blue Dow foam cuddy cabin?

Discussion in 'Boat Design' started by Shinnosuke, Jul 5, 2016.

  1. Shinnosuke
    Joined: Jul 2016
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    Location: Honolulu, HI

    Shinnosuke New Member

    Aloha, I have a late model 13' Whaler that I used for fishing here in Hawaii. It works great but I have taken waves over the front of the boat while trolling and end up with essentially a floating bathtub that's nearly impossible to steer until the bilge catches up. I'm not keen on going through and scooping waves anymore so I want to build a lightweight cuddy cab to enclose the front end of the boat and deflect water and spray. I considered plywood covered with fiberglass and epoxy but its seems too heavy so I debating whether to use some type of foam sandwich construction. The limiting factor here is price and availability of the foam sheets. I would like to use something about 2" thick for stiffness but pvc foamboard/divinycell is beyond my budget so I'm looking at the blue Dow foam I can get at Lowes or some 2" EPS foam that I'm pricing out from a local store now. My question is can I use this blue Dow foam (15psi) either covered with directly with epoxy/fiberglass and/or glue some 1/8" doorskin to the foam with contact cement and glass that or am I wasting my time and should just go with 1/4" or 3/8" ply/glass? The trapezoidal shaped dimensions are roughly 7' long by 3' at the bow and 5' at the steering wheel end. Mahalo for any info.
     
  2. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    You can use the blue foam from the big box store, but the strength and stiffness of the spray dodger will be dependant on the 'glass sheathing you'll apply to both sides (the only way foam cored, sandwich methods work). Buy the time you add it all up, you pay more in goo, fabrics and foam, than 1/4" plywood and few 1x2's. Weight wise, if you make the foam as stiff and strong as the plywood version, they'll weigh about the same. This means it's all about cost and pain in the butt factor. So, if you can laminate well and efficiently, foam core is the way to go. On the other hand, plywood and some sringers is about as easy a weekend project as a basic wood craft might stumble on, so pick you poison, based on budget and skill sets.
     
  3. Shinnosuke
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    Shinnosuke New Member

    Thanks for the advice and here's one more question: if I'm using the 1/4" ply, what laminate schedule do you recommend? A couple of layers of 6oz cloth or so both sides would be sufficient or...? BTW, clicked on your tips and tricks link, very helpful, answered a bunch of other questions, thank you!
     
  4. SukiSolo
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    SukiSolo Senior Member

    The main advantage of the foam option is you can hotwire cut it to really curved shapes - but it takes quite a bit to sand smooth and well....;) before glassing...and a fair bit after that too.

    Don't forget if you do the ply option, and I probably would myself, to use 9mm for the flat bit you need to stand on for the painter or anchor cleat. You can get away with 6mm (1/4") but put enough decent height stringers underneath it. Certainly 6mm would easily do for the rest.
     
  5. FAST FRED
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    FAST FRED Senior Member

    The blue foam usually has to be epoxy coated first to keep polly resin from dissolving it .

    Thin ply with sringers or reinforcement glued on the back will be cheap, and last a good while.
     
  6. tom28571
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    tom28571 Senior Member

    I agree with the consensus that ply is the most reasonable option although a pipe/canvas cuddy would work also and be foldable for bow access. As to glass sheathing, I don't think its needed. Structure design is far more important than sheathing. If you are expecting to actually move about on top of the cuddy, the structure gets even more important.

    Main problem anyway is the design of a Whaler which induces lots of spray over the bow due to its bow shape. A much over hyped boat in my opinion.
     
  7. Shinnosuke
    Joined: Jul 2016
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    Shinnosuke New Member

    Thank you for all the advice. I will probably not walk on it at all, maybe just grab on to the sides from time to time so its main purpose is to deflect water if I should plow through a wave. I got the idea from some boats around here as well as some whalers up in the Santa Barbara area (see pics).
     

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  8. Shinnosuke
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    Location: Honolulu, HI

    Shinnosuke New Member

    Here are a few more pics...
     

    Attached Files:

  9. Wavewacker
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    Wavewacker Senior Member

    You might consider corrugated plastic sheets over a wood frame, easy to bend and well braced it's tough stuff. Might get it free from a bar changing signs or a beer distributor and just paint it. :)
     
  10. SukiSolo
    Joined: Dec 2012
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    SukiSolo Senior Member

    The trick with EPS is you can cover it with Latex adhesive if you want to use it as a form for a Polyester layup. Not greayt for leaving as a structural core that way though.
     

  11. mickyryan
    Joined: Apr 2016
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    mickyryan Junior Member

    I did my roof with tri ply underlayment with a sheet of r factor yellow with the faced sides with foil from big box store , I used poly floor underlayment glue because its basically just like pl premium as in polyurethane glue and waterproof then I used 1 " lattice for sides to cover foam and wrapped with 6" oz then topped with matt under I braced middle with a 2x4 because I will be hollowing out 2x4 for wireing then capping with a piece of triply and trim to hide wires, used 1 1x2 cross ways to add strength it works I can walk all over it , also did nonskid finish
     
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