flat vs convex surfaces

Discussion in 'Multihulls' started by lucdekeyser, Oct 4, 2024.

  1. Rumars
    Joined: Mar 2013
    Posts: 1,915
    Likes: 1,205, Points: 113, Legacy Rep: 39
    Location: Germany

    Rumars Senior Member

  2. gonzo
    Joined: Aug 2002
    Posts: 17,259
    Likes: 1,924, Points: 123, Legacy Rep: 2031
    Location: Milwaukee, WI

    gonzo Senior Member

     
  3. lucdekeyser
    Joined: Aug 2004
    Posts: 210
    Likes: 18, Points: 18, Legacy Rep: 51
    Location: Belgium

    lucdekeyser Senior Member

    Thank you for these finds. These are very interesting examples, indeed. The owners seemed delighted. Performance was not their priority. I am very curious about their weight, though, to compare with more traditional builds. Comments from 2009 on this forum did not clear that up.

    From here, the theoretical exercise may be to consider how to get rid of the remaining curves, one by one, starting with those below the waterline. Like, cats need rocker, proas don't. How assymetrical can multihull bow entries be? Have one side flat and curve the other one doubly? Can this other side be an oblique flat surface instead? If the sides flare upwards, how to fit the single oblique flat side of the bow? How much is the penalty for not flaring the sides?
     
  4. lucdekeyser
    Joined: Aug 2004
    Posts: 210
    Likes: 18, Points: 18, Legacy Rep: 51
    Location: Belgium

    lucdekeyser Senior Member

    That is a given. Would you be so kind to comment on an earlier conjecture about the guestimated trickle down effect on the remainder of boat building costs
     
  5. gonzo
    Joined: Aug 2002
    Posts: 17,259
    Likes: 1,924, Points: 123, Legacy Rep: 2031
    Location: Milwaukee, WI

    gonzo Senior Member

    It is not a guestimeated trickle down effect, but an estimate based on the experience of building dozens of boats. The hull of a boat cost ranges at 10-15% of the total build cost.
     
  6. DogCavalry
    Joined: Sep 2019
    Posts: 3,314
    Likes: 1,676, Points: 113
    Location: Vancouver bc

    DogCavalry Senior Member

    Okay, now it's getting useless. Mortgage your house, build a proper boat, and a flat surface boat, and come back with the financials in a spreadsheet.

    And start a new thread, because I've unfollowed this one. DC out.
     
    BlueBell likes this.
  7. lucdekeyser
    Joined: Aug 2004
    Posts: 210
    Likes: 18, Points: 18, Legacy Rep: 51
    Location: Belgium

    lucdekeyser Senior Member

    That is dozens more than I have. Point taken.
     
  8. gonzo
    Joined: Aug 2002
    Posts: 17,259
    Likes: 1,924, Points: 123, Legacy Rep: 2031
    Location: Milwaukee, WI

    gonzo Senior Member

    The percentage of cost of the hull vs the total build diminishes as boats get bigger and more luxurious. For example, a megayacht may have several million dollars of artwork in it. Also, expensive items like gold plated hardware, fancy plumbing fixture, specialty marble, etc., far exceed the cost of the hull.
     
  9. lucdekeyser
    Joined: Aug 2004
    Posts: 210
    Likes: 18, Points: 18, Legacy Rep: 51
    Location: Belgium

    lucdekeyser Senior Member

    I was focusing on 40+ cruising multihulls which I guess range from about 350K - 1250K $. Even a good proportion of the higher ends is made in lower wage countries but still using off the shelve relatively expensive hardware and machinery from reputed manufacturers. Do we know how much cheaper these builts are, more or less?
     
  10. gonzo
    Joined: Aug 2002
    Posts: 17,259
    Likes: 1,924, Points: 123, Legacy Rep: 2031
    Location: Milwaukee, WI

    gonzo Senior Member

    I can't think of any 40+ foot catamaran that sells for 350K. Do you have any examples?
     
  11. lucdekeyser
    Joined: Aug 2004
    Posts: 210
    Likes: 18, Points: 18, Legacy Rep: 51
    Location: Belgium

    lucdekeyser Senior Member

    A Warrham 42' costs less than 100K in building materials + 2000 hours + equipment
    Rumar's referencing to the Hermann Heinrich above
     
  12. gonzo
    Joined: Aug 2002
    Posts: 17,259
    Likes: 1,924, Points: 123, Legacy Rep: 2031
    Location: Milwaukee, WI

    gonzo Senior Member

    Sure, but that is like trying to sell Model T Fords. There is no real market for them. Also, that would be possible in a reasonably well equiped shop and skilled labor.
     
  13. Rumars
    Joined: Mar 2013
    Posts: 1,915
    Likes: 1,205, Points: 113, Legacy Rep: 39
    Location: Germany

    Rumars Senior Member

    You can't compare costs between amateur builds and professional construction, in fact you can't compare them even between amateur builds. One guy will buy all new Festool the other use his grandfathers tools. Accounting is a joke with most amateurs, the true cost and time isn't usually known. How many amateur boatbuilders do you know that log the time, gas and vehicle depreciation they incurred going to the hardware store to buy some sandpaper because they run out? Or the hours spent online trying to find a deal on some hardware or asking advice on a forum?

    As for material prices, what can I say. Imagine you're a small but successful yard, doing several boats per year. When your resin, glass, foam or ply orders each fill a semi-trailer the prices are different. Even the amateur can get significant price reductions if he orders a drum of resin or a pallet of plywood.
     
    TANSL, DogCavalry and BlueBell like this.

  14. lucdekeyser
    Joined: Aug 2004
    Posts: 210
    Likes: 18, Points: 18, Legacy Rep: 51
    Location: Belgium

    lucdekeyser Senior Member

    Let me share some of the conclusions from a similar discussion on another forum:
    1/ faceted designs can approximate to considerable extent the drag with curved designs 2/ flat designs would not offer building efficiencies 3/ the double ender transonic hull idea was expertly debunked.
    Thank you for your patience and indulgence. It was a good learning experience.
     
    DogCavalry and gonzo like this.
Loading...
Forum posts represent the experience, opinion, and view of individual users. Boat Design Net does not necessarily endorse nor share the view of each individual post.
When making potentially dangerous or financial decisions, always employ and consult appropriate professionals. Your circumstances or experience may be different.