folding catamaran

Discussion in 'Multihulls' started by david ingles, Feb 6, 2015.

  1. david ingles
    Joined: Sep 2012
    Posts: 7
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    Location: AUSTRALIA

    david ingles Junior Member

    this is a design for a folding pod cat, trailable width 2.2m sailing width 6m. The model is one-third scale. The beams scale up to 90mm diameter, which is very light for this beam. Fore and aft bending loads are absorbed by double diagonal stays which are not shown in this model.
    The design utilises down-angled cross beams with the idea to eliminate bending load and leaving compression load only (see related post on folding trimarans and pod cats). Compression load is reduced by making the angle between the beams and the water stays as large as possible. This is achieved with the centre pod design which has lugs top and bottom to increase this angle.
    The beams slide in an out in boxes which are allowed to tilt slightly on folding. Detail of the boxes is shown in the photos.
    Twist can be an issue; my first attempt had a lot of twist when holding up one corner. I reduced twist by strengthening the water stays and adding extra bolts to the inboard ends of the beams (they originally had only one). The pictures show that twist is now controlled.
    One hull is displaced slightly behind the other in this model, to allow folding. This could be avoided if the hulls were purpose built. Only the hull/beam attachment points would be displaced.
    Ideally the hulls would be angle outwards for best sailing lines. The model omits this feature.

    Attached Files:

  2. rcnesneg
    Joined: Sep 2013
    Posts: 456
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    Location: Utah

    rcnesneg Senior Member

    The main hull needs to be slightly below the amas. You could make the main hull much deeper I suppose. Looks like you came up with a good folding mechanism! Thanks for sharing!
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