Help needed in building the first boat (pedal powered)

Discussion in 'Boat Design' started by Shai De, Oct 3, 2022.

  1. slboatdesing
    Joined: Aug 2022
    Posts: 147
    Likes: 9, Points: 18
    Location: Maldives

    slboatdesing Senior Member

    Hello. I am interested in this project, just curious if you have a place to store and launch the boat? There are some nice nesting design plans around. I was planning some sort of electric boat, was thinking it might be easier to build and launch a boat over there.
     
  2. Tiny Turnip
    Joined: Mar 2008
    Posts: 871
    Likes: 283, Points: 63, Legacy Rep: 743
    Location: Huddersfield, UK

    Tiny Turnip Senior Member

    In terms of hull design, for a stable, general purpose boat, I would go for a catamaran (for stability) and making it as long as you can (length is not an enemy of stability, and would help in reducing pitching in waves, as well as higher speeds and greater efficiency.) up to about 18-20ft. Much beyond that and the drag from the wetted surface area of the hull starts to become a significant inefficiency. The factors which would tend, for me, to lead to a shorter boat would be ease of transport, storage, launch. I would look at a design that can be broken down into easily lifted components, which could be carried across a beach, say, and assembled at the waters edge. This might be separate hulls, cross beams, deck, seats, drives, steering gear. It should be straight forward to build narrow, fast hulls up to 18ft which are readily liftable. As you will have to build a mould to make a fibreglass hull, as Bajan Sailor says, it gives you a lot of extra work for a one off boat. I would work with plywood, 4-6mm plus strengthening where required for seats, drives, connections. A rectangular cross section is just fine - you can round the corners if you wish by planing and sanding. The hulls can be parallel sided with pointed ends in plan view, tapering to a point from about 2 feet in. The width and depth of the hulls should be determined by calulating the total weight of the passengers, gear, and materials, to give the required displacement. The total volume of the hull should be *at least* double the total displacement. (any other views on this? I'm no NA) So, as a back of the envelope example, ... (swapping to metric units - sorry, its my natural currency these days, and a touch easier.) If your 2 hulls were 6 metres long, with a taper each end 0.6 metres long, and were 0.3 metres wide, and 0.3 metres high, that would give a total volume of approximately 970litres. If your total boat weight, crew and gear came to 300kg, that would give you a draft of around 0.1metres, and a freeboard of around 0.2 metres. You might want a little bit more than that, and its easy enough to make the hulls a little bit deeper. The limiting factor to a higher hull is windage. I would emphasise this - the more boat there is above the water, the harder it will be to control and propel in wind, and humans just don't have the power to cope with it. Something along these lines should suit well enough for a general purpose pedal boat, and be quite easy and quick to make. There will be much more work in the detail of the drive system, steering system, and comfortable seating. Hope that helps, but there are other much more qualified folk here whose advice I would take if it is offered. Good luck!
     
    bajansailor likes this.

  3. slboatdesing
    Joined: Aug 2022
    Posts: 147
    Likes: 9, Points: 18
    Location: Maldives

    slboatdesing Senior Member

    There is a tri-maran design that gets up to speed, pedal + solar powered. See video.
     
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