Dinghy design

Discussion in 'Boat Design' started by Brands01, Oct 30, 2009.

  1. Brands01
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    Brands01 Senior Member

  2. JLIMA
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    Location: New Bedford Ma.

    JLIMA crazed throttleman

    Looks similar to one I had a few years back, the one I had was a little less beamy and had less dead rise but otherwise were pretty similar. Mostly i rowed (used an antique pair of 8' oars very lovely, now on the wall of my workshop) but she handled very well with a 10hp out board but i never fitted her for sailing. I only used her as a tended for my old Penn Yan. I'm assuming she's about 10-13 feet long I'ma gonna level with you here, I don't understand metric very well. But from the pictures seems to be a not bad little boat, just a thought if you lessened the dead rise you would stiffen her up a bit, but it i don't know what you consider pretty protected. If it's anything like what i consider than you should be fine although for use under sail I would definitely say choose your rig wisely and rig her with a dagger board. Personally i like the look of the old Gaff rigged catboats but that's up to you.
     
  3. Easy Rider
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    Easy Rider Senior Member

    I like her a lot. But like JLIMA I don't think she's perfect. I'd leave the deadrise and reduce the rocker about 40%. And like JLIMA I'd like to see inches and feet. Brands, how do you make drawings like that of your skiff?

    Easy Rider
     
  4. lewisboats
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    lewisboats Obsessed Member

    freeship/delftship

    I would say reduce the flare of your first chine and widen the bottom some. You are looking at a fairly tender boat with the bottom that narrow...almost like a vee although not quite. If my calcs are correct you have a 6 ft long boat with a max beam of 33" and the bottom is around 14" wide. You are going to have a hell of a time getting plywood to bend as much as that top plank forward is curved and twisted in the bow area. Do a right click and check on the developability after reducing the resolution to high or medium. This will give a good indication of how cheap you can go on your plywood. The red areas are stress and if too big you won't be able to bend it without breaking the plywood or doing something like soaking or steaming it.
     
  5. apex1

    apex1 Guest

    The boat is 9´by 4´with some 8" draught. (when will you accept, the entire world is metric?)

    As Lewisboat mentioned the bottom is too slender, that is a tippy junk.
     
  6. lewisboats
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    lewisboats Obsessed Member

    OK...so I skipped a step in the calculating...you would too if a 110 lb (50 KILO!) dog was seriously attempting to get your attention!
     
  7. apex1

    apex1 Guest

    Ja Steve, I would!
    Though my Labrador / Dane mix was 74 kg (163.1404 lbs) and had a shoulder height of 72 cm (28.3465 in)
     
  8. lewisboats
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    lewisboats Obsessed Member

    Sounds like my Ex....I didn't say that!
    I hope you meant Chinese Junk rather than the other definition (quick return to topic!)
     
  9. apex1

    apex1 Guest

    Could I possibly have that a bit less cryptic? Who, why, what sounds like your Ex?:confused:
     
  10. Brands01
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    Brands01 Senior Member

    Great guys, thanks for the suggestions. I'll make some changes and repost the pics - along with some imperial dimensions :)
     
  11. lewisboats
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    lewisboats Obsessed Member

    Never mind...it wasn't on topic
     
  12. JLIMA
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    Location: New Bedford Ma.

    JLIMA crazed throttleman

    These are just a thought to consider, similar to the one you posted. S&G construction 1/4" ply with a 1" thick transom. The bottom is wider and the look is similar just something to consider, although I'm sure I'm going to catch some flak from some around here for the design it's one that worked for me and after 6 years is still solid and hasn't killed me, capsized or misbehaved with use in the chop of Buzzards Bay. Just something to consider.
    New model.PNG

    New model 1.PNG

    New model 2.PNG

    New model_Linesplan.PNG
     
  13. JLIMA
    Joined: Oct 2009
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    Location: New Bedford Ma.

    JLIMA crazed throttleman

    Also I put it in metric for you. Yes even I can learn something new.
     
  14. nordvindcrew
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    Location: Marshfield massachusetts usa

    nordvindcrew Senior Member

    comments

    I like your design a lot. I also think you should get rid of a lot of the rocker in the bottom. The flaring garboard panels along with the flare in the rest of the hull will provide a lot of reserve bouyancy. Can't comment on a sail rig, but it should be possible if a daggerboard is added and the rig is kept small and low. Good luck!
     

  15. Brands01
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    Brands01 Senior Member

    Revised nice little skiff

    Here is a revised version.

    I've taken on board all the comments. This version has about 30% - 40% less rocker, a wider bottom panel, and I've removed a tiny bit of flare. You can see from the developability picture that there shouldn't be any problem getting the plywood to meet any of the curves.

    I've also added about a foot (since when did anyone designing a boat go back to the drawing board and not add any length?), so its now close to 10ft.

    AND ... I've even put it in imperial!

    Barney

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