O.K. you f/g experts, I need some help.

[Billybob]

As some of you may recall, I ripped a piece of skin off the bottom of my 23 last fall.It's about 16" wide by 20 feet long right down to the roving.It's finally warmed up enough to get to this and I'll take pics once I get it off the trailer.
My question is, what do I order to repair this?
First, what weight mat do I need?
Poly or epoxy? The guys at the boat yard insist poly because that is what they used originally. I'm kinda leaning toward epoxy because it's a big area and the epoxy gives you more time before it kicks. But, I don't want any incompatability issues.
Between layers, do I need to layup within a certain time period with either system - or will I need to sand and wipe between?
Your favorite source to order from would help too.
Thanks,
Bill

[Bigshrimpin]

Epoxy has the strongest bonding properties out of all the resins and it's totally water resistant (unlike polyester). Polyester is great for laying up inside a mold, but repairs below the water line should be done with epoxy.

[FELLOW-SHIP]

I totally agree with using epoxy. BUT you will have to Paint the bottom instead of re gel coating it. You should buy those little booklets from West Marine regarding repair work from The West System. I would also want to roll the boat over on it’s side to help gravity get the epoxy and glass to lay down properly. On a job like this vacuum bagging might be a good way to go. As for which glass to use for me I would rather use a few layers of glass instead of one thick woven rovin layer. There is a boat down here in the shop with this same type problem. Good luck and remember lots of Beer.
FellowShip [img]/images/graemlins/wink.gif[/img]

[warthog5]

Actually there are 2 epoxy resign's that can be gellcoated over. Ringleader did it to the stem of his boat using WEST System. I saw the boat 3yrs latter and it's flawless. I have never done it.

The other epoxy resign is made by System 3.
http://www.systemthree.com/p_sb_112.asp

Recommended Uses:
It was especially formulated for use in building and repairing sail and surfboards over polystyrene cores. It can also be used for coating and laminating. SB-112 is unique in that polyester resins and gel coats may be bonded to it without the use of "tie-coats". We recommend that polyester be bonded onto freshly sanded SB-112 epoxy within 48 hours of cure.

[Billybob]

Thanks guys - Epoxy it is.I won't be gelcoating anyway, barrier coat and bottom paint.I plan on laying it on it's side as much as I can and I will be doing multiple layers.
I'll try to get some pics.

Bill

[rcnight]

I agree with everyone - epoxy is the only way. There are tons of sources. Do a google and I'm sure you'll fine one close to you. A trick I learned on my last boat build will save you alot of finishing time and you could probably get away with leaving the boat rightside up. If you don't vacum bag, this may work. Find a thin flexable board (luan ply or masonite) and make it non-stick. Layup your patch work in reverse (finish layer down first)on the board and secure it to the work area. You might need to use small tap screws or wedge it up in place. The idea is the non-stick surface of the board makes a smoother finish, thus less finish sanding and holds the patch in place. Good luck!

[Ed]

Billybob-

Polyester resin will work fine (since your boat was originally made with it)but epoxy is known to have better secondary bonding characteristics so if you don't mind shelling out some extra $$$$, go with the epoxy. As far as glass is concerned, I would order 1.5oz mat and 1808 biaxial...which is much easier to wet out than the 24oz woven roven that your boat was made with. I would start out with a piece of 1.5 oz mat that is smaller than repair area and than go with a slighlty larger piece of 1808 and then keep repeating the process of using gradually bigger pieces until damaged area is covered.

[abl1111]

A few questions:

As always, I humbly defer to your experiences, but there were two things mentioned that I thought were " no-no's":

o using micro balloons for water proof/underwater applications ( better to use cabosil ?)

o using mat with epoxy - I thought mat was not good w/ epoxy, and cloth was preferred ?

I just need this clarified for my info.... Thx.

[Scott]

I wasn't going to get involved in this one with poly vs epoxy but
Honestly I would talk with a few more professionals, in the yards and suppliers, and get their advice first ... I dont think this is something anyone would want to do twice !!!

I've not heard about the glass spheres or microballons not being able to be used U/W ....Thats a common fairing material that can be mixed with other agents to make suitable fairing compounds... Cabosil is more "structural" and a bitch to fair. Again with talk of a barrier coat you are good to go.

Mat... I have always always been told that fiberglass mat, which is what I would use as the first layer against the damage area, Chemically and Physically bonds with the poly based resins. There is a chemical reaction between the mat and poly that creates chemical interlinking and bonding …. I think I would definitely want that in your situation. That first layer is going to hold everything together. The understanding I have is that this is not true with epoxy. Depending on how much you need to build up the suggestion is a layer of mat then structural glass( like the 1808) mat then glass. (You can also buy the glass with the mat already stitched in to the 1808 )

Look into Vinylesters ( higher grade polys and even Iso resin) as they are more water resistant ....plus if your doing a barrier coat your protecting it anyway. We all know that they are compatible with your hull...so there is no guessing

Joe Merton would be a good individual to call ... www.mertons.com he's great to deal with and in Springfield, Ma. and better yet is a SeaCraft admirer.

[Billybob]

Wow, thanks for all the advice, knew I could count on ya's.
What I think I know is that chopped mat is held together with some type of binder which reacts with the poly but is hard to wet out with epoxy.But they make a stitched mat just for epoxy that doesn't have the binder.
So, I was thinking of using that and cloth in layers.I am a little concerned about the whole mess sagging on me while I wait for it to set.I have used plastic sheet before as a release film so I'll have to figure out what I can do to support it.I guess I'll go with the thicker epoxy too, that should help some. Vacuum bagging is beyond me.
I also think you need apply your subsequent layers during the time between initial gel stage and full cure or you'll be sanding good between layers.
So, I'll keep you posted.
It's a really bizarre thing, I've never seen this happen to a boat before.