'86 Tournament 190 - Fuel Access Cover re-core job

[bfrank]

I know this has been discussed a lot but I wanted to post up for someone that might still researching or debating doing the work.

A little history: I bought the boat and most of the deck is solid but this cover was very soft. I had visions of me or one of my family members (big boys) ending up standing on the fuel tank. So I wanted to get it fixed.

Out with the old...



Almost there...


I bought 1 sheet of 3/4" pressure treated plywood. It was less than 1/2 the price of marine grade and my plan was to completely enclose the wood in epoxy so I figured I was safe.

We cut it to fit but there was a bow in the center that we needed to get leveled out. So we cut it into 5 separate pieces and used a router to cut down the sharp edges.


We mixed up the 2 part epoxy and painted the bottom of the ply and put a thick coat onto the cover. Then set the wood in place and stacked about 250 lbs on top and let it sit overnight.


We cut up some glass and mixed it into the epoxy to create what I'm told is sometimes referred to as cat sh!t. That was then stuffed down into the cracks and allowed to cure.


Prepping the glass mat.


Glass mat weted in.



Getting close now...


After a little sanding, buffing and wax and we're ready for installation.


It was a fun project. If I can find the time I would like to do the forward cover with the same treatment.

 

[gw204]

Careful using regular PT wood. Resin can have trouble adhering to it from what I've read.

I've heard of the term "kitty hair". I think it refers to single short strands of glass that can be added to resin. "Cat sh*t" is a new one for me... :lol:

 

[JeffN]

It doesn't look like you removed the last "ply" layer of old the plywood and just placed your new sheet over it. If that is true may I ask why? I am doing a similar project and have to remove that last layer this weekend. I did not think it would make a very stong base to bond to so I am going to remove it. Perhaps I am about to find out why you left it there. :hmm

 

[gw204]

Definitely grind off all the wood that may be left stuck on there.

 

[bfrank]

It doesn't look like you removed the last "ply" layer of old the plywood and just placed your new sheet over it. If that is true may I ask why? I am doing a similar project and have to remove that last layer this weekend. I did not think it would make a very stong base to bond to so I am going to remove it. Perhaps I am about to find out why you left it there. :hmm

That last very very thin layer of wood was sanded with a belt sander. Our thought was the more I chewed on that thin layer the more I risked damaging he fiberglass cover. The thought that this fiberglass cover is irreplaceable kept me being extremely careful.

Careful using regular PT wood. Resin can have trouble adhering to it from what I've read.

I've heard of the term "kitty hair". I think it refers to single short strands of glass that can be added to resin. "Cat sh*t" is a new one for me... :lol:

"kitty hair" is what I read on the Internet and "Cat sh*t" is what my uncle's friends who work on this stuff regularly call it.

The wood is in and never coming out (hopefully) so we'll see how it works. I know it's not much of a test but so far so good.

 

[gw204]

The tiny bit of thickness lost by grinding away any plywood remnants can easily be replaced by putting down a layer of mat prior to dropping on the new core. This ensures you get the best bond between the skin and the old core. When I do the main panel in my 227 here shortly, my plan is to grind down to clean glass, put down a layer of either 3/4 or 1-1/2 oz mat and then lay my 3/4" marine ply core after coating the surface of the ply with unthickened resin and then applying more thickened resin w/ a notched trowel. Once that cures, I'll come back and glass over everything.

 

[JeffN]

bfrank - I'll let you know how it goes. I am going to use the bar to try and get a bit more ply off before I start sanding. Some of my pieces already came off down to the skin so I'll see just how hard a job it will be. If I can I would like to start fresh.

Curious that we have three of these projects going at once.

 

[bhemi]

Pressure treated vs Marine

The big difference between marine and any regular plywood is that marine uses a waterproof glue to hold the laminates together. I would worry about pressure treated plywood not having enough permeability as it has already been soaked in another treatment.

An alternative recommended to me by a builders supply that stocks specialty woods is "Baltic Birch". It has more laminates per thickness than regular plywood and is resistant to water caused delamination. The strength comes from the glass and the epoxy not the plywood. If you look at the original it looks like a checkerboard of small 4" squares. The cat sh*t you refer to is consistency other sites say "peanut butter" . Kitty hair is the loose mat as opposed to woven glass.

When I did it four years ago I ground it down to bare glass and wiped it down with acetone. I bedded the plywood pieces in epoxy thicked up to "peant butter" consistency. I soaked the plyood in straight epoxy and put two layers of mat over that. I cleaned it up and painted it on the underside after. You could gelcoat but who is going to see it?

 

[bfrank]

Curious that we have three of these projects going at once.

From my reading this is a pretty common problem.

The big difference between marine and any regular plywood is that marine uses a waterproof glue to hold the laminates together. I would worry about pressure treated plywood not having enough permeability as it has already been soaked in another treatment.

I think the pt ply took the epoxy ok. I guess we'll see.

 

[gw204]

From my reading this is a pretty common problem.

Yep, very common and IMO the main cause is poor construction of the hatch covers. Grady ran the core all the way to the edges of the panel and this caused the screws to pentrate the core and created an easy path for water to get in and rot to start.

When I rebuild my hatches, I stop the core about 1.5" short of the edge of hatch, bevel the edges at 45 degrees so the glass will conform nicely and run a few extra strips of 1708 or 1808 in the channel formed to build thickness/strength. This isolates the core from any possible water intrusion.

 

[JeffN]

Well I removed all the old ply today, a bit of a job but it is all gone now. I'm glad i removed it as some of the ply was still stuck on very well but a lot of it not so well. I am also building a new panel for the rear of the cockpit and worked on that most of today. Once I get that off the bench I can begin glassing the deck panel. I am going to try to get the core material fitted tomorrow.

 

[JeffN]

From my reading this is a pretty common problem.

Yeah I know it is. Just move coverage on the topic than I can rememeber, which is a good thing IMHO. I like to see people keeping the old boats going.

I agree with 204 in that the problem was the original construction ie the screws going through the core material. I have a couple of ideas about how to remidy the issue just not sure which one I will use. On the subject of the original core material the pieces in bfranks deck are positivly huge compared to the pieces in mine. I did hold up for almost thirty years but it does make me wonder what other gems are in there.

 

[bhemi]

A good point was made about running the plywood to the edge. I drilled my holes oversized and then filled with thickened epoxy and re-drilled the proper size. That way the screws are only in contact with epoxy not wood. This should be standard practice when putting any fitting through a cored deck.

 

[bfrank]

I was trying to figure out how to monitor the condition of the wood. Specifically watching how the epoxy handles the PT ply. So I cut a couple pieces to replace the boards up under the front seats. I gave them a nice coating all the way around. Now I can keep and eye on them to see how they are aging.

 

[dgaines]

Great job all you guys. Thanks for the pictures Brian. What weight fiberglass mat did you use? Yes I am facing this task also after finishing up most of my running todo list.

Dick Gaines
86 Tournament 19 "Sugar"
88 Yamaha 130

 

[gw204]

I used 2 layers of 1708. It is 3/4 oz match stiched to a layer of 17 oz cloth/roven. I believe the official name is "stitchmat".

Very little strength in mat alone.

 

[bfrank]

Great job all you guys. Thanks for the pictures Brian. What weight fiberglass mat did you use? Yes I am facing this task also after finishing up most of my running todo list.

The mat was sourced for me but IIRC it's 24 oz mat. It's some heavy duty stuff which is why we only did one layer.

I'll have more pics coming I took a look and my forward cover is also fubar so I ripped into that last weekend. I'm hoping to have it glassed this weekend but we'll see.