Ruined maststep and repairing gelcoat

[dgr]

I had my mast unstepped this last weekend. Due to the age of the vessel and the aluminum to aluminum contact betwee the mast step and the mast, the step (What was left of it) came along for the ride.

Now I have to build a new mast step and repair the cabin roof. I've cut back to clean wood plywood on the roof and have installed a fiberglass plate with studs for the new mast step. I'm pretty confident in my ability to build a new fiberglass step and get it located where I need it to be. While I could leave the ugliness underneath the new mast plate for the next owner, I would not do that. I am going to properly grind back and glass the seam between the old deck and the new fiberglass plate, so will need to repair the gelcoat or paint.

I really don't want to paint. The whole boat needs to be painted and I just don't have the time or funds to do so.

Here's what I know:

Gelcoat on epoxy is an iffy proposition. It might stick and it might just pop off with a hard stare.

Polyester on epoxy produces a less tenacious secondary bond than is desired.

Gelcoat on polyester/vinylester resin is the right way to go for getting the best chance of adhesion.

I fair with 3M premium marine filler. It's vinylester based.

So, would the procedure with the best chance of success be to finish the rough in with epoxy, fair with 3M and gelcoat that? Should I overlay the final fairing with a coat of straight vinylester resin and go from there?

Thanks for any advice (other than paint it )

[sailingdog]

Actually, there's a nice paper on gelcoat adhesion to epoxy resin on the West Systems website. It actually adheres fairly well, as has been my experience, and the real key to getting gelcoat to stick to epoxy resin is preparation more than anything else.

Originally Posted by dgr

I had my mast unstepped this last weekend. Due to the age of the vessel and the aluminum to aluminum contact betwee the mast step and the mast, the step (What was left of it) came along for the ride.

Now I have to build a new mast step and repair the cabin roof. I've cut back to clean wood plywood on the roof and have installed a fiberglass plate with studs for the new mast step. I'm pretty confident in my ability to build a new fiberglass step and get it located where I need it to be. While I could leave the ugliness underneath the new mast plate for the next owner, I would not do that. I am going to properly grind back and glass the seam between the old deck and the new fiberglass plate, so will need to repair the gelcoat or paint.

I really don't want to paint. The whole boat needs to be painted and I just don't have the time or funds to do so.

Here's what I know:

Gelcoat on epoxy is an iffy proposition. It might stick and it might just pop off with a hard stare.

Polyester on epoxy produces a less tenacious secondary bond than is desired.

Gelcoat on polyester/vinylester resin is the right way to go for getting the best chance of adhesion.

I fair with 3M premium marine filler. It's vinylester based.

So, would the procedure with the best chance of success be to finish the rough in with epoxy, fair with 3M and gelcoat that? Should I overlay the final fairing with a coat of straight vinylester resin and go from there?

Thanks for any advice (other than paint it )

[jarcher]

Just wondering, is this a common problem when unstepping a mast from an older boat? Mine is getting pulled this week and if there is a risk of this happening, I may just skip it and climb up to do the work...

[dgr]

j,
I have a total experience with one. But it seems like anywhere you have aluminum to aluminum contact, you are going to have corrosion. Mine is a tight slip fit so ....

BUT, it was obvious that it wasn't coming off. They were able to lift the boat an inch or more with the mast crane. I could have said forget it and hooked everything back up with no damage to the boat.

[sailingdog]

Actually, aluminum to anything is usually a problem, and you really should use some sort of grease or anti-seize compound to prevent the aluminum from reacting.

[HPLou]

After having to replace a deteriored aluminum mast step, I made a thin plastic/vinyl gasket to keep a separation between the aluminum mast and the new aluminum mast step. It definitely took care of the problem.

[sailingfool]

You can cut a gasket out of a used plastic 1 gallon milk bottle.