what to do with the deck.

Discussion in 'Boat Design' started by whitepointer23, Dec 30, 2014.

  1. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    I wouldn't use PVA, as it tends to creep under load, meaning the fasteners are the real attachments, making the PVA a redundant step. Consider polyurethane instead of PVA, though it's typically not cheaper than epoxy, it's more convenient to use.
     
  2. whitepointer23

    whitepointer23 Previous Member

    Is poly the stuff that foams as it drys. I will stick with epoxy if pva is not suitable.
     
  3. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    Polyurethane does foam, but only in unclamped areas, like along seams, ooze out, though holes, etc.

    Be careful with PVA, as epoxy doesn't stick to it well, so wipe up any spills and tooth up the areas well after any clean ups.
     
  4. whitepointer23

    whitepointer23 Previous Member

    No worries par. I just assumed poly foamed up in the joint , didn't realise it was only the outside.
     
  5. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    Poly foams if it's not under pressure in the joint. This means any glue near the edges of a joint may ooze out and foam, unless the joint is well fitted and tight.
     
  6. whitepointer23

    whitepointer23 Previous Member

    I have used the poly glue before but as you said earlier it is cheaper to use epoxy.
     
  7. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    Ounce for ounce costs are cheaper with epoxy.
     
  8. whitepointer23

    whitepointer23 Previous Member

    Can i swing 200 kg off my main boom. The mast and boom look pretty strong . I am thinking of attaching the spinnaker and mainsail halyards to the end of the boom for extra strength and using it to lift the engine out and swing it 90 degrees to put it in my runabout. Am i correct in thinking rigs take a lot more stress than that in strong winds.
     
  9. Steve W
    Joined: Jul 2004
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    Steve W Senior Member

    I have done just that, I used the boom to lift a 2GM yanmar out of a trailer and into the engine bay on a 37ft center cockpit ketch, the boat was out of the water at the time. The mast and standing rigging should be plenty strong. Make sure your halyards are in good condition, not chafed etc.

    Steve.
     
  10. whitepointer23

    whitepointer23 Previous Member

    Excellent. Thanks steve. The halyards are good and all the rigging is quite large diameter.
     
  11. whitepointer23

    whitepointer23 Previous Member

    Another question. I have just made a new companion way sliding hatch. I want to bed the original bronze slides onto the hatch without mechanical fastenings. Will this idea work.
     
  12. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    Without mechanical fastening, a really solid bond will be necessary. Epoxy would be my choice, but I'd consider G-Flex to cover the different expansion characteristics. Bedding suggests fasteners, as it's a sealant, but without fasteners, it's bonding, which means the sealant needs to be stiff. 3M-5200 would do, though not as tough as epoxy, easier to apply (to a degree). Unlike most bedding compounds (like BoatLife caulk, Sikaflex 291 or 292), 3M-5200 isn't nearly as flexible, though does have similar elongation qualities. Sikaflex 292 is a pretty hard product when cured, much better than 291, but still not as hard as 5200.

    If using 3M-5200, tape off the perimeter carefully with a 1/16" clearance around the bond area. Apply sufficient goo to ooze out, once the slides are set, then use an acetone soaked rag to clean up the excess, forming a tiny fillet between the tape and the slides, then peel the tape. This will leave a clean caulk line and make cleanup a lot easier. I've found vinyl or electrical tape works best for this.
     
  13. Steve W
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    Steve W Senior Member

    What he said. G flex has an elongation of around 32% if memory serves which is excellent and is the only west system product that I am enthusiastic about. As Par said, either g flex or 5200 would get the job done. Remember though that neither product likes uv but probably not an issue with your situation.

    Steve.
     
  14. whitepointer23

    whitepointer23 Previous Member

    Thanks paul. Yes epoxy is the plan. I should have said to glue the slides on not bed. If i can epoxy them on i don't have to drill holes through the hatch which i have epoxy sheathed already.
     

  15. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    Scruff the crap out of the pieces, 24 - 36 grit and apply epoxy immediately after.
     
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