86 Sunsport Transom Repair

[csuggs]

So when I had my floor and stringers replaced a few years ago, we ignored the fact that I had some rot in the transom. There are 3 wooden blocks located in the transom where the 3 swim platform mounts are located. The one in the center is good, but the two outboard blocks are rotten. I've tried using CPES from the Rot Dr. But there just isn't enough wood there to make a difference. So I'm thinking about making the repair this winter. If I remove the fuel tank (again), then I think I can gain enough access to cut out the fiberglass and remaining wood from the inside with a cutoff wheel. Then if I grind and clean the surface, I should be able to replace with new wood and re-glass the inside - right?

Any thoughts on this, ideas . . .

What materials do I need to adhere the blocks to the transom and then glass over?

[Okie Boarder]

I would think you could access everything you need that way. If you remove the gas tank and rear seat it opens up quite a bit. I think yours is the same or similar to mine, right? I found this pic from my restoration project...looks like you can get to everything. I'd say just bed them in place with a thickened epoxy, then glass over them. Coat the wood in CPES prior to installation.

[csuggs]

My ski locker doesn't come out like yours, but I'll probably end up cutting it out. Otherwise they look the same.

[michael hunter]

You are on the right track with your repair. Make sure you use a marine grade plywood . I like the bedding them in with epoxy and covering them with glass idea. You could also use 1/4'' aluminum plates over the finished blocks just for anal over kill. Instead of a grinder you can use a vibrating blade tool like a Fein multimaster it will cut the glass between the hull and transom without making such a big mess.

[Supra_Comp]

On my '85 Comp, we did exactly what Michael is talking about above. We put aluminum plates on both sides and used 3M 5100...a lot of it. The transoms are very weak in these boats, notice a massive improvement with the plates.

http://i678.photobucket.com/albums/vv142/GT40_Sally/IMG_00000156_zpsca3d1242.jpg

[csuggs]

You are on the right track with your repair. Make sure you use a marine grade plywood . I like the bedding them in with epoxy and covering them with glass idea. You could also use 1/4'' aluminum plates over the finished blocks just for anal over kill. Instead of a grinder you can use a vibrating blade tool like a Fein multimaster it will cut the glass between the hull and transom without making such a big mess.

Specifically, what materials would you recommend as far as epoxy and glass. . . I've done a lot of things, but never any fiberglass work.

[Jetlink]

Specifically, what materials would you recommend as far as epoxy and glass. . . I've done a lot of things, but never any fiberglass work.

http://www.uscomposites.com/

Give these guys a call and explain what you are doing and they should be able to point you in the right direction. Might have to email them a picture or three but this is where I would start.

[Okie Boarder]

Probably a couple layers of the 1708 biaxial and epoxy resin would work good. I used 2-3 layers of that stuff on my stringers and it worked really well.

[ngavchris]

Daniel had the same issue with his boat before he had the stringers done. He had Donny do just what your talking about. He definitely did not cut the ski locker out.
This was how he first met Donny. Later on they did the full stringer replacement.

[csuggs]

Thanks. I wish I lived closer to Donny Bennett. There is an outfit in Cincinnati that could do it, but I think I'm going to go ahead and tackle this one. My ski locker is different. I'll post pics when I get started.


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[Salty87]

You can do it. Practice glassing a scrap piece of wood first so you don't create add'l grinding if it goes bad. It's not hard but a little practice goes a long way. Preparation (having glass cut to size and everything nearby and ready to go)...timing (once the resin starts to set it doesn't wait for anybody)....technique (glass properly wetted with no air gaps underneath)...again, nothing really complicated but coordinating it all is important.

[wotan2525]

For the small amount of material you're talking about -- I'd just use some starboard and skip the CPES. Never have to worry about rot again.

[csuggs]

Where do I get starboard?


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[wotan2525]

Where do I get starboard?


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http://www.westmarine.com/west-marine--poly-sheets-building-material--P004_135_001_009

[Salty87]

Starboard is an interesting idea although you can't glass or glue it to the hull. With either that or glassed wood you'd still want aluminum backing plates to spread the load. Only issue with starboard I can think of is sealing it. I don't think 4200 or anything else will stick to it well and since it's not glued to the hull water could leak between starboard and hull. Maybe I'm missing something.

[wotan2525]

Starboard is an interesting idea although you can't glass or glue it to the hull. With either that or glassed wood you'd still want aluminum backing plates to spread the load. Only issue with starboard I can think of is sealing it. I don't think 4200 or anything else will stick to it well and since it's not glued to the hull water could leak between starboard and hull. Maybe I'm missing something.

This is news to me and you might want to check with starboard. I thought you could use it interchangeably with wood and I haven't run into much that 4200 or 5200 wouldn't seal. Salty87 may know more than me, though!

[Salty87]

It's great when you only need to cut or screw but chemical fastening is a problem. From Tap Plastics' website:
* Because King StarBoard sheet products are designed to resist water and grime,
they cannot be painted and the use of adhesives is not recommended. If gluing is
absolutely necessary, products such as 3M’s Scotch-Weld DP-8005 and Lord
Corporation’s 7540-AB have been used with some success. Special welding rods,
designed for use with polymer sheets, are also available.
http://www.tapplastics.com/uploads/pdf/WorkingwithKingStarBoard.pdf

[csuggs]

Sounds like maybe I should stick with the wood. It made nearly 30 years the first go-round so if I use wood with CPS, etc. - maybe it will last another 30 - longer than me!


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[leetudor]

What about Coosa Composite Board?

[Brosh]

This. I did this exact repair the same way Michael is explaining last spring and it worked great, i understand the aluminum is probably overkill, but i am a big guy (6'3" , 250lbs) so i don't want that thing flexing and cracking hopefully the extra bracing keeps the water out for good this time. i would recommend a small fiberglass roller to help make sure you get all the bubbles out, and make sure you are wearing a respirator and goggles (not just safety glasses) when you cut it out that dust gets everywhere.

[csuggs]

http://tapatalk.imageshack.com/v2/15/03/14/4cb5006a1a26928479b935e4437adb8b.jpghttp://tapatalk.imageshack.com/v2/15/03/14/1b0b07df2285dbfde085e724849c84e0.jpghttp://tapatalk.imageshack.com/v2/15/03/14/816e0f06001fdfe2a766f7f551a0b4df.jpg

I got the old material cut out. The orbital saw worked really well.


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[Okie Boarder]

Looks like you're off to a great start!

[csuggs]

So I just ordered materials from US Composites - 1708 Biax cloth and epoxy 3:1 resin

[csuggs]

I finally got around to making this repair. Coated the back side of oak plywood with 3:1 epoxy, then after letting it absorb for about an hour, I bedded the wood in with 3:1 and cabosil thickener. Tomorrow I will mix up more thick epoxy and fillet the edges before applying the cloth one day next week. http://images.tapatalk-cdn.com/15/04/18/e580ab9ea314ec6d03e956cd56e91127.jpghttp://images.tapatalk-cdn.com/15/04/18/c08972d8846acddc7be30274d967d8fa.jpghttp://images.tapatalk-cdn.com/15/04/18/f9777f4117f006ecc378db750a37a9ed.jpg


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[Okie Boarder]

Looking good Clint.

[lively]

I like seeing those support plates !!! good stuff bud !