Home>>> Boat projects for self-construction>>> Motorboat «Rainbow-34» is a project of a high-speed seaworthy motor boat for sports swimming

Motorboat «Rainbow-34» is a project of a high-speed seaworthy motor boat for sports swimming

Motorboat «Rainbow-34» is a project of a high-speed seaworthy motor boat for sports swimming

Basic data of the «Rainbow-34» motorboat
Length, mm 3400
Width, mm 1700
Side height, mm 700
Body weight, kg 70
Motor power, hp 20
The speed under the engine is 23-25 hp, km/h about 60

In recent years, long-distance sports sailing on light motor vessels has become increasingly popular in our Leningrad sports clubs. Trips are made to Lake Ladoga, Novgorod and Vyborg, which allow improving the ability to control a high-speed vessel in rather difficult conditions — on an almost constant wave of large reservoirs, on busy shipping lanes. Many of our water-powered athletes fulfill the requirements of the sports classification and receive grades in chipboard.

Design group of the city sports and technical club of water sports (GSTK VVS) for several years he has been working on the creation of motor boats specifically for such sports swimming, in which high speed with the use of common outboard motors would be combined with a sufficiently high seaworthiness. Such vessels include the Raduga boats (see, for example, Sports and recreational motorboat «Rainbow»).

Offered to the attention of readers a new sports and tourist three-seater motor boat «Rainbow-34» was built by the master of sports A. Shcherbinin and has already been tested comprehensively. On her «account» several difficult sports trips, participation in parades of athletes and even in the arrival of motor boats of the SB class at the races of the Leningrad regatta «Golden Oars», held, as usual, on the turbulent Bolshaya Neva. In addition, the «Rainbow-34» was used for walks and official trips, maintenance of training and towing of water skiers.

The collection «Boats and yachts» has repeatedly published materials about recreational sports boats of minimal dimensions. It is no coincidence that such constructions as G. Malinovsky's «Moskvichka» or V. Weinberg's experimental boat (see No. 45 of the collection) enjoy undoubted success. The «Rainbow-34» motorboat also belongs to the class of mini-motorboats, the construction, transportation, storage and repair of which are most accessible to the bulk of water tourism and sports enthusiasts. It is 0.35 m shorter than the first «Rainbow», but at the same time 0.30 m wider and 0.22 m higher than it.

The keeled shape of the contours of the high-sided seaworthy hull, which has already become common, has been applied with longitudinal splash-bumpers and the collapse of the sides along the entire length in combination with a flat aft section of the bottom — a «ski». Such contours make it possible to ensure, with very good speed qualities, a soft — without large dynamic overloads — running on excitement, safety when rolling on circulation, good habitability (the cockpit is equipped with two sleeping places, closed with an awning).

Theoretical drawing and general layout of the «Rainbow-34» motorboat

Theoretical drawing and general layout of the «Rainbow-34» motorboat
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Table of plasma ordinates of the «Rainbow-34» motor boat
Line frame no.
1 2 3 4
  Heights from OL, mm
Side — LB 740 700 617 500
Cockpit 784 744 661 544
Redan R-1 174 73 15 0
Redan R-2 302 199 140 125
Redan R-3 430 325 265 250
  Half-width from DP, mm
Side — LB 682 823 850 801
Cockpit 482 623 650 601
Redan R-1 179 221 230 230
Redan R-2 348 425 448 450
Redan R-3 520 627 667 670

Dimensions of the redans in cross sections
Redan frame no.
1 2 3 4
P-1 x
P-2 x
P-3 x

When installing the «Whirlwind» or «Neptune» motor with a «racing» two-bladed propeller (pitch 340-360 mm) on a motor boat with one driver, it is possible to reach a speed of about 60 km/h. For comparison, we mention that the speed standard of the I category for the T-500 class at a distance of 5 miles is much lower — 42 km/h.

The design and construction technology of the housing are similar to those repeatedly described in the collection. On a sheet of plywood, using the table of plaz ordinates, it is necessary to build the outlines of shp. 1, 2 and 3 and draw all the elements of the boat set. Having transferred the necessary lines to tracing paper, transfer the marking (pricking with an awl) to the material — bars and plywood. Assemble the finished parts directly on the plywood plaza, lubricating the knits and ends of the bars (futoks) of the frame frame with epoxy resin. Having laid out the details of the frame, grab each with two thin nails to the plaza. Put the knits in place and «bait» them with nails, then, carefully lifting the frame with a chisel, put the knits on the other side of it, punch the nails through, remove and turn the frame over and immediately bend the ends of the nails.

The design of the hull of the motor boat «Rainbow-34»

Hull design of the motor boat «Rainbow-34»
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1 — keel 20x40; 2 — stringer 13x25; 3 — stringer 10x30; 4 — stringer 10x20; 5 — podlegars (seat support bar) 10x30; 6 — stern seat, δ=4; 7 — seat cushion 40x50x450 (foam rubber in a textovinite cover); 8 — the bottom of the engine niche, δ=2; 9 — cracker 15x20; 10 — coaming, δ=6; 11 — rail 30x40; 12 — aft seat back 10x100x450; 13 — awning arc, pipe Ø15-20; 14 — plexiglass δ=4-6; 15 — cockpit frontal sheet, δ=4; 16 — removable shield, δ=4; 17 — beams 30x15; 18 — nose seat, δ=4; 19 — rail 10x15; 20 — stitching of the shp. 1½, δ=2; 21 — frame rail 15x45; 22 — filler δ=15; 23 — bar 4x40x150 (4 pcs.); 24 — beams 15x30; 25 — sewing shp. 2, δ=2; 26 — knits, δ=2; 27 — rack 10x15; 28 — bottom lining, δ=6; 29 — cheekbone lining δ=4; 30, 31 — side and deck trim δ=3; 32 — transom trim, δ=4; 33 — filler rail, δ=20; 34 — board 20x125; 35 — sheet δ=4; 36 — transom binding on the sides, 20x30; 37 — bottom branch 20x45; 38 — plywood, δ=4; 39 — placeholder, δ=20; 40 — bar 40x15x400; 41 — plywood δ=4; 42 — piano loop.

The design of the hull of the motor boat «Rainbow-34» — frames

Hull design of the motor boat «Rainbow-34» — frames
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the designation of the positions — see «The design of the hull of the motor boat «Rainbow-34» above.

After assembling all three frames, place the DP line and the control waterline on them (from the OL at a distance of 500 mm). Along this control line, nail the shergen-bars with a width of 50-70 mm.

It is necessary to manufacture the transom using the dimensions of the working drawing, which already takes into account its slope.

The hull of the boat is assembled in the up position with the keel. On the slipway (two boards placed on an edge), the position of the frames and transom is marked. The frames are put in their places with a check on the diametrical plane with a plumb line, and along the horizon of the control line with a hose level. Having secured the verified transverse set, insert the longitudinal ties — keel, stringer and stiffeners. Before installing the skin, it is necessary to put a bulkhead on shp. 1 ½ and a recess niche node.

The plywood sheets must be pre-cut and glued «on the mustache», connecting them in a belt for the entire length of the boat. Then the finished sheets are laid on a carefully ground set, the details of the set are outlined from the inside, after which the sheets are removed to trim the allowance and drill holes 1-1.5 mm in increments of 50-70 mm for fasteners. The cladding is placed on epoxy resin with nails pressed «into the bend» along the longitudinal set and screws on the frames and transom.

The bottom, transom and sides must be thoroughly sanded and plastered from the outside, and then pasted with one or two layers of ASTT(b)-C2 fiberglass on resin. The pretreated redans and the splash guard are placed on the already pasted body and, in turn, are themselves pasted with strips of fiberglass.

Before sewing the deck, it is necessary to glue the seat body removed from the slipway and turned keel down and lay the foam between shp. 1 and 1, 2 and 3 to the height of the floats. The foam and the bottom from the inside between shp. 3 and the transom should be pasted with fiberglass. From the inside of the body, it is better to glue the transom around the perimeter with a «wet square» — a strip of fiberglass 80-100 mm wide.

The steering wheel, drum, pulleys can be made according to the drawings published by on this page. The remote control is conveniently located, as shown in the general drawing. Both navigators should be launched on one side.

To ensure unsinkability, it is necessary to lay foam blocks on the sides between the shp. 2 and transom; the volume of the foam should be at least 0.15 m.

Boat projects for self-construction

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