Aluminum sailboat designs under 30ft.

Discussion in 'Boat Design' started by Vineet, Apr 25, 2021.

  1. Vineet
    Joined: Apr 2021
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    Location: usa

    Vineet Junior Member

    I am looking for full keel, heavier displacement aluminum sailboat designs that are under 30'. Does anybody here know of anything like that? The only one I have seen is Tom Macnaughton's Silver Penny, which is a design I am very fond of. I do want to find other possibilities as comparisons.
    Silver Penny 25
  2. bajansailor
    Joined: Oct 2007
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    bajansailor Marine Surveyor

  3. goodwilltoall
    Joined: Jul 2010
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    goodwilltoall Senior Member

    Douglass Pollard built Bolger's "Wolftrap", 30'-0" x 10'-11" x appro. 2'-6" draft. Full keel. Cruised extensively world wide for many years w his wife. Had only excellent remarks re: using aluminum rather than steel, the sailing speed and sailing qualities.
  4. goodwilltoall
    Joined: Jul 2010
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    goodwilltoall Senior Member

    Wolftrap was written about in "30 Boats" 20210426_143449.jpg 20210426_143433.jpg
    Very safe boat which is partly due to the low hdrm but a deck house could b added which would slightly change its wind age profile.
    Love the low draft and aluminum build
    bajansailor likes this.
  5. ExileMoon
    Joined: Oct 2009
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    ExileMoon Junior Member

    If you decide to use aluminum, it can be said that there are very few (ready-made) drawings, but it can also be said that there are many options (you have to modify it slightly).

    Because of the price of aluminum and the required skills, generally self-built ships are less considered to be built with aluminum. So there are fewer ready-made drawings.

    However, it is not difficult to convert the drawings of steel ships and plywood ships to aluminum plate manufacturing. For steel boats, it can be achieved simply by replacing all steel plates with aluminum plates of 1.5 to 2 times the thickness. You can easily find that such an aluminum hull is lighter than a steel hull. This is a great advantage, which will be reflected in the larger AVS angle of your boat, and the boat is more stable.

    It is slightly difficult to convert plywood boats to aluminum plates. For a round chine plywood boat (round chine is made by overlapping multiple layers of thin plywood), it is very troublesome to change to aluminum.
    Even if it is a polyline chine, about 40% to 50% of the thickness of the plywood aluminum plate is needed, which will increase the weight of the hull. You cannot use the principle of equal strength replacement to replace plywood with thinner aluminum plates, because this will cause some wall stability problems.

  6. TANSL
    Joined: Sep 2011
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    TANSL Senior Member

    Frankly, I do not believe (although I have not done any calculations) that this relationship is applicable to all cases.
    By changing the thicknesses, not only of the hull plates but also of the interior pieces, floors, longitudinal girders, etc ... the lengths of the pieces that are attached to them will also change. The conversion of steel to aluminum (plywood/aluminum) requires much more study and many more modifications than indicated.
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