Bottom Paint Corrosion around Strainers

Bill_N

Rear Admiral
Joined
Mar 20, 2012
Posts
1,632
Likes
511
Location
Eastern Ct
Boat Make
31' JC Rowdy Girl
I have these areas of bottom paint corrosion around the strainers on my JC. I sanded the areas and barrier coated them when I got the boat but it didn't resolve the problem. I went through the bonding system and cleaned up the connections last year. I also installed a galvanic isolator in June. I was hoping for less corrosion this year but not much has changed. Any suggestions?

The main strainer

zo3srKz.jpg


The vacuflush strainer

sDPgI4C.jpg


The washdown strainer

Q9uHRRJ.jpg
 

ARC

Captain
Joined
Sep 30, 2017
Posts
707
Likes
619
Age
66
Location
great South Bay
Boat Make
31’ eastern Casco Bay
Bronze strainers , copper paint . Paint loses. I have seen this on a few boats. I bet there is no strainer damage. You could try a paint with less or no copper .
 

Bill_N

Rear Admiral
Joined
Mar 20, 2012
Posts
1,632
Likes
511
Location
Eastern Ct
Boat Make
31' JC Rowdy Girl
Bronze strainers , copper paint . Paint loses. I have seen this on a few boats. I bet there is no strainer damage. You could try a paint with less or no copper .
Good point. The paint is Hydrocoat that has 40% cuprous oxide as the active ingredient. I'm going to sand those areas this springs. Put a couple thin coats of barrier coat on and use a copperless paint in those areas.
 

jplob96

Lieutenant
Joined
Feb 18, 2012
Posts
56
Likes
10
Location
Clinton, CT
Boat Make
28 ft. Crowley Beal
Good point. The paint is Hydrocoat that has 40% cuprous oxide as the active ingredient. I'm going to sand those areas this springs. Put a couple thin coats of barrier coat on and use a copperless paint in those areas.
I have the exact condition when boat is hauled out for season. Used Hydrocoat in the past but have been using Seahawk Monterey ablative the last four years. Same result.
 

speedwagon

Commander
Joined
Dec 10, 2014
Posts
378
Likes
157
Location
RI
I use Hydrocoat but don't have those issue. Thru hull and strainers are not bonded. I aslo barrier coated the strainers and painted with Hydrocoat.
 

Genius

Admiral
Joined
Feb 11, 2016
Posts
4,797
Likes
3,217
Location
Rhode Island
First Name
David
Boat Make
32 Morse Cove
I don't think it is associated with bonding or any type of galvanic action. There is no pattern around the fixtures and the metal doesn't look affected. I think you are having paint failure because water is behind the substrate? Is the hull cored or solid glass?
 

ThePartsGuy

Commander
Joined
Feb 11, 2018
Posts
292
Likes
277
Location
NEWBURYPORT MA
Website
www.merri-maryachtbasin.com
First Name
BILLY
I don't think it is associated with bonding or any type of galvanic action. There is no pattern around the fixtures and the metal doesn't look affected. I think you are having paint failure because water is behind the substrate? Is the hull cored or solid glass?
I see why they call you Genius! lol

I agree. It looks like you can see some of the black paint that didn't fall off yet has heavy scaling under it. Meaning a very "chunky" lawyered finish and not a smooth sub substrate.
 

Bill_N

Rear Admiral
Joined
Mar 20, 2012
Posts
1,632
Likes
511
Location
Eastern Ct
Boat Make
31' JC Rowdy Girl
The original owner used Petit Trinidad which is a hard, high copper content bottom paint. The flaking around the strainers was evident when I bought the boat and there was a lot of build-up on the entire bottom. I sanded the bottom to remove some of the build up and smooth it out and started using Hydrocoat at that time which is 7 seasons now. There's no water under the paint but I don't know how well the re-coats were prepped. I'll treat as I stated above this spring and see what happens this season.
 

Genius

Admiral
Joined
Feb 11, 2016
Posts
4,797
Likes
3,217
Location
Rhode Island
First Name
David
Boat Make
32 Morse Cove
The original owner used Petit Trinidad which is a hard, high copper content bottom paint. The flaking around the strainers was evident when I bought the boat and there was a lot of build-up on the entire bottom. I sanded the bottom to remove some of the build up and smooth it out and started using Hydrocoat at that time which is 7 seasons now. There's no water under the paint but I don't know how well the re-coats were prepped. I'll treat as I stated above this spring and see what happens this season.
Bill,
Is it a cored hull?
 
Top Bottom