Fiberglass question for final stages repair project..

[Hou-Chap]

I am in the process of repairing the deck on my 19' chaparral. I have removed the deck. I have also removed the foam on both sides of the center stringer I will be repairing prior to relaying the deck. The stringer has a wood core. I plan on cutting out the bad section (about 4' length), and splicing a new encapsulated piece in with an epoxy adhesive. I then plan on applying some mat and resin to the whole stringer. Does that sound like an acceptable form of repair for the stringer?? If not, any advice and/or suggestions would be appreciated. Once the stringer is repaired I plan on relaying the deck and repouring the flotation foam. I plan on using 3/8" marine plywood treated to poly. resin all around. I have heard conflicting advice on what size mat/cloth to use, and how much (how many layers?). I originally had planned to lay a layer of 1.5 oz mat, then a layer of woven roving, then a layer of 1.5oz. mat, then a final layer of light cloth. Does that sound like enough? or overkill? Is there someone out there that knows what to cover the deck with, and how much? I know that epoxy resin would be ideal to use on the deck too, but could save a sizeable amount of money by going with poly. (Unless it is extremely unacceptable to use poly resin on a deck). Thank you for any help you can give. I can't wait to wrap this deck project up...almost done!

[Eric Sponberg]

For a 19' boat, the fiberglass layup you suggest might be enough--1.5 oz mat, 24 oz woven roving, 1.5 oz. mat, and 10 oz cloth. Polyester resin will do OK, although, epoxy generally is better--sticks to the original laminate and the wood better.

You might be able to tell what the original lay-up was in two ways: First, grind back a largish area, feathering out the thickness in a long slope or taper. The different layers will become apparent, and you'll see the weave pattern in each layer--mat-roving-mat etc. They are pretty easily distinquishable. You can do this on the deck and on the stringer. For the repair, duplicate the layup. For deck finishing, you'll have to refill and refair with hi-build putty and then prime and paint.

The second method is to cut a small piece of the laminate out and burn it with a torch. The piece should be about 2" diameter. Burn the laminate until all the black soot is gone, even between the layers. What is left is the separate layers of the original fiberglass layup, and they will easily peel away from each other. Again, duplicate this layup.

Eric

[Hou-Chap]

Eric,

Thanks for the reply. I have decided to go with the Epoxy resin again (I keep going back and forth). The cost savings associated with going with the poly is tempting, but I don't want to have to do this again in a year or too. This brings up two questions now. I have heard that you shoudln't use epoxy resin with fiberglass mat due to it not being able to break down a binding?? If anyone could clarify the best glass to use with epoxy resin I would be greatful. Will I have any problems when it comes time to paint the deck, as far as compatibilty issues with epoxy resin and most deck paints?? Thanks again for the response. I plan on finishing up this project this weekend (weather permitting), so any advice before hand is always comforting. Thankx!

[Eric Sponberg]

Yes, most mat is bound together with a binder that dissolves in styrene, the liquifier in all polyester and vinylester resins. I makes up about 45% of the resin. There is a product called stitchmat which is stitched together and does not have any binder. This is compatible with epoxy resin. If you use epoxy on regular binded mat, the binder will form a milky mix in the resin and turn it milky white. This will undoubtedly affect the strength of the resin. Woven roving and glass cloth do not have any binder in them.

As far as painting is concerned, there is no incompatability problem. You should follow the manufacturers instructions for fairing and priming. For Awlgrip polyurethane, they have a complete line of products for filling and fairing that you can apply over the laminate, sand down and fair out, and then prime and paint.

Eric