Rigid Boat

Discussion in 'Boat Design' started by SummerSchool, Jul 17, 2021.

  1. SummerSchool
    Joined: Jul 2021
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    Location: Maryland

    SummerSchool Junior Member

    Hello I am a new member of the group and have limited boat building experience. I’ve built a kayak and a rowing dinghy. I have done some fiberglass work on my boat and some fiberglass pieces for different parts and repairs. So my next project I am looking into seeing if it it possible to do a home built dinghy like a “Rigit Boat”. If you are not familiar woth this boat I will include a link. Basically it’s a fiberglass boat that is the shape of a Rigid Hull Inflatable. It claims to have all the advantages of stability of an inflatable with the advantages of tracking boat handling and durability of a traditional fiberglass boat. I want to see if anyone has attempted to build something like this and any ideas on how to accomplish this build? Thank you for any help for this project.

    12′ Model – Rigid Boats https://www.rigidboats.com/12-ft-model/
     
  2. Mr Efficiency
    Joined: Oct 2010
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    Mr Efficiency Senior Member

    Similar things have been done in alloy, I really can't see the raison d'être, it is an unnecessary complication that doesn't achieve much in practice other than to "look like" a rigid-hulled inflatable. Inflatable tubes at least offer some "give" when coming along side boats, or with swimmers in the water. In any case, a far from simple project to emulate.
     
    Skyak and bajansailor like this.
  3. bajansailor
    Joined: Oct 2007
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    bajansailor Marine Surveyor

    Welcome to the forum SS.
    If stability is your main concern, then I think you would still be better off if you simply made a monohull fibreglass boat a bit wider.
    Even though it will be fatter, it will still be more efficient to row (and hence to power with a small O/B motor) than a RHIB type of boat.

    Re your Rigid Boats link, they have a huge advantage in that they have all the moulds for making the different components of their boats - how would you intend to do this on a 'one off' basis?
    Use fibreglass tubes for the sponsons?
     
  4. SummerSchool
    Joined: Jul 2021
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    Location: Maryland

    SummerSchool Junior Member

    I really don’t have a good idea how to do this. I had two ideas one of using an inflatable dinghy as a mold to make the basic shape. However I am concerned about the flexibility in the for the mold. The other idea I was thinking about was basically building something like a Garvey type hull and building a foam filled tube to be fiberglassed to the rail. I am just in the thinking phase and thought I see if anyone on the board could come up with a good option.
     
  5. Blueknarr
    Joined: Aug 2017
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    Blueknarr Senior Member

    The shape of an inflatable is a good compromise between an efficient hull shape and what is possible with inflation. Why adapt a poor shape unnecessarily? If you're building in FG why not make a better shape that FG allows for?
     
  6. SummerSchool
    Joined: Jul 2021
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    Location: Maryland

    SummerSchool Junior Member

    The idea I like of the inflatable is the ability to step anywhere when loading. Currently I am using a 13ft inflywithva 25 hp engine. I dislike the vulnerability of the tubes.
     
  7. Blueknarr
    Joined: Aug 2017
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    Blueknarr Senior Member

    How wide is that inflatable?
    I bet Stepping over the tubes is a hassle.
     
  8. Blueknarr
    Joined: Aug 2017
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    Blueknarr Senior Member

    It is the width of the waterline not the tube that is providing the stability. Removing the tubes will also allow more interior room.
     
    clmanges likes this.
  9. SummerSchool
    Joined: Jul 2021
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    Location: Maryland

    SummerSchool Junior Member

    The tubes are 18 inches. I tend to step on the tubes getting in and out. I stumbled on these wondering how that would work with a 13 ft Garvey.
     
  10. bajansailor
    Joined: Oct 2007
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    bajansailor Marine Surveyor

    Here is a nice (in my opinion) 15' garvey design -
    15'-9" Jimbo AL - garvey hull with center console-boatdesign https://www.boatdesigns.com/15-9-Jimbo-AL-garvey-hull-with-center-console/products/126/

    You could perhaps put a closed cell foam collar around the gunwhale, or just below, arranged so that it is just above the waterline in the light condition.
    If you then step in to the boat it will try to submerge, and the boat will stiffen up considerably.
    Have a look at the foam collars in the link here -
    Sponsons Air Tubes and Foam Collars | Wing Inflatables https://www.inflatablesolutions.com/sponsons.php#tabr4

    Or maybe the solution is here, with the 'new' Dinghy Dogs -
    https://www.ghboats.com/2017/06/the-new-dinghy-dogs/
     
  11. Barry
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    Barry Senior Member


  12. Saqa
    Joined: Oct 2013
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    Saqa Senior Member

    The inflatable shaped boats have a king though. The Mac 360. I had a 360 attack model with a 25hp. There is no other boat that I would use to throw poppers in close proximity to the ocean rocks and oyster leases in NSW

    It incorrect that the tubes don’t make a difference. The reserve buoyancy in them is significant. Check out the floatation tests on their website

    There is an equivalent model from triumph in US

    A boat made in that shape from fg will not be as tough
     
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