Re-Building hand built Cross 28', what materials??

Discussion in 'Multihulls' started by Oode, Feb 10, 2015.

  1. Oode
    Joined: Feb 2015
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    Oode New Member

    I am the current "caretaker" of a Cross 28' trimaran, built in the late 70s. The deck is in rough shape and I need to replace some of the glass over the wood. The original builder said he used West Systems and some sort of alternative cloth, Perimean?? or similar, that I can find no reference to.
    Any info on the best way to rehab this would be much appreciated...
    not going for 'good as new', just needs to be serviceable and maintainable.
    Let me know your thoughts...
    Thanks!!!
     
  2. cavalier mk2
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    cavalier mk2 Senior Member

    Lots of things would work. I haven't heard of Perimean. Dynel is easy to use, especially on more complicated shapes and has better abrasion resistance than glass. Check out the fabrics at Defender and Jamestown. If you use fiberglass 6 oz is the maximum to consider. For resin I'd stick with WEST. For UV protection, use a dark gray or black primer coat to preserve the epoxy.
     
  3. redreuben
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    redreuben redreuben

  4. PAR
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    PAR Yacht Designer/Builder

    Welcome to the forum.

    I'm fairly sure Perimean is a reinforced cotton fabric, which would make it a ***** to fair, if used on a boat.

    Xynole is the hands down choice, with Dynel a distant, but still much more effective second, compared to 'glass cloth.

    Usually, when the sheathing "lets go" you'll have significant rot under it, as it traps moisture against the unprotected plywood.

    There are lots (thousands) of previous threads about this type of repair process. Use the search tool and have a few hours of light reading.
     
  5. cavalier mk2
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    cavalier mk2 Senior Member

    Changing my last post to be more diplomatic. Xynole is great in the right place but uses a lot more resin than Dynel. The fibers wick and absorb the equivalent to 10 oz glass cloth. This adds weight and cost (resin isn't cheap) to the boat in a area you don't need the advantages Xynole can offer but do need to save weight. Dynel is thin and drapes well over corners etc...compared to other weaves though I imagine it will all seem a bit sticky until you've had practice with different things. I'd put the 6 oz glass at # 2 for the deck as it will save money and weight over the Xynole and still have good protection used with epoxy. Don't try to use anything other than epoxy for this project, polyester won't stick to anything well.
     
  6. cavalier mk2
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    cavalier mk2 Senior Member

    A pointer with Dynel is to just use enough resin on the first coat to wet it out on the first coat. If you keep trying to fill the weave it floats off the wood. It will look rough after it dries but readily fills with the next couple coats.
     
  7. PAR
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    PAR Yacht Designer/Builder

    Dynel and Xynole use about the same amount of goo to wet out, though both use a lot more than regular 'glass fabrics of the same weight. Dynel uses about 2.5 to 3 times as much resin and Xynole uses 3 to 3.5 times as much resin to wet out as 'glass cloth of the same weight.

    Given your desires, I agree with Cavalier in that regular cloth will probably be just fine, saving some bother and resin. As to the weight of Dynel and Xynole, well if it's a canoe or kayak, yeah, you need to worry about it, as every ounce counts, but most boats just will not be that affected by the additional resin weight, particularly a 28 footer. The difference between 1 pound or 3 pounds of resin, just isn't worth getting upset about.
     
  8. Oode
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    Oode New Member

    I appreciate the input!
    Most the areas that need repair are on the flat part of the topsides... I will probably make thin cut through the exiting laminate and scrape off the old where I can, and grind the rest.. There are a few soft spots where the water has trapped, but thankfully the original builder used good materials and many places the wood is holding up quite well.
    Since this boat long ago gave up the fight to be truly light, sounds like good old 6 oz glass will be the call. One layer or two??
    For resin, I'm using Raka right now, have had good experience with it in the past... not quite west, but close... and for the quantities I'm using and the expectations on the boat, it seems to fit the bill... now I just have to figure out how to feather the new and old together so it doesn't look too awful... and get some anti skid that goes on easy....
    It will be spend most of the near future on the Neuse River/Pamlico Sound....
     

  9. cavalier mk2
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    cavalier mk2 Senior Member

    Cut out the bad spots and scarf in new, this is really easy. Watch out for stringers and frames, if the edges are in a open area you can put in butt blocks of the same thickness decking after beveling the edges with plane and grinder to give more support and easier nailing.
    It is pretty easy to feather edges in glass, I like a disk sander but they take some practice and need to be kept moving to avoid digging in. A little filler can smooth the rest.
    One layer of 6oz is plenty, if you want to use 2 make them 4 oz. The Raka resin will be fine. There are antiskids like Kiwi grip that are high hide but they weigh a lot. I horrify the yachties and use latex but then we actually go sailing, plus it is easy while our own renovations continue.

    One of the flush cutting tools from Harbor Freight are really handy for things, finishing out for a circular saw etc, cutting down to a stringer, corners and all. Make sure you are careful about cut depth on everything to avoid more work.
     
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