Stitch and Glue Limitations

Discussion in 'Boatbuilding' started by Conor64, Dec 7, 2020.

  1. Conor64
    Joined: Dec 2020
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    Location: Australia

    Conor64 New Member

    Hey Guys,
    Planning out a stitch and glue build for a 12 foot dinghy.

    I am curious as to the limitations of a Stitch and Glue build.
    Sorry if some of the questions seem basic i just need some help getting my head around the possibilities of the project.

    I see a lot of smaller builds online that look like they are just being wrapped in one layer of six-ounce cloth, top and bottom, they look very lightweight and seem to all have smaller outboards. They don't seem to be getting flogged...

    The boat i would like to make is going to have at least a 30hp on it and it will be a max of 12 foot in length. Heavily inspired by the Greenough 13 footers and the hawkins 10 and 12 foot boats. I want to be able to go hard on it in relatively rough, short chop without worrying to much about breaking the thing.

    So...
    can these things be beefed up a bit?

    I live on an island it would be my go to boat on days when the weather is looking okay, so it will be used a lot more than normal..
    It could be a stupid question i just need some help, any is appreciated.

    Thanks
    Conor
     
  2. wet feet
    Joined: Nov 2004
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    wet feet Senior Member

    I doubt that you will get to many recommendations as nobody will want to encourage a new builder to run the risk of drowning himself.I also think it is entirely achievable for an experienced builder to build a rugged S&G hull.It may need an amount of additional framing to resist speed in a chop and mustn't gain too much weight in the process.The fastest way to get afloat just has to be buying an existing hull.
     
  3. bajansailor
    Joined: Oct 2007
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    bajansailor Marine Surveyor

    Welcome to the Forum Conor.

    Is this a boat that you have designed yourself?
    If it is, can you post a sketch or two showing what it looks like?
    If it is not, have you bought a existing plan?

    I can find some info on 17' and 21' Greenough designs on line, but nothing on a 13' version - do you have any photos of existing boats for reference?
    Greenough 17 — Anderson Custom Boats https://www.andersoncustomboats.com/greenough17
     
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  4. DCockey
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    DCockey Senior Member

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  5. fallguy
    Joined: Dec 2016
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    fallguy Senior Member

    Jacques Mertens has a few nice designs and his FS14 is probably setup for that hp.

    I think he may allow a 10% reduction as well. Ask him.

    boatbuildercentral.com
     
  6. cracked_ribs
    Joined: Nov 2018
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    cracked_ribs Junior Member

    Typically I'd say upping the power on most stitch and glue designs in that range just means another layer of glass but it does depend on the design, for sure. A lot of 12 footers wouldn't take a 30, I'd say; there's a tendency for S&G designs to be more low-power efficiency-focused and 30 horses is a lot of jam for a boat that size.

    And if that's your minimum I think you're almost into needing a pretty specific design to start with. I can't recall seeing a 40 on a 12 footer, ever. If I was starting with a design like the FS12, which IMO is a pretty typical 12 footer, and someone handed me a 30 horse motor and asked me to get it built to withstand the bottom loading, I'd practically double everything AND change the stringers and bulkheads. It's a big change. 30+HP would send a 12' S&G into orbit.
     
  7. DCockey
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    DCockey Senior Member

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  8. fallguy
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    fallguy Senior Member

    Not really valid; an extra layer of glass is really ambiguous. Xtra 6 oz or xtra 1708@25oz?

    Sorry, but the big question is the transom. And whether the hull is really designed for those orbits as you said at the end.
     
  9. cracked_ribs
    Joined: Nov 2018
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    cracked_ribs Junior Member

    In most cases another layer of whatever glass was spec'd for the build - if it was originally designed for 1/4" ply and 12oz biax, another layer of 12oz biax. If it was designed for 3/8" and 10oz weave, another layer of weave.

    I'm not specifying a particular design here, I'm talking about a rough approximation of what typically gets done to handle increased bottom loading.

    Is that valid enough for you?
     
  10. DCockey
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    DCockey Senior Member

    Increasing ply thickness by an amount which adds equal weight to another layer of glass may increase stiffnes and bottom strength more.
     
  11. Conor64
    Joined: Dec 2020
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    Location: Australia

    Conor64 New Member

    Thanks So much everybody for all the info.
    lots of valid points.

    i will post a few pics and links as to what I am trying to build,

    Custom Hawkins 10 skiff https://www.bdoutdoors.com/forums/threads/custom-hawkins-10-skiff.569729/
    so this little boat here is basically exactly what I would like to build but 2 foot longer.

    [​IMG]
    this is the 12 foot hawkins to get a rough idea..

    Anderson boates in the states builds pretty much exactly what I'm after however its on the other side of the planet. I cant find anything remotely similar here in aus that's not a tinny so I'm going to have to give it a go building it myself... its been my dream boat for a long time, i have met a great bloke online who has helped me out with a lot of info regarding the history of these hulls. im in no rush, want to do it properly

    im basically going to have to design the hull myself going of some rough dims and pictures....


    don't worry mate im a pretty good swimmer. Got to start somewhere, would love the help.


    Thanks mate,

    I havent designed anything as of yet, have worked on boats a lot in the past, but never designed anything.
    Look forward to learning, i figured this build is a pretty good place to start.
    I don't mind purchasing some plans as a guide however i would like it if i designed and built the whole thing (with the help of others of course).



    sounds good mate, look forward to going into orbit! aha. but i do actually want it to go fast... i have checked out the FS12, i just want something with a deeper v. all of the S&G builds look like they are relatively flat.

    where i live has a lot of backwash from wind/ wake and it can be a terrible little stretch of water. my dream has always been to try and design something small 12, foot or under, that will eat up a little bit of chop. from what i can find. the hawkins 12 footers look like its pretty much what i am after in a little boat.
     

  12. cracked_ribs
    Joined: Nov 2018
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    cracked_ribs Junior Member

    Yeah, that shallow V is very common on small S&G designs. I'm struggling to think of a deep V on anything that small.

    But then if you already intend to design it yourself, that's less of an obstacle.

    At any rate it's definitely possible to design a stitch and glue boat to handle that load... what you may have to look out for is the V making her a bit tender. I have a big deep V glass tank and it's not a problem when the boat is eight feet wide and the cockpit is thirty inches deep with rails all around. But a 5*12 skiff... I'd be putting some significant thought into fairly large reverse chines.

    Or, if you really like doing unique stuff, water ballast.
     
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