Spots of Fiberglass Showing below the Waterline

[landonshaw]

I'm on the hard sanding the bottom of my boat. There are small spots that I am down to fiberglass, others are to a filler. I was told by another boat next to me, who just splashed, that it is a good idea to cover the spots with West System 2 part epoxy before you apply a barrier coat.
Has anyone else done this procedure?

[Cheechako]

If you are down to filler and/or glass on the whole boat by all means put the resin on there! I prefer the 2 part real resin to any barrier coat, but many on this forum prefer the barrier coat. All I know is I fixed 3 bad blister boats in my life with real resin, the boats were dried out but not peeled. I know each of them lasted at least 3 years with no return of blister.. beyond that I dont know.

[landonshaw]

I am looking at using 2 part resin, then lightly sanding with 80 grit, then a couple coats of barrier paint. The entire boat is not down to fiberglass, just small areas. I would use a small brush to apply.
Yes, I have 17 blisters that I have ground out and am letting them dry and will preform a similar process on them, except will use a small amount of colloidal silicon.
Currently the plan, but as always things change.
Thanks Dave s/v Aloisius

[minaret]

Not necessary. The only reason to do this is that the bare glass patches are likely to be full of pinholes which will be a problem when you start coating. If you are roll applying 2000e, they would likely fill by coat four and not be an issue. But, to be sure and in case you are using a different product, apply a tight fill of 3M Premium Filler (vinylester) to fill the pinholes and sand it out before applying your barrier coat. This process is much much faster done this way. Make sure to trowel in two directions to achieve fill on the pinholes.

[minaret]

Originally Posted by landonshaw

I am looking at using 2 part resin, then lightly sanding with 80 grit, then a couple coats of barrier paint. The entire boat is not down to fiberglass, just small areas. I would use a small brush to apply.
Yes, I have 17 blisters that I have ground out and am letting them dry and will preform a similar process on them, except will use a small amount of colloidal silicon.
Currently the plan, but as always things change.
Thanks Dave s/v Aloisius

Glass your blister divots high and then grind them fair instead of just filling them. They'll come back if you just epoxy fill.

[landonshaw]

Minaret, are you saying that it might be easier and still achieve good results to use 3M Premium Filler rather than 2 part epoxy on areas that are not blisters but where the fiber glass is showing? Thanks

[Cotemar]

landonshaw,

I would follow what minaret said to do, as he does this kind of stuff for a living and does it well.

Here is a PDF to help you understand the process.

[minaret]

Originally Posted by landonshaw

Minaret, are you saying that it might be easier and still achieve good results to use 3M Premium Filler rather than 2 part epoxy on areas that are not blisters but where the fiber glass is showing? Thanks

Yes I am.

[minaret]

Originally Posted by Cotemar

landonshaw,

I would follow what minaret said to do, as he does this kind of stuff for a living and does it well.

Here is a PDF to help you understand the process.

Not a bad recipe for the amateur. Not how I do it, but good advice nevertheless.

[landonshaw]

Minaret, neither marine store here in Grenada have the 3m PremiumFiller in stock so I have put 2 coats of the 2 part west system epoxy over May bad areas. I will be putting a third this afternoon. I sand with 80 grit paper between. Is it necessary to then put a few coats of barrier paint over this before covering wit anti foulant? Thanks Dave s/v Aloisius

[landonshaw]

Additionally, as in Cotemar's article, it sounds like after the blister is repaired, and in my case bad areas, then all you need to do is paint with bottom paint.

But is this optimum or should you still use a barrier coat before painting wit antifouling paint?

[minaret]

Originally Posted by landonshaw

Additionally, as in Cotemar's article, it sounds like after the blister is repaired, and in my case bad areas, then all you need to do is paint with bottom paint.

But is this optimum or should you still use a barrier coat before painting wit antifouling paint?

I always use barrier coat. We used to do barrier coats in straight epoxy in the old days. Seen to many failures. I'd barrier coat the whole bottom if you have it down to bare gel now. Numerous advantages, such as the ability to chemical bond your bottom paint to the barrier coat, which insures an excellent bond and no flaking down the road. I prefer 2000, also for numerous reasons. Easy work, even for the layman.


You don't need to sand between coats of WEST. Just catch the bond window. You should be able to apply multiple coats in a day.

[minaret]

Originally Posted by landonshaw

Minaret, neither marine store here in Grenada have the 3m PremiumFiller in stock so I have put 2 coats of the 2 part west system epoxy over May bad areas. I will be putting a third this afternoon. I sand with 80 grit paper between. Is it necessary to then put a few coats of barrier paint over this before covering wit anti foulant? Thanks Dave s/v Aloisius

When you applied epoxy to the bare glass, did you note pinholes? Did they fill? When using epoxy for this, I usually make a thin filler with 407 and screed it on tight with a two way pass to fill the pinholes. Fills much better, sands easier.

[landonshaw]

I did not notice any pin holes, some fiber and mostly white filler in areas. I will sand the epoxy with 80 grit and barrier coat it along with the blister that I am repairing. Thanks