transom core

Discussion in 'Fiberglass and Composite Boat Building' started by garrybull, Jul 3, 2016.

  1. garrybull
    Joined: Nov 2010
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    garrybull Senior Member

    i normally use marine ply in transoms on boats i build.

    im now looking at seacast or nidabond pourable transom.

    does anyone know of any suppliers in the UK?

    all i can find is US or AUS.

    im going to pop in to my grp supplier to see if they can get anything similar or find out what seacast or nidabond is made off to see if they can produce there own.

    im in the middle of negotiations of taking over a small boat manufacturer in the UK which boats they have built in the past have suffered with rotten transoms and ribs/stringers.
     
  2. Stumble
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    Stumble Senior Member

    What's your price sensitivity. My prefered material would be a G-10 core withcosmentic fiberglass overlays. I simply do not trust poured anything to be void free.
     
  3. garrybull
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    garrybull Senior Member

    price wise it cant be too expensive.

    dont want to use ply as i have repaired too many boats with rotten ply even marine ply.

    marine ply nowadays in the UK is expensive and its not much better than a decent wbp hardwood ply.

    whats G-10 core?
     
  4. PAR
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    PAR Yacht Designer/Builder

    Even with UK pricing, a poured, Cossa or G-10 core will be much more costly than plywood.
     
  5. garrybull
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    garrybull Senior Member

    i dont really want to use plywood.

    i know i can bond plywood in absolutely fine but its the people who fit engines that can be the problem if they dont seal the bolt holes properly.

    i could drill bolt holes bigger than they need to be and fill with a paste and then redrill the bolt holes which will seal the ply in the holes if i fitted the engines but its other people.

    most will just drill holes and put a bit of sealant on bolts and thats it.
     
  6. Stumble
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    Stumble Senior Member

    Make the transom out of plywood but the section where the motor will mount use G-10. This way it's no longer necessary to worry about core removal.
     
  7. garrybull
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    garrybull Senior Member

    whats G-10?

    do you have a link to it and can it be bought in the UK?
     
  8. Stumble
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    Stumble Senior Member

  9. SukiSolo
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    SukiSolo Senior Member

    Not much wrong with ply IF it is sealed and the mount holes properly epoxied. This means over drilling say 15/16mm+, filling, and then re drilling for the 12mm mounting bolts for a typical 25Hp or so. Adjust to suit larger mount bolts. Most of the transoms I've repaired have not been treated like this as new, because it takes the time to do it. The benefit is years down the line.

    Agreed, in the UK, marine ply is expensive because we don't make any...;) and of course with the wonderful new trade deals to come it will be so cheap....;)
    Might even be worth laminating a glass transom core especially if flat. Don't need much other than solid flat surface and vacuum pump!
     
  10. garrybull
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    garrybull Senior Member

    thats the way it looks like i'll be doing it now.

    like you say takes time but has to be done.

    im looking at purchasing a few boat moulds with the name soon and im looking to improve them all round and use minimum amount of ply in the builds.

    will be using nidaplast for the decks and bulkheads and probably 50mm foam glassed over for the ribs/stringers.

    i have thought about making a grp panel that can be bonded to the transom.

    never done vacuum bagging so not a got a clue how to do it and hand laying up a 45mm thick panel will take ages and be very heavy.
     
  11. garrybull
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    garrybull Senior Member

    thanks for the link.

    had a quick look and looks like its all made from epoxy resin.

    i use polyester so the 2 wont really work together.

    also look quite pricey.
     
  12. Stumble
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    Stumble Senior Member

    Garry,

    It's common to use it in place of wood core just where the loads are applied. Say a .5mx.5m section. Just cut the plywood out, and bond in the g10 there. You don't need to make the whole transom out of it.
     
  13. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    You can home make up a fairly good version of G-10, with some goo, fabric and a concrete block or two.

    Polyester doesn't stick to epoxy very well, but epoxy sticks to polyester, better than polyester does.
     
  14. garrybull
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    garrybull Senior Member

    i know poly dont stick well to epoxy but the boats i build are built using polyester so epoxy is a no go plus its a lot more expensive than polyester.

    i had a chat with a chap today who can supply me with polyester grp panels to any thickness i want so may look in to that a bit more and if the price is right i may give it a go.
     

  15. SamSam
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    SamSam Senior Member

    I think you can make your own. Looking around and reading about Seacast and Nidabond, it seems they use an unsaturated resin with chopped fiberglass and ceramic microspheres. http://www.eagerplastics.com/filite.htm Seacast uses a BPO catalyst https://www.fibreglassshop.co.nz/products/b-p-o-catalyst?variant=920090565 and I believe these pour in transom systems might use a 'casting' polyester resin and not a regular 'laminating' resin. Seacast says if the temperature of the pour goes to 300f degrees that that is ok and not too hot.

    Here's a discussion from another forum. The 'ondarvr' person posts here also, is very knowledgeable about resins etc. Maybe he could comment about this.

    http://forums.iboats.com/forum/boat...hull-repair/457015-mixing-my-own-transom-pour

    There is also a place called Arjey Industries that makes a transom filler. http://www.arjaytech.com/images/ProductSpotlight_CeramicPourablev3.pdf
    They sell the stuff wholesale by the barrel to boat manufacturers (as opposed to retail sales to individual customers, like Seacast). The only problem is who sells what over there where you are. I'm sure manufacturers there sell similar stuff to boat manufacturers that are located there.
     
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