which fiberglass to use?

[mnessman]

I am wondering what type of fiberglass do I need to use when replacing the stringers and deck for my boat. I have seen some people using the chopped mat and others using cloth. Is one better than the other? I am replacing all of the stringers along with the transom and the deck for my boat and I want it done right so that the boat will last along time. I am planning on using the CPES epoxy to soak all of the wood in prior to glassing them in, I will also be using the marine grade plywood for both the transom and the deck. The stringers I plan on using kiln dried 2x wood. Any thoughts and help are always apprciated.

 

[redfury]

Re: which fiberglass to use?

You can save yourself the expense of the CPES and use regular poly resin to coat the stringers with...you can just reduce it with acetone to get it to penetrate. If you are encapsulating the stringers with fiberglass so that water cannot get to the wood, then you really don't need to protect the wood that mightily.

As far as glassing everything in goes, you can do your initial wrap with CSM ( chopped strand mat ). Lightweight stuff like 3/4oz will conform to the curve over the top of the stringer as you can tear it slightly to make it work, or you can use a light cloth that will conform to the top ( cap ) of the stringers. After the stringers are completely sealed with a layer or even two of the light stuff, then you'd want to use a heavier grade fiberglass to shore them up. A product called 1708 is used commonly. It's a grade of glass that uses mat as a backing to stick to the layer underneath, and uses the top layer for the strength. It's stitched together, not woven-which gives it great strength. Not horribly expensive either.

As far as the transom goes, CSM works fine as the wood is the strength there, as well as the deck. You just want to make sure you have enough layers that it isn't easily punctured. I plan to use the huge roll of 3/4 oz CSM I picked up and use 2 layers on the bottom of the deck, and probably 4 layers on the top...possibly more since I've got so much to use.

There are a lot of specialty types of fiberglass out there. check out www.uscomposites.com website, it'll help you decide what is best for you.

 

[mnessman]

Re: which fiberglass to use?

Yes I know that I could different products, but I am looking at keeping the boat for quite some time and I dont want to have to worry about wood rot for as long as I own the boat. I had also thought about using cypress for the stringers since they naturally resist wood rot, but obtaining sinker cypress cost a pretty penny and isnt the easiest to locate.

 

[oops!]

Re: which fiberglass to use?

here bud....this will help on the glass

http://forums.iboats.com/showthread.php?t=272983

 

[mnessman]

Re: which fiberglass to use?

Thanks oops I had read this post once and it had some great information. I even printed out your reply so that I can have something to go by. Thanks again for the help....

 

[ondarvr]

Re: which fiberglass to use?

It's commonly thought that epoxy will stop the wood from rotting, it won't, if it gets wet it will rot. What prevents rot is keeping the wood dry and that's all about encapsulation, not penetration. If you do a good job with either product the boat will last far longer than you need it to. What needs to be done is pay a great deal of attention to any seams, edges, screw holes, trim and anything that will penetrate the laminate There's nothing wrong with using epoxy and it will do some things better than polyester, just don't think that because you used epoxy you have nothing to worry about.

When using epoxy there's no need for mat, so any of the knitted or woven fabrics can be used.

You never did say what size or type of boat this is.

 

[mnessman]

Re: which fiberglass to use?

Its a 17' Lamar Runabout. Since I first started the planning stage I had palnned on using the CPES epoxy and marine grade plywood and all sorts of things that turned out to be fairly expensive. I have since then rethought my project out, I still want a good job but I dont want to spend an arm and a leg to do it. I am now planning on using the poly resin and not getting the marine grade wood but in using pressure treated or other good wood. I was planning on doing the seacast for the transom but now i am just going to replace the wood and refiberglass. The only delima that I have right now is determining how much glass that I will be needing. The boat is 17', 60" beam its has 5 stringers that are of the 2X wood (I am not exactly sure of the heights that I need yet). I had planned on getting 25yards of the 1708 glass for the stringers and the hull. Then getting 25 yards of the 1.5 csm for the deck and the transom. Let me know if this sounds about right or if it too much or if I need more. Thanks for the help....