Aft bulkhead repair/replacement

[Avenger]

It looks like it's my turn in the barrel here. We're pulling things out and trying to figure out how Hatteras put this whole mess together, and how to replace the rotted sections of the aft bulkhead with a minimal amount of carnage.

Does anybody have any idea what holds this cabinet on port side in? We've removed every fastener we can find. Every piece of trim, molding, etc. and it's still rock solid. It does not appear to be tabbed to anything. Series 1 36C. Any suggestions would be appreciated before I have to take a crowbar to it.

[omecojh]

On our 42C, we replaced the bulkhead on the port side below the window from the side to the door and down to the floor
. We used an saw and wood chisel to remove the plywood from the exterior fiberglass (very thin).
We used Coosa board behind the exterior fiberglass and fiberglass to build back the thickness.
It was a messy project but will not rot again.

[Dazed338]

Damn, glad I haven't run into anything that bad YET on my 1967. Fingers crossed as I get into some areas I haven't seen yet.

[Avenger]

On our 42C, we replaced the bulkhead on the port side below the window from the side to the door and down to the floor
. We used an saw and wood chisel to remove the plywood from the exterior fiberglass (very thin).
We used Coosa board behind the exterior fiberglass and fiberglass to build back the thickness.
It was a messy project but will not rot again.

Thanks for the input. I take that to mean that you did the work from the inside? Also, I've never worked with Coosa before. Can I just lap that to the plywood that is sound? I'm hoping to avoid a complete replacement.

A lot of my bulkhead has been hacked up, I think when the boat was repowered. And the window leaked causing a lot of rot as well. The tackle center hid a lot of patches and problems.

[rsmith]

I feel your pain

Thanks for the input. I take that to mean that you did the work from the inside? Also, I've never worked with Coosa before. Can I just lap that to the plywood that is sound? I'm hoping to avoid a complete replacement.

A lot of my bulkhead has been hacked up, I think when the boat was repowered. And the window leaked causing a lot of rot as well. The tackle center hid a lot of patches and problems.

[Cricket]

Yes you can attach the Coosa to the plywood. I would make sure there is some thickened epoxy in the joint between the wood and the Coosa, just make sure to use 1 or 2 layers (2 overlapped would be better) of 1200/1208 or 1700/1708 biax cloth on both sides to make sure everything stays strong/stable.

[Avenger]

When you say cloth on both sides I'm @$$uming you mean on the outer surfaces. I've found a few things where Hatteras bonded wood to fiberglass structure and it looks like they used a piece of mat to hold resin in between the surfaces.

While I'm asking dumb questions, does anybody know how the door frame is held in? I can't see any evidence of fasteners or seams. The wood actually looks like it wraps around the bulkhead and is mostly held captive by the fit of the pieces. I assume this is another one where adhesives are also involved.

[Cricket]

Epoxy is the best resin (glue) for attaching "fiberglass cloth" to wood.
Vinylester resin would be next followed by polyester resin for glassing to wood.
Just remember you can put epoxy on the other 2 but can't put the vinyl or poly on top of epoxy.
You do not have to have "mat" if you're using epoxy, only the "cloth"
So, 1208 and 1708 Biax cloth has a layer of "mat".
1200 and 1700 Biax cloth does not have a layer of 'mat".
The Coosa gets it's strength from being sandwiched between the outside layers of cloth.

We do most of our repairs in epoxy, mainly because we're better with epoxy, and we do not like smelling the other resins.

Any suggestions Rusty???

[rustybucket]

Epoxy is the best resin (glue) for attaching "fiberglass cloth" to wood.
Vinylester resin would be next followed by polyester resin for glassing to wood.
Just remember you can put epoxy on the other 2 but can't put the vinyl or poly on top of epoxy.
You do not have to have "mat" if you're using epoxy, only the "cloth"
So, 1208 and 1708 Biax cloth has a layer of "mat".
1200 and 1700 Biax cloth does not have a layer of 'mat".
The Coosa gets it's strength from being sandwiched between the outside layers of cloth.

We do most of our repairs in epoxy, mainly because we're better with epoxy, and we do not like smelling the other resins.

Any suggestions Rusty???

I was wondering when I'd get invited to this party!!

I think I'm pretty well sold on vinyl ester for all projects now big and small. I used to prefer epoxy on the smaller projects but I'm so used to the vinyl ester now it's easier than epoxy to me.

For bonding ply to coosa. I'd thicken some resin with cotton flock and some chop strand. Dump it on and spread it out with a notched grout trowel. Then I'd screw them together with many sheetrock screws. After the cure (a couple hours) I'd pull all the screws out and continue with my job glassing the outside. You will have to destroy either/both pieces to get them apart.

Coosa is awesome, just protect yourself when cutting/grinding it. It's some super itchy stuff, normal fiberglass doesn't even bother me anymore, I don't even notice it, but coosa in me and I can't even sleep at night. When cutting/grinding wear a tyvec with a hood, respirator, ski goggles and rubber gloves.

I use a normal skill saw blade to cut it, we use normal router bits to round over the edges and a fast wood blade seems to do well with it in a jigsaw. Bring extra jigsaw blades, if you cut much you will go through plenty.

Each boat is different, but if I were into the project far enough to be laying glass on the bulkhead I would FOR SURE come out the other side with a mezzanine or at least much better storage than stock.

Speaking of fiberglass, hopefully the weather this weekend is going to be warm enough to allow me to finish glassing my mezzanine!

Just for reference here is my Mezz thread, has lots of details/images that may be helpful to others.

https://www.samsmarine.com/forums/sh...Winter-Project

[omecojh]

To bond the Coosa board to the exterior fiberglass we used a putty recommended by our supplier.

I can't recall the name of the putty, but apparently is used by boat builders to bond the Coosa board between two layers of fiberglass.

I think you have 20 minutes after mixing before curing.