Solid "rib tube" dory

Discussion in 'Boat Design' started by George T, Aug 15, 2020.

  1. George T
    Joined: Nov 2019
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    George T Junior Member

    Hi all,

    Had an idea whilst browsing eBay and seeing a "work boat" of about 30 ft with a set of solid rib style tubes on a dory type hull, I was wondering if this would be scalable down to a 17 - 29ft dell quay or Wilson flyer type dory hull using fibreglass box section mounted around the gunwhales and filled with two part foam for buoyancy and impact protection, please let me know whether this is ridiculous or not, will try and get some drawings done and post an update soon.

    Many thanks.
     
  2. Tiny Turnip
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    Tiny Turnip Senior Member

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  3. gonzo
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    gonzo Senior Member

    You would be raising the center of gravity quite a lot. What do you want to accomplish?
     
  4. George T
    Joined: Nov 2019
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    George T Junior Member

    Was hoping to have them so that they sat on and partially covered the gunwhales like a normal rib rather than above them, this was to try and minimise a rise in CG, my aim is to provide better stability and seaworthiness especially in larger waves than a typical dory, this is part of an approach to the design in my earlier thread about a safety/support boat for working with sport boats such as sb20's and j80's in the solent and around the coast of Britain
     
  5. bajansailor
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    bajansailor Marine Surveyor

    George, I think that Dell Quay and Wilson Flyer 'dories' already have more than enough positive buoyancy between the inner and outer fibreglass skins, in similar fashion to Boston Whalers (?)
    In which case do you really need to add additional buoyancy (not to mention a lot of extra weight - and high up, as Gonzo notes above)?
    If you have a foam filled fibreglass box section around the gunwhales, you will still need conventional fenders, as the fibreglass will basically be similar to the hull itself. So you are not really achieving any more 'impact protection'.
    If you really want to go down this route, I think that TT's suggestion of using an HDPE collar like the Flugga boats would be more sensible (although no doubt a collar like this will be relatively expensive).
     
  6. George T
    Joined: Nov 2019
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    George T Junior Member

    Hi Bajan, the impact protection was more a case of a mild puncture proofing of the fibreglass as the foam will still hold some buoyancy even of the fibreglass is punctured, I am aware of the already substantial buoyancy of the dory designs, my thinking was more for when it gets rough and the tube style addition will be more stable? Also the normal hull would probably be a tad overloaded with the equipment needed for so.etimes 8 or 10 hours on the water with a minimum of 3 people onboard at once hence my thinking for extra buoyancy being needed? But I'm not too sure on that, again with stability I was hoping to attach them at the same level as normal rib tubes so only raising the overall freeboard by a few inches but providing stability like a normal rib tube? As I said, I will send some photos tomorrow morning to illustrate my thoughts
     
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  7. BlueBell
    Joined: May 2017
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    BlueBell "Whatever..."

    How about a bigger boat?
     
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  8. George T
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    George T Junior Member

    Had the option of a bigger boat been viable I would have simply left this thread before it was posted
     
  9. gonzo
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    gonzo Senior Member

    Give it more flare.
     
  10. George T
    Joined: Nov 2019
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    George T Junior Member

    Was trying to avoid major hull rebuild, planning on using an existing hull
     
  11. kapnD
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    kapnD Senior Member

    Pictures would help.
    Dory hulls have considerable flare throughout their length, providing lots of reserve flotation, a factor that has made them very popular with Inshore and offshore commercial fishermen for many years.
    As far as gaining “stability and seaworthiness” you’ll not gain much in that respect by adding height and weight to the equation.
    From your description of the situation, one can only deduce that you do indeed need a bigger boat, whether that’s what you want to hear or not.
     
  12. George T
    Joined: Nov 2019
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    George T Junior Member

    Just to clear up any confusion, in the UK a dory is the boat attached, not sure where everyone else is from but you seem to have a wildly different idea of what a dory is as you all seem to mention flare and to he like when there is quite evidently none in a dory (at least in UK terminology)
    upload_2020-8-16_20-54-31.png
     
  13. kapnD
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    kapnD Senior Member

  14. kapnD
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    kapnD Senior Member

    You guys are way off base calling a trihedral planing motorboat a dory!
     

  15. bajansailor
    Joined: Oct 2007
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    bajansailor Marine Surveyor

    Another classic example of the differences between American and English english :)
    In Britain the most popular brand name of the trihedral boats is Dell Quay Dory (and they were originally built in Dell Quay), and maybe as a result other types of trihedral craft (like the Wilson Flyer) also came to be known generically as 'dories'.
    In actual fact their nearest similar vessel is probably one of the original Boston Whalers.
     
    Last edited: Aug 16, 2020
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