Affordable seaworthy cruiser

Discussion in 'Boat Design' started by goodwilltoall, Jul 31, 2010.

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  1. goodwilltoall
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    goodwilltoall Senior Member

    From careful study, the proportions of Noah's ark have the qualities of excellent seaworthiness and efficiency. The design that I have come up with is 50' overall.

    The formula for The Ark is: length 300 x beam 50 x hull depth 30.

    Following above proportions, proposed cruiser dimensions above would be: length 50'-0" x 8'-4" beam x hull depth 5'-0".

    Hull shape is a bolger box, leaning towards leeboards rather than daggerboard for lateral resistance which makes it a sailboat.

    Hull draft would be about 1'-1" to 1'-4", this is just a rudimentary calculation.
    Of course this depends on loading and ballast, which depends on sail area and mast height.

    Bolger used low aspect sailplans for this type of hull, but for reasons of affordability, sails will be limited to marconi sails because they are so numerous second hand and can be bought for 1/10 the price of new.
    This will mean it will be a ketch and possibly trimasted.

    It seems absurd but construction will be home depot lumber, but not so absurd when you consider "quality builders" have used balsa core which is much more prone to rot and has virtually no strength to build high end boats (that surprisingly are still around and doing quite well).

    Epoxy resin and hardener bough in 55 gallon drums will reduce cost to $25.00 per gallon, will encapsulate the wood and will also be much better than polyester used to skin balsa.

    Will add more info upon request but overall cost can be kept under $12,000.00

    Attached Files:

  2. frank smith
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    frank smith Senior Member

    It could be done.
  3. apex1

    apex1 Guest

    Do you have access to the NA´s homepage or e mail?:D

    And who said the Ark was seaworthy?:confused:
  4. troy2000
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    troy2000 Senior Member

    I think he's talking about his own design, based on the supposed ratios of the Ark, rather than the original....
  5. goodwilltoall
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    goodwilltoall Senior Member


    The author of The Scriptures has no email address known to me. The design of the ark is known to have been seaworthy because the last eight people on the earth at the time it was used were saved in it.

    The principles of the ark's design using a long skinny hull for seakeeping are proven and desirable. Low freeboard which is 60% of beam width is also highly desirable, high windage is a reason many boat have stability problems. Designs such as this are very resistant to knockdown (sharpie type), known for sideslipping rather than fighting with the sea, also the fact it is very long would give it excellent AVS stability and recovery from a capsize.

    Bolger box hull was chosen because it gives maximum stability for beam size and most resistance to rolling (needed for narrow hull). Matt Layden of paradox fame believes that chine runners are what help with leeway, but inspection of hull cross section reveals almost plumb sides which naturally will have more resistance to leeway than a rounded hull bottom therefore, the
    90 degree chines will stay.

    The point of this thread is to gather knowledge on how to proceed efficiently building this boat and for others to use it for for traveling safely, efficiently, and perhaps as a viable alternative to living onboard.

    There are problems associated with using a 50' long hull such as longitudinal strength & docking. It would have been designed with no deckhouse for a stronger hull, but the galley & bathroom need to have standing headroom.

    Hope to have pictures posted soon.
  6. Pierre R
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    Pierre R Senior Member

    I have a minature picture of Raw Faith in my mind. :) This ought to be a good thread.
  7. sorenfdk
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    sorenfdk Yacht Designer

    Aren't you forgetting the reinforcement?

    A freeboard of 60% of the beam sounds extremely high to me.

    Length and AVS have only little to do with each other.

    How will no deckhouse lead to a stronger hull?

    Looking forward to see them!
  8. SamSam
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    SamSam Senior Member

    I have a few questions about this endeavor.
  9. messabout
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    messabout Senior Member

    The Ark of biblical description was not a sea boat. It had no propulsion and needed none as its mission was merely to float until the water went away.

    Enki, a babylonian god, gave instructions to Atram-Hasis to build a boat that was round and made of straw covered with pitch. Much like a huge coracle apparently. The Babylonian instruction may well have been a precursor to the familiar Hebraic one.

    Modeling a modern boat after the presumed dimensions from an ancient text is not the best way to start your project.
    W9GFO likes this.
  10. goodwilltoall
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    goodwilltoall Senior Member

    Drawings have been added to first post.


    As far as reinforcement goes, will try to eliminate if possible- if necessary will add just single layer of 6oz. to exterior. One roll sized 50" x 125yds. would be sufficient.

    Two methods of hull construction:
    1. As shown in cross section drawing, it will consist of 4 layers of 3/4" bottom, currently home depot has good quality exterior from South America at $28.00 sheet. Next step would involve 2x4 stringers with 2 layers of 3/4" attached. With this method reinforcement needed.
    2. Would involve taking 2x4 to 2x12 sized lumber and laying it on edge at a table saw and then cutting 3/8" strips. First and last strip would be layed longitudinally with second and third at 45 degrees. Final hull thick at sides would be 1.5". With three layers of epoxy barrier coating, would hope it is strong enough by itself. This would be the preferred method as interior look would be warm and pleasant.

    In regards to freeboard, look at drawing it will show just enough room for sitting through most of the hull. This is not considered high when most new
    27' footers almost have standing headroom.

    If you take a 8' beam boat and use typical proportions of length equals 3X beam, you come up with about a 24' boat. Now take that same hull and stretch it 6X and in an inverted position it will be much more unstable.

    Anytime you add ports, openings, deckhouse attachements to a square or tubular hull you lose strength. A much stronger hull can be made doing this but then you would need a 67'-70' long hull to get standing headroom and with the advantage of a flush deck.
  11. apex1

    apex1 Guest

    Sorry Goodwill,

    there is a lot of premature dreams and nonsense in your ideas. You should go for a proven design and follow the instructions when you like to go sailing in that vessel in a very far day.......................

  12. goodwilltoall
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    goodwilltoall Senior Member


    Can you give three of the most glaring mistakes you see in the design and explain. Other than the sailplan (which admittedly needs improvement), most principles applied to the design have come from other proven boats. Hope to
    figure out the problems and build soon.

    BTW, shooting for a displacement of 12,000 to 14,500lbs. with ballast ratio of 35%.

    The design can work as in just the last issue of Small Boat Journal Commodore Munroe espouses the virtues of shallow draft in his designs and as well as using inside ballast. He of course was much more knowledgable in these matters, but most designs use empirical evidence from the past to build upon, which will also be done in this design.
  13. apex1

    apex1 Guest

    No sorry,

    too busy to get involved in another step by step tutorial. Especially not interested in fighting solidly cemented preconceptions.

  14. goodwilltoall
    Joined: Jul 2010
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    goodwilltoall Senior Member


    I accept your refusal and have considered your advice to go with a proven design. Since you can not help in this endeavor I ask that derisive comments and negative comments stop. No hard feelings, just want to keep things focused on aspects that can help the design to become a sucesss. Thanks.

  15. EuroCanal
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    EuroCanal Junior Member


    13,000 lb for a boat that's 50 ft by an average beam of, say 6 ft. That gives an average draft of about 8 inches - kind of shallow for a sea-going craft. But it gives me an idea ...

    Instead of dagger boards you might consider hydrofoils (you will need to put them on out-riggers, due to the narrow beam of the boat). You'll need to reduce the weight further, so no ballast, keep cargo to a minimum (no elephants, giraffes, ..) and keep provisions to a minimum (a few loaves and fishes can go a long way).

    The hull shape looks to me to be very suitable for this idea (surely no worse than sailing it with dagger boards), and it will give you a certain feeling of rising up to the heavens as the boat lifts out.
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