One Off GRP Swim Step- Advise needed

Discussion in 'Fiberglass and Composite Boat Building' started by pescaloco, Sep 18, 2014.

  1. pescaloco
    Joined: Feb 2006
    Posts: 301
    Likes: 10, Points: 18, Legacy Rep: 81
    Location: so. california

    pescaloco Senior Member

    Hey Guys

    I need to make a GRP swim step aprox. dimension 96 in X 32 in

    I don't know if it is possible to make a cheap mold, designed for one time use.
    The step will need to fit a convex transom profile and should have soft radius corners and have vent slats in flat face of the step.

    How would you go about building this ? A mold or make a panel and cut everything out and fair as needed

    Any advise you can offer would be appreciated

    Thank you
     
  2. garrybull
    Joined: Nov 2010
    Posts: 508
    Likes: 16, Points: 18, Legacy Rep: 143
    Location: portsmouth england

    garrybull Senior Member

    fairly easy to make a one off temporary mould.

    i would use melamine board and cut it to the shape of the transom and then put a lip around the shape you want on the underside and then use plasticine with a filleting tool to get nice radius'd edges and then wax it and gel it up.

    build it up to thickness with csm and combi mat and then add either plywood or nidaplast to reinforce it and keep it flat and glass over.

    once done trim the edges to desired thickness.

    you'll then need to find a way of attaching it to the boat.

    hope that sounded easy enough.
     
  3. gonzo
    Joined: Aug 2002
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    Location: Milwaukee, WI

    gonzo Senior Member

    Something that size will need to be cored. Otherwise, it will be very heavy. You could build it out of 1/8" plywood with a foam core and then fiberglass over. It will be much easier to get good radiuses with a router.
     
  4. pescaloco
    Joined: Feb 2006
    Posts: 301
    Likes: 10, Points: 18, Legacy Rep: 81
    Location: so. california

    pescaloco Senior Member

    Thanks guys

    The whole putting a lip around the platform is what is throwing me off
    the inside edge has a big crown in it and the outer corners (not the edges) have to have a decent radius.
    What type of material can I use to make a mold for the vertical lip and make a nice radiused corner.

    Thanks
     
  5. jorgepease
    Joined: Feb 2012
    Posts: 1,614
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    Location: Florida

    jorgepease Senior Member

    I agree, you don't need a mold for this, just use foam core panels and cut and build up as needed. Fairing should be easy.
     
  6. wet feet
    Joined: Nov 2004
    Posts: 495
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    Location: East Anglia,England

    wet feet Senior Member

    Whichever way you decide to approach the job remember not to make the top flat.It needs to be capable of shedding water and if it is flat and level you will find a puddle developing sooner or later.This will then become green and slimy and not a nice thing to have around.

    Either approach to making the part will work.For me it would be quite important to avoid the need to laminate overhead and I might feel inclined to go with the temporary mould.
     

  7. pescaloco
    Joined: Feb 2006
    Posts: 301
    Likes: 10, Points: 18, Legacy Rep: 81
    Location: so. california

    pescaloco Senior Member

    Thanks guys
    Any one know of a good material that could be used to form the lip in the mold and is bendable and will form smooth radius and a large concave arc
     
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