new dinghy mold

Discussion in 'Boat Design' started by dan catalyst, Aug 5, 2013.

  1. dan catalyst
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    dan catalyst Junior Member

    I just picked up this original 8 foot dinghy mold. its a classic tender design , to be used rowing/sailing tender with a gaff/cat rig . Ill also be testing several outboards from 4hp two stroke to 8hp four stroke. last pick is a completed hull,first is the mold itself. the scantlings will be either 24oz woven in the middle of 1.5 csm or 2.0 csm w/ 18 oz woven in the middle , overlaps down the keel and a little core material in the transom,all poly resin. Ill also be adding a keel locker, but might pop a few row boats out for testing first.:) [​IMG]
     
  2. dan catalyst
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    dan catalyst Junior Member

    completed hull [​IMG]
     
  3. messabout
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    messabout Senior Member

    Sweet looking little boat. Eight horsepower will be useless overkill. It is not likely to go any faster with an eight than a four.

    The little hooker seems a bit narrow and round bottomed for sailing. If you rig it for sail it had best be a modest one. Not much bigger than an Opti rig. Gaff cat rig will be salty looking but not nearly as simple as a sprit rig. The Gaff rig will be more expensive too. Halyards and blocks and hoops and jaws and all that.
     
  4. dan catalyst
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    dan catalyst Junior Member

    good point,simple is key. i was looking at the snark sails @ 45 sq' that should be about all she needs. the boat is eight foot, four foot of beam.
     
  5. messabout
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    messabout Senior Member

    Should be a fairly easy hand layup except at the skeg. I could like it if no chopper gun was ever allowed any closer to the build than 100 yards away. If you are going to rig it for sail you will need a dagger board or centerboard trunk that will complicate the layup a little bit.

    Figure out the interior layout for thwarts, mast bridge, and trunk position before you get too far along. From the looks of her she is going to give meaning to the term; tender. (pun intended)
     
  6. dan catalyst
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    dan catalyst Junior Member

    Yes, i agree on the no chopper gun, ever.im going to pop one row boat out b4 i add the dagger board trunk. im ready to lay one out just as soon as i get an idea of what to use lamination wise.it came with rolls of glass, one looks like 8-10 oz woven roving, another is 1.5 csm and a few heavy 8'' tapes aprox 24oz+. how would you laminate this out? i was thinking gelcoat ,two layers of 10 oz roving then the heavy tape on the the keel and sides then 1.5 csm over that. will i need csm on the gelcoat as the first laminate,or is it ok to start with roving ? and your best guess 2-3 gallons of resin,or more? thanks so much for your input! im standing here with my roller in hand, wondering what to do next,lol. thanks again
     
  7. dan catalyst
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    dan catalyst Junior Member

    [​IMG] [​IMG] not my layup, just the hull that was in the mold.
     
  8. messabout
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    messabout Senior Member

    I am a poor adviser for layup schedules. Way back in the dark ages I did build a bunch of FRP canoes. Times, materials, and methods have changed.

    For such a small boat, I would not think that roving should go near the external surface. Maybe a sequence of gel coat, angel hair matt, woven cloth, then roving. All the while endeavoring to avoid resin richness but not being stingy with it.

    More knowledgeable FRP guys could stick their oars in here to give you more modern and knowledgeable advice.

    If 'twas me I might entertain the idea of plugging the skeg cavity and adding the externally mounted skeg after the main body has been done. That narrow hole in the mold is sure to be problematic. Not impossible but a pain nonetheless.
     
  9. dan catalyst
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    dan catalyst Junior Member

    I was thinking the same thing the last couple of days. it does have that 24 oz+ tape all the way down the skeg though. that might even be heavier, but in any case i found a barrel roller that fits down there perfectly.if its a issue then ill fair it out just enough to work when i add my daggerboard locker.
    I called fgci today and they are going to come up with a layup scedule for me tomorrow.its looking like 2-3 laminates of 1708 or 1808 layed in poly resin.I might try and get some foam core strips into the sides if i can too. I have allot to learn,I dont expect the first one to be perfect!
     
  10. Gilbert
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    Gilbert Senior Member

    There is no reason to have even a two horsepower engine on this boat except that you may not be able to find a smaller one.
     
  11. rwatson
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    rwatson Senior Member

    If you can get some hi-density foam for the sides of the board case, either in strips or in panels, you would end up with a much stiffer construction too, once you put same thinner layers of FG on the outside.

    Its incredible how a bit of a core can make FG so much 'stronger'
     
  12. waikikin
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    waikikin Senior Member



    Some great advice there, gelcoat is gunna be tough to get nice down there too, a timber add on skeg might help dress it up along with some lami timber gunnels.
    Jeff
     
  13. SamSam
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    SamSam Senior Member

    That skeg doesn't look particularly difficult to laminate. I think it would be more nuisance cutting, fitting and attaching a wooden one and then having to deal with it maintenance wise. It would probably only take 10-15 minutes to laminate it and then it's there and won't ever rot or leak, but would probably take a few hours to make from wood, install and then have to keep an eye on it.

    It would be easy enough to try though, temporarily filling the cavity with some sheet foam and then fairing it out with clay or adhesive tape.
     
  14. michael pierzga
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    michael pierzga Senior Member

    The keel forms a handy bilge for collecting water and keeping your feet dry.

    A nice bilge pump setup is when you insall a whale type footpump in the foot rest.

    Easy to pump and row.
     

  15. dan catalyst
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    dan catalyst Junior Member

    do you guys think that 1.5 mat and 18 oz roving or cloth, followed by another 1.5 mat,run overlaps down the skeg might do it? two or three gallons of poly resin? epoxy is too expesive, ill have to get some practice w/ hand lay up b4 im willing to invest that much.im trying to keep it cheap and simple at first thanks for the replys!
     
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