how long should my keel be

Discussion in 'Boat Design' started by matheo, May 4, 2021.

  1. matheo
    Joined: May 2021
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    Location: australia

    matheo Junior Member

    I am interested in boat building and I realize a keel is an important part if not the most important part and I'm wondering how large my keel should be on a 6 m long old wood boat. I was thinking of making the keel 12 x 8 and frames 6 x 6 but then I realized it's too large for a 6 m long boat so now I'm wondering if a 8 x 6 with frames of 4 x 4 and also could you please give me some recommendations for nice and cheap good types of wood for boat building and can you please tell me the engine I require to run a beast of this size? By the way (width)x(length) all measurement are in inches(2.5 cm) and I'm planing on making a floor under the deck and a raised floor at the back of the ship for the steering wheel and I'm wondering if I have to add weight above the keel like cement or lead and what type of brass or bronze works best in this case.
    Thank you for you attention from a wanna be boat builder, me
     
  2. jehardiman
    Joined: Aug 2004
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    Location: Port Orchard, Washington, USA

    jehardiman Senior Member

    Welcome to the forum.
    Ok, way too many questions to adequately answer with the information provided. When you say "old wood boat", there are at least half a dozen different construction methods each with their own scantling and frame-and-space rules. If you are really interested in making a classic (i.e. early 20th century) wooden boat in the Aus/UK/US downeast style, get a copy of Yacht Designing and Planning by Chapelle and/or Elements of Yacht Design by Skene. Both are period, have scantling rules, and are available in print for about $20US each. A good investment. Or pay Will's shipping... Old Books for Cheap https://www.boatdesign.net/threads/old-books-for-cheap.65445/
     
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  3. bajansailor
    Joined: Oct 2007
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    bajansailor Marine Surveyor

    Following on from J E Hardiman's excellent advice above -
    Are you looking to restore an existing old 6 metre long wooden boat, or build a new one?
    If the former, do you have any photos that you can post of it?
    If the latter, what type of boat is it? Do you have a set of plans for it? If so, can you post any details?

    Re type of wood, it all depends on what shape your hull form is, and what type of construction you want to use - plank on frame, lapstrake, strip plank, plywood.......
    Please give us some more details.
    Re engine size required, this will depend on what type of hull form you have, what speed you want to achieve, and how heavy the boat is (or will be).

    I am looking forward to finding out more about your boat - she sounds interesting.
     
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  4. Mr Efficiency
    Joined: Oct 2010
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    Mr Efficiency Senior Member

    6m is still a fairly small boat, and there is no need to have timbers that would be more in place in an old road bridge. I assume you are not a speed freak, as a heavy boat is a slow boat !
     
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  5. Mr Efficiency
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    Mr Efficiency Senior Member

    I don't think a 6m carvel hull would be easy to find, I can't recall seeing one.
     
  6. jehardiman
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    Location: Port Orchard, Washington, USA

    jehardiman Senior Member

    Yeah, for a caravel boat that size with sawn frames, Chapelle gives a planking thickness of 1/2" and frames sided 3/4" x moulded 1" with a space of 7" (edited due to brain fart...6m, not 30 feet).
    Matheo...perhaps you should start at this .au site, I'm sure they can help you.
    The Wooden Boat Association https://www.woodenboat.asn.au/
    and
    Boat Plans and Building Tips https://www.woodenboat.asn.au/links/boat-plans.html
     
  7. jehardiman
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    jehardiman Senior Member

    Today, everyone is using glued strip or lapstrake for weight and ease, but back in the early 1900's many small boats were carvel ... peapods for a prime example.
     
  8. Old Stoker
    Joined: Feb 2020
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    Location: Australia

    Old Stoker Junior Member

    Try to find a book called Simplified Boatbuilding by Harry V Sucher.
    Or George Buehler's Backyard Boatbuilding.
    Good Luck. One of these should help.
     
  9. matheo
    Joined: May 2021
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    Location: australia

    matheo Junior Member

    hey i made a new post with a rough plan here is the link :
    rough plans for a boat https://www.boatdesign.net/threads/rough-plans-for-a-boat.65505/
    btw im new to this and its my first time drawing a boat plan so im not sure if it came out right
     
  10. bajansailor
    Joined: Oct 2007
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    bajansailor Marine Surveyor

    Matheo, it might be easier to keep everything under one thread, rather than starting new threads?

    Here is a copy of the sketch posted in the link that you mentioned.
    Matheo's design.jpeg

    Can you explain it to us please?

    Is this based on an existing boat, or is a completely new design?
    Is the sketch roughly to scale?
    If it is, it looks like it will not be very stable - most of the weight for passengers will be taken up by ballast low down, with no space left for you......
     
  11. matheo
    Joined: May 2021
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    Location: australia

    matheo Junior Member

    Now that you mention it, I believe I have not drawn it correct. It should be 1 section taler from the bottom so that you can have a 50cm gap for the ballast. Thank you for pointing it out.
     
  12. clmanges
    Joined: Jul 2008
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    clmanges Senior Member

    Matheo,

    I wonder if you've somehow mixed measurements in this drawing, but I can't imagine how such a thing could happen when you're using the metric system.

    It looks like a normal boat that has been severely compressed in length and width.

    Try drawing it again, keeping the height the same but making it wider and longer by, say, three times as much.
     
  13. matheo
    Joined: May 2021
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    matheo Junior Member

    Yeah I believe I did the measurements wrong; it should be a 6m boat 2m wide 2.5m high. The .5 is for the ballast 3.5 m high at the back and 3m high at the front. I'll have to redraw i.
     
  14. bajansailor
    Joined: Oct 2007
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    bajansailor Marine Surveyor

    I am still baffled by this design of yours Matheo.
    The sketch looks a bit like an old Spanish galleon, with a very high poop deck aft.
    What is the reason for this, on a 6 metre long boat?
    Most boats nowadays are higher at the bow than at the stern - but your stern is 0.5 m higher than your bow.
    Have you written up a 'Statement of Requirements' for this boat, detailing everything that you want this boat to be capable of?

    If not, how did you arrive at the 'Spanish galleon' look?
    What do you want this boat to be able to do?
    You mention an engine in your first post, so I am assuming that it will be a 100% power boat (ie no sails, like what a galleon might have).
     

  15. Mr Efficiency
    Joined: Oct 2010
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    Mr Efficiency Senior Member

    A 6 metre motor boat should not require ballast, but anything built along the lines depicted, would. And lots of it. It is just an unnecessary excursion away from the practical. You also introduce deep draught that is a limitation you are better without.
     
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