Barrier Coat question

hookemaster19

New Member
Jun 4, 2020
6
Boat Info
1988 300 Weekender
2002 410 Sundancer
Engines
300- twin Crusader 350's Direct Drives
410- twin Cat 3126's
I had my bottom paint scraped off and getting prepared to do the rest of the work.
When you start sanding the bottom how cleaned off does it have to be???
 
If you are asking because you want to roll on barrier coat, then completely paint free.
 
8C0B32DE-19B1-4BF9-A4CF-5D2A1E658DA9.jpeg
5929BDD2-831F-4493-A891-B7D2EBF6E8DA.jpeg
8C29E43C-63C6-4361-89DA-0C51DEA5DD49.jpeg
If you are asking because you want to roll on barrier coat, then completely paint free.

Yes I needed to do A complete strip down on a older weekender I bought just for fishing.
Here is where I am at after stripping and power washing down.
 
We have ours done every 6 years. Its sanded, but never gets took down all the way to the hard coat. pressure wash as soon as it comes out of the water to clean, Tape off paint line, Sand with 100 grit, Wipe off residue and roll it on. Never had a problem or a blister.
 
Barrier coat needs a frosty dull paint free surface. It appears you have more of a pigment stain left than paint, but hard to tell in pictures.
 
Just to be clear, by “Barrier Coat” you mean multiple coats of a two part epoxy like Pettit 4700/4701 that would be followed by multiple coats of anti-fouling bottom paint?

If the answer is yes, then from the photos it would appear you have a long way to go. Ideally a freshly cleaned with a uniform gelcoat color (soda blasted, for example) and roughened surface is the best preparation.
 
I think the key is a quick/timely/good power washing if you are only applying new anti-fouling paint. Then sanding of course.

Just for fishing? I would not worry about going that far if I were you, anti-fouling only after good prep.
 
I would not do the barrier coat unless you had problems like blisters. The anti foul is what just needs washing and sanding. A company on on our lake sandblasted our 450, put on the barrier coat then the anti foul. Had major blisters in 1 year. The boat is still sitting on blocks waiting for the moister levels to come down for re painting. Don't mess with the hard coat unless you have a problem. It was a lesson learned for me the hard way.
 
I would not do the barrier coat unless you had problems like blisters. The anti foul is what just needs washing and sanding. A company on on our lake sandblasted our 450, put on the barrier coat then the anti foul. Had major blisters in 1 year. The boat is still sitting on blocks waiting for the moister levels to come down for re painting. Don't mess with the hard coat unless you have a problem. It was a lesson learned for me the hard way.


I am having a barrier coat, petit 4700 put on my vessel soon and have a question???
If your vessel was blasted and had a barrier coat applied what caused the subsequent blisters?
Thanks
 
The strict definition of a blister is where moisture as gotten into the fiberglass and caused a delamination. Blisters are more common with older types of fiberglass. Your 01 should be new enough to have been made with the newer glass formulation.

The pock mark like voids that are exposed by soda blasting are actually voids created by bubbles in the gelcoat. These are normal.
 
I had no blisters to begin with, I was a newbie and just let them sand blast the bottom and do what they said I needed, Of coarse blasting, barrier coat and then anti foul was the most money. Either the bottom was not dry when they put the barrier coat on or the bottom was not completely covered. Either way there was moisture between the barrier coat they put on and the original gel coat.I think they blasted through the gel coat and got into the fiberglass and that were the problem was.
 
The strict definition of a blister is where moisture as gotten into the fiberglass and caused a delamination. Blisters are more common with older types of fiberglass. Your 01 should be new enough to have been made with the newer glass formulation.

The pock mark like voids that are exposed by soda blasting are actually voids created by bubbles in the gelcoat. These are normal.
I had no blisters to begin with, I was a newbie and just let them sand blast the bottom and do what they said I needed, Of coarse blasting, barrier coat and then anti foul was the most money. Either the bottom was not dry when they put the barrier coat on or the bottom was not completely covered. Either way there was moisture between the barrier coat they put on and the original gel coat.I think they blasted through the gel coat and got into the fiberglass and that were the problem was.


so I actually have 2 boats, an 01 290 Sundancer and a 90 Regal 360 commodore. It is 90 regal that I am having the bottom blasted to remove the soft ablative paint used in fresh water followed by an application of 3 coats of Pettit 4700/4701 barrier coat and 3 coats of Trinidad Xd since the boat has been moved from Lake Michigan to the space coast of Florida.

How much time transpired between the blasting and application of the barrier coat on your vessel?

What product was used?

And finally, any advice or insight?

Thank you.
 
Gelcoat is porous and not waterproof. The barrier coat is what adds the protection. Frankly, you need to return to the yard/contractor and have them make the work right. It could have been application but I have seen some product failures as well. Either way you did the right thing so I don’t want there to be confusion as to what should be done. Your experience is rare and shouldn’t be taken as don’t do a barrier coat because mine failed.

Just remember these threads often last years and we want to provide guidance for the long-term.







I had no blisters to begin with, I was a newbie and just let them sand blast the bottom and do what they said I needed, Of coarse blasting, barrier coat and then anti foul was the most money. Either the bottom was not dry when they put the barrier coat on or the bottom was not completely covered. Either way there was moisture between the barrier coat they put on and the original gel coat.I think they blasted through the gel coat and got into the fiberglass and that were the problem was.
 
so I actually have 2 boats, an 01 290 Sundancer and a 90 Regal 360 commodore. It is 90 regal that I am having the bottom blasted to remove the soft ablative paint used in fresh water followed by an application of 3 coats of Pettit 4700/4701 barrier coat and 3 coats of Trinidad Xd since the boat has been moved from Lake Michigan to the space coast of Florida.

How much time transpired between the blasting and application of the barrier coat on your vessel?

What product was used?

And finally, any advice or insight?

Thank you.

Our 02 280 had badly applied anti fouling in that it kept flaking to the gelcoat in sections. To remove it completely I had the boat soda blasted in the fall shortly after it was hauled for the winter. The boat sat outside (Boston area) until it was warm enough in the spring to paint with 4701 and bottom paint. I elected to use the epoxy as the alternative would have been to respray the bottom with gelcoat to correct the profile created by the blast.
 
My advice is if you don't have blisters and the bottom hard coat looks good, Wash, Sand and re coat with the anti foul paint. In freshwater where I am this is common practice and has worked well.
 
You need to read the application instructions from the manufacturer.
 

Forum statistics

Threads
112,948
Messages
1,422,805
Members
60,930
Latest member
Ebrown69
Back
Top