusion, we note that the stem is necessary to glue strips of a thickness of 6-8 mm, and after treatment to connect with a keel length of not less than 300 mm. Fasteners from non-ferrous metals can replace conventional steel, but the holes for the screws and bolts should be poured oil paint. VIAM-B3 glue can be replaced with epoxy adhesives or K-17 glue, sometimes called “synthetic joinery”, for which oxalic acid is used as a hardener.
The body of the motorboat is recommended to paste over with fiberglass and paint with epoxy enamels. In the absence of such enamels, pentaftal enamels or oil paints are used, but the body will have to be sanded beforehand.
Glue VIAM-B3 can be used to cover the bare body, but then it is added 10-15% alcohol and 3-4% acetone. This part of it penetrates between the fibers of the wood and cans securely its. When polymerization adhesive film is stretched and the surface is smooth and shiny. Over time, the coating becomes dark cherry color.