One of the main tasks of a designer in any vehicle is to make it easier. Of course, not at the expense of stiffness and strength.
If to speak about building of small vessels, the most modern materials available it is possible to consider the aluminum (for the frame) in combination with the composition of the foam, fiberglass and epoxy adhesive. This technology is well known, and to add to it, it would seem, nothing.
However, I found a very simple and cheap solution with a slight increase in weight (2-4 kg) to increase the strength by several times, simultaneously adding and stiffness. For this riveted frame made of duralumin tubes (ski poles, already the beds-cots, etc.) braided plastic twine (this often happens in hardware stores — bays at 400 m, with a mass of about 1 kg). On a boat with a maximum length of 4000 mm, a maximum width of 1250 mm and the lowest height of the midsection from the OL 490 mm left 2 bays. That is, the weight of the boat mesh added about 2 kg.
My boat with the snap-in under the oars, bow and stern decks and the awning has a mass of about 80 kg Sailing rig with two side surcame to this value are not included. There is a possibility of reducing weight at the same size 10-15 kg, because I used too much epoxy putty for bonding foam fore and aft compartments (for imparting buoyancy in the flooded condition). Foam inside, covered side above the waterline.
The specified strength of the cord is very high. Made from a mesh reinforces the skin and gives it a good durability of the trampoline. It goes without saying that to obtain such a mesh cord needs to weave vnatyazhku.
It looks like the cross section of the boat-braids (A — no plating of the hull with foam, B — variant with a foam plastic layer between the fabric and fiberglass). Bottom left shows one of the cells framed, braided plastic twine.
This figure shows the covering of a boat-braids (from the inside). Visible aluminum elements of the frame of the boat, the mesh from a plastic twine strapping the stringers and medeley of the keel.
There are two ways of using this grid. At first after making a duralumin frame, the cord is tied only around the stringers, as if repeating frames. Then perpendicular to them last (after one up and down) the longitudinal threads, i.e. parallel to the stringers. In this case, the mesh forms a conditional tangent surface on the outside of the frame.
Further, the mesh cover impregnated epoxy fiberglass: 3-4 layers on the bottom and on the sides above waterline — 2-3. Of course, for imparting buoyancy filled with water the boat needs the bow and stern parts to provide sealed compartments, or fill them with foam.
The second method although more time consuming, but allows you to get the most optimal results. It differs in that the mesh forms the inner tangent of, say, the surface relative to the frame. In this case the longitudinal threads of the grid wrap around each frame, and transverse — each stringer. Thus, between the stringers is obtained throughout the length of the slots that you want to sew the foam at the level of stringers. To increase stiffness and further range of amenities in the manufacture of the sheathing must be filled in exactly fitted strips of foam glue. Preferably, the strip was wedged tightly between the stringers and did not drop out. Before coating the fiberglass outer surface must be well leveled with the plane, drachevym with a file, emery paper.
The value of the second method is that the foam part of the skin would be between a durable mesh and a layer of the obtained glass fiber. And very important: since the twine tied around all the frames and stringers, the frame and trim are one.
To produce a net gain (with cells of 25X25 mm or 30X30 mm) for a week and a half, if you spend two hours daily. To make the grid manually is not easy, so for convenience take the Shuttle, similar to that which knit fishing nets, or just stick the winder with a width of 20-25 mm. Length of twine on one filling should exceed in one case the length of the frame and the other the length of the stringer (plus cut, in order to secure the end)
Both methods provide an epoxy glue, of course, the outer and inner surfaces of the sheathing: glue impregnates the mesh twine and sticks it to the foam.
Boat-network in the stage of completion of the works. Kiel used from the kayak “Taymen-2”, the lower part of the keel is hand made. Tank’s filled with tightly Packed foam; the bars of the top layer glued together with epoxy putty.
I made the boat has a pointed stern, as intended for hunting large reservoir with reeds. It provides, in addition to foam-filled compartments, two sealed trunk. The stem, sternpost, sockets for oarlocks, mounting for a wheel — steel, which is slightly weighted design. Stern and bow decks of the protection of 2 mm thick duralumin. Frame has 10 frames 12 and stringers; the keel of the “Taimen-2”, bottom reinforced duralumin pipe Ø 40 mm curved according to the ordinate of the drawing. So if you want to reduce weight with a slight weakening of the rigidity is possible, reducing the number of transverse and longitudinal ties, steel parts. Decks can be made of, impregnated with hot linseed oil the plywood (and only on the size of the compartments with the foam). Valid facilitate and keel. The only items of steel will remain nests under the oarlocks. The weight of the boat will not exceed 65-70 kg.
B. WALCH, lecturer of labor studies, Krasny Liman, Donetsk region.
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