Grinded tons of blisters. Now what?

[ferrailleur]

She's my Catalina 27 after soda blasting which revealed tons of blisters. Almost finished grinding!!!!
I was thinking of filling the depressions with West System 105/205 plus colloidal 406.
It's too much work at this point.
Should I instead apply two coats of some Interlux epoxy barrier. The first coat would be thicken so it would fill my grinded depressions?
Your thoughts. Thanks.

[Don C L]

Personally I'd fill them first, it won't take as long as you think. Just trowel the epoxy putty on and smooth it off quick, like icing on a cake. Know anybody who does cakes who might like to help? Sand it smooth then the 2 coats of epoxy barrier. Helped a friend with his boat that way. It seemed to come out well. As I recall we used the Interlux epoxy filler.

[Allied39]

Yup,
put in the time and effort, it's not that hard. Builds character

I would also recommend adding a little micro spheres or better still micro balloons.....give the mix just a little flex. The other thing it does is makes it a little easier to sand.

Not too much though, as you are after a pretty strong mix.

Epoxy with just silica has no flex, and is brittle. I never, never ever use straight epoxy/silica mix.

I have over the years gone through hundreds of gallons of epoxy, so I do know what I am talking about.

Nope, no interest in arguing with those that know better.....I dont care.

Hope this helps.

[smj]

Originally Posted by Don C L

Personally I'd fill them first, it won't take as long as you think. Just trowel the epoxy putty on and smooth it off quick, like icing on a cake. Know anybody who does cakes who might like to help? Sand it smooth then the 2 coats of epoxy barrier. Helped a friend with his boat that way. It seemed to come out well. As I recall we used the Interlux epoxy filler.

Petite has a high build epoxy barrier coat and you may be able to get away with 2-3 coats, but I’m pretty sure Interlux recommends 5 coats to be effective.

[Fore and Aft]

ferrailleur how about letting her dry out a bit before you fill all those blisters? Some people do not like moisture meters but I certainly like to use them in situations like this. The first reading gives you a starting place and then a week later get it read again and there should be a difference. When I was a boat builder and I was in a rush I would use a heat gun on individual ground out blisters to help dry them. (You have way to many) When I used the heat gun you would always see some moisture rise to the surface and evaporate.
Cheers

[Don C L]

You know, I was reading about the yellow goo coming out of the blisters being acidic and a catalyst for the reaction that generated the blister. We used baking soda wash on the blisters and they bubbled up quite a bit and then we washed them out. I THINK they dried out much better that way since the acidic liquid did not seem to dry out too well. I've never heard of anyone else applying a neutralizing bath, so we might be crazy.

[ferrailleur]

Originally Posted by Fore and Aft

ferrailleur how about letting her dry out a bit before you fill all those blisters? Some people do not like moisture meters but I certainly like to use them in situations like this. The first reading gives you a starting place and then a week later get it read again and there should be a difference. When I was a boat builder and I was in a rush I would use a heat gun on individual ground out blisters to help dry them. (You have way to many) When I used the heat gun you would always see some moisture rise to the surface and evaporate.
Cheers

I often spray high pressure water to flush out the bad stuff from the opened blisters. They will be dried before the next step.
Interesting: as I was grinding I could see the blister liquidly stuff just being evaporated because of the grinding heat.

[ferrailleur]

Originally Posted by Don C L

You know, I was reading about the yellow goo coming out of the blisters being acidic and a catalyst for the reaction that generated the blister. We used baking soda wash on the blisters and they bubbled up quite a bit and then we washed them out. I THINK they dried out much better that way since the acidic liquid did not seem to dry out too well. I've never heard of anyone else applying a neutralizing bath, so we might be crazy.

As I was grinding the bigger blisters I could see the yellowish stuff being just evaporated under the grinder wheel heat!
I will pressure re-wash the whole hull with TSP before any epoxy barrier treatment.
THANKS

[timeout2]

You really need to fair the bottom before barrier coat.
West 105 is a convenient system. 205 hardener doesn't have a lot of pot life meaning small batches and work fast. 206 slow hardener is a better choice for large areas.
406 filler is waterproof and very hard. ie difficult to sand. 410 microlite is not waterproof, very easy to sand. You will be putting waterproof barrier coat on top.
If you put a barrier coat on, then discover the bottom isn't fair, you will probably have to sand most of it off in order to get a good chemical and mechanical bond for the resin.

I faired first and the sanding was NOT a fun job.

[keelsidedown]

Just a quick question...

How did the soda blasting go? Looks like it took it down to the gel coat pretty well (don't know how much of that is your grinding).

Interested because I might want to use soda blasting to prep a hull for an application of copper coat.

Thanks for the off topic...

[ferrailleur]

Originally Posted by keelsidedown

Just a quick question...

How did the soda blasting go? Looks like it took it down to the gel coat pretty well (don't know how much of that is your grinding).

Interested because I might want to use soda blasting to prep a hull for an application of copper coat.

Thanks for the off topic...

Loved the soda blasting job..... removed many coats of old paint which hid all those blisters. The lazy me says I shouldn't have done and live with the blisters I didn't even know existed!
But I will be happier with a restored sound hull!

[seandepagnier]

I had at least 100 blisters, and the largest 12 were more than 1ft across. A few were 2ft long and bulged out 1 inch or more. All I did was drill a tiny hole in the largest ones and watch the water shoot out 10ft or more.


That was 10 years ago, I since crossed pacific, indian and atlantic ocean.


I think you are wasting your time, making toxic dust, and wasting chemicals filling them.


No boat ever sank because of blisters.

[thinwater]

Originally Posted by boat_alexandra

I had at least 100 blisters, and the largest 12 were more than 1ft across. A few were 2ft long and bulged out 1 inch or more. All I did was drill a tiny hole in the largest ones and watch the water shoot out 10ft or more.


That was 10 years ago, I since crossed pacific, indian and atlantic ocean.


I think you are wasting your time, making toxic dust, and wasting chemicals filling them.


No boat ever sank because of blisters.

He makes an interesting point. In fact, most surveyors will tell you that for blisters to do structural damage is really quite rare.


And since more are likely to pop up, a good repair makes sense, but losing sleep over it probably does not.

[Hardhead]

You've put some work in there, that's for sure. Strangely, there is nothing like sanding bottom paint, or grinding blisters, to make you love your boat.

You also now have impressive character. Good work!

[Clivevon]

Ideas offered for consideration from my own experience. I didnt do what you are doing, i just threw a shedload of money at the problem because I could - it worked but still hurt though.
Looks like you are doing it all yourself? You dont mention anything about moisture readings? If I were you I would buy a good moisture meter (I bought a Tramex Skipper Plus, available on Amazon for $446.) Given the amount of work gone into the boat it would be nice to be able to keep track of your own moisture readings whenever you like, & compared to the effort you will be putting in, the cost is very cheap. Nothing else will give you that information.
Whatever you do to fill & fair the hull, it will be a temporary patch. The problem wont have gone away & the blisters will come back.
If you seal all the moisture in the hull so it can no longer get out, then it will just go deeper in.... Blisters dont sink boats, but internal fibreglass delamination will certainly weaken the hull below original designed strength. Nice to know next time you pound the hull in bad weather.
Nothing wrong with the approach you are taking, just so long as you know it is temporary & you will have to keep on doing it. Meanwhile you can go sailing, haul the boat for 3 months to dry out over every winter, & use your moisture meter to keep an eye on what is going on. Good luck.

By the way, high pressure water is forcing more water into the hull. Try steam cleaning instead. & if you want to apply consistent heat on the hull, infra red heaters are the way to go - cheap to buy & they only heat what they are directed onto, not the air in between, so no heat loss.

all this is not a permanent solution. The only "permanent" solution starts with drying out the hull thoroughly. But it can keep you going for years.