Tri hull restoration project

[I'D RATHER B FISHN]

Re: Tri hull restoration project

This is a diagram of how I plan on glassing the transom. Its a side view of looking at the transom.

IRBF

 

[I'D RATHER B FISHN]

Re: Tri hull restoration project

oops, in your reply you say not to use CSM with epoxy, why is that???

 

[Woodonglass]

Re: Tri hull restoration project

CSM requires polyester resin to disolve the fibers (styrene) in the mat and make it all a one part mixture. Epoxy does not have styrene and thus will not dissolve the fibers in the mat and thus weakens the mix. I would like to see pics up under the splashwell and the inner skin of the stern where the wood is being attached. It must be strong in the corners and you must be able to get the corners all filled in solid. For me, I just don't think this plan of attack is going to work. You are talking about the most critical part of the boat, the one that must be the strongest, and you have made it the weakest. To get it back to where it was, I would cut out the inner skin and tab the entire transom to the hull on the inside and the outside and then run muliple layers of Biax over the entire transom both inside and outside wrapping it onto the sides and botoom of the hull. Without this, I fear failure. That's just my humble opinion. OOPS will be back to agree or disagree I'm sure.

 

[I'D RATHER B FISHN]

Re: Tri hull restoration project

Woodonglass I sure don't want failure to occur. I will post those pics you've requested. I guess I made a mistake cutting out the outer skin, but I want to restore this boat and I want to be able to use it.

You think if I cut the inner skin out and layering new glass(something heavy like the biaxial, CSM or both?) on the inside of the transom turning the corners extending onto the gunwales of the boat for a foot or so? In addition to this add glass (biaxial, CSM or both) to the outside of transom turning the corners and extending a foot or so?

If I take this approach how do I sand the glass that has extending beyond the corners of the boat (inside & outside)? I mean the build up especially on the outside when I turn the corner will be bulkier then the original wall/glass of the boat. I'm sure I will have to knock it down???


IRBF

 

[Woodonglass]

Re: Tri hull restoration project

If she were my boat this is what I'd do. I'd use the transom as a backer. I'd cover the wood with plastic set it in place and then clamp the outer skin piece to it. Then sand and feather the edges as shown in the diagram below. You will then use CSM and Resin and 1708 Biaxial cloth to fill the depression and patch the outerskin back to the edges you left. It will not stick to the plastic. In about an hour you can remove the clamps and the wood transom piece. You will then need to probably cut the splashwell out just in front of the gunwales along with the inner skin of the transom. Once you have full access to the outer skin from the Inside you will lay two full layers of CSM a layer of 1708 Biax another Layer of CSM and another layer of 1708 over the entire Outer skin on the inside and wrap it around the sides of the hull on the inside. They will be sanded down to good glass before hand. This will make the outer skin as strong as it ever was. You will then proceed with a normal transom install by using PB to glue and clamp it onto the outer skin. Then fillet the edges and lay two layers of CSM, a layer of 1708 and your back in business. Hope that all makes sense. If not PM me and we can go over it in more detail.


Click the pic to enlarge

 

[I'D RATHER B FISHN]

Re: Tri hull restoration project

Woodonglass, I think I follow you, but my only problem is the new wood is set in the transom flange with epoxy and some glass. I think I would further tear the transom up trying to remove is. I don't know if I will be able to access the outer skin from the inside if I can't remove the wood. Is there any way of taking the flange that I left and tying into it to get the strength back? Here are the pics of the inner skin and splashwell. Thanks for your help.

IRBF.

 

[I'D RATHER B FISHN]

Re: Tri hull restoration project

 

[I'D RATHER B FISHN]

Re: Tri hull restoration project

 

[I'D RATHER B FISHN]

Re: Tri hull restoration project

Another question. Since epoxy can't be used with biaxial that has CSM backing (because of the styrene), I purchased polyester resin, unwaxed. I was wondering if I put a layer of CSM using the poly (unwaxed) and a layer of the biaxial w/ CSM backing using the poly (unwaxed) can I finish it of with a layer of cloth and epoxy to ensure a hard outer layer? My fear is I don't have the wax in the poly and I won't get a cured finish, it will be tacky to the touch. I have read on another thread on iboats that applying epoxy over poly resin is ok, but I want to make sure it is ok to put epoxy over unwaxed polyester?

Thanks,
IRBF.

 

[oops!]

Re: Tri hull restoration project

yes it is but you are way over thinking it.

even unwaxed poly resin twill be an adiquate water barrier for many years.

you also mentioned a layup schedule.....

csm.....1708.....and some kind of cloth...this will not work.....(with poly).

however if you lay the csm and the 1708....let cure....or semi cure....and then lay the roving with epoxy you will be fine.

BUT.....it seems to me that you are proceeding from an incorrect point of view.

this is the idea that poly is not water proof, and epoxy is.....while on the molecular level this is correct....on a practical level for what we are doing......poly will last you plenty long enough. waxed or unwaxed.

if you wish to add the epoxy, it is your boat, you can do what you wish.

 

[I'D RATHER B FISHN]

Re: Tri hull restoration project

oops,
If I do go all poly on the exterior of the transom does the last layer have to be poly with wax in it? My fear is after reading some forums that unwaxed poly will always remain tacky which leaves a surface that is not sandable or paintable. Also from a strength standpoint, I have read that poly is not as strong (not as strong as epoxy) when applying new fiberglass over existing fiberglass. What is your opinion?

IRBF

 

[I'D RATHER B FISHN]

Re: Tri hull restoration project

Ok, for covering the outer skin you guys have suggested this 1708 biaxial. I was wondering if this is absolutely necessary? I will order it if it is since I can't find the stuff at any of the local boat places here, not sure why, but no one has it. Would it not be strong enough to use polyester resin only (no epoxy) with 2 layers of CSM and 1 layer of biaxial? Also the put a finish layer of cloth (using poly) for finishing? I hope these questions don't seem redundant but I just want to make sure I understand the process of layering the glass. Thanks,

IRBF.

 

[oops!]

Re: Tri hull restoration project

sorry ...my puter was sick for a couple of days.

ok.....back to the poly epoxy thing.....use one or the other.

i suggest poly.....it is plenty strong enough to do what you need.

first off....grind off the gellcoat on the entire transom...make sure its as smooth as you can. fill the gap between the cut with structural filler peanut butter.....the recipe is in my sig ...use the index. (oops super dooper structural peanut butter)

as well ...grind off the 6 inches of gellcoat all around the transom....on the sides and on the hull.

then clean with acetone...use 2 layers of csm.....i 1708....1 csm....1 1708....1 csm...and a 6 oz finishing veil.
make sure this wraps around to the out dies of the side and under the boat.
(yep....you really screwed the pooch when you cut the transom off bud that is why we say before you start...read read read )

you are worried about the bump between the sides and bottom and the transition to the new glass.
this is going to require a lot of fairing. possibly a few more layers of glass to go longer up the hull and sides.

after its back to flat.....(dont leave a hump on the plaining surface) then you can re gellcoat this area.

for the inner hull.......after the transom is glass in from the out side.......then you are back at squair one...

grind off the inner glass.....and use the same layup schedule for the inside......wrap the glass around the inside edges...
then you can do your stringers and deck.