Should I add fiberglass

Grumps

.
Mar 4, 2021
18
Macgregor 25 Trailer
I have a Mac 25 and the previous owner left it in the water without bottom paint. A lot of blistering, so I have stripped it down to the fiberglass. The question I have is if I should add a layer of fiberglass to the hull while I have the opportunity? I do not know how thick the Mac 25 hull is and haven’t been able to find much info about it. Any input is greatly appreciated.
 
Jan 19, 2010
12,362
Hobie 16 & Rhodes 22 Skeeter Charleston
Someone will correct me if I am wrong but I think the correct next step is to put two or three coats of epoxy barrier coat over the exposed fiberglass and then bottom paint.
 

Grumps

.
Mar 4, 2021
18
Macgregor 25 Trailer
Someone will correct me if I am wrong but I think the correct next step is to put two or three coats of epoxy barrier coat over the exposed fiberglass and then bottom paint.
That is my plan. I have Coppercoat and epoxy barrier coat to apply. I just can’t help myself from thinking about adding a layer of glass while it’s stripped.
 
Jan 19, 2010
12,362
Hobie 16 & Rhodes 22 Skeeter Charleston
If I were itching for a project (pun intended) I would go with a layer of Kevlar on the bottom if I was going to all the trouble anyway.
 

Grumps

.
Mar 4, 2021
18
Macgregor 25 Trailer
If I were itching for a project (pun intended) I would go with a layer of Kevlar on the bottom if I was going to all the trouble anyway.
Now, there’s an idea... may have to do a little research...
 
Jan 1, 2006
7,040
Slickcraft 26 Sailfish
Only you can gauge how much laminate was lost in removing the gel coat and blisters. And, the method of removal. If you sanded you probably didn't over do it. With sand blasting you could. Putting a layer of glass or whatever material will be a lot of work for a DIY'er. Getting it smooth will be even more work.
 
Nov 30, 2020
79
Macgregor 22 Dania, FL
The hull of my Mac 22 is approximately 1/4 inch thick. Measured when I added a garboard drain. This may help you judge.
Chip V.
 

Johnb

.
Jan 22, 2008
1,420
Hunter 37-cutter Richmond CA
My 1976 Clipper Marine 23 developed a bunch of blisters starting in about 1989. None were bigger than a quarter. On being popped a liquid smelling like resin came out.

For 2 years it was an annual event to scrape them out, dry with a hair dryer, sand and paint with polyester resin.

None of those repairs failed. I eventually sold the boat in 1999. It was kept in fresh water for that whole time.

This is to make the point that your course of action may be very simple.
 
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Jun 8, 2004
10,024
-na -NA Anywhere USA
One main thing. Cut blisters out and let the hull dry out for several months to allow moisture in the fiberglass to dry out. Then fill in with two part epoxy and sand smooth. Then apply several layers of epoxy barrier coats. Then apply anti fouling paint
 
Jan 19, 2010
12,362
Hobie 16 & Rhodes 22 Skeeter Charleston
One main thing. Cut blisters out and let the hull dry out for several months to allow moisture in the fiberglass to dry out. Then fill in with two part epoxy and sand smooth. Then apply several layers of epoxy barrier coats. Then apply anti fouling paint
Dave! That’s three things:):beer::beer::beer:
 
Apr 26, 2015
660
S2 26 Mid On Trailer
I need a little more data on how far you stripped. Did you strip the gelcoat off only, which should have left small voids where the blisters were in the chopped strand mat? Or did you strip a lot of mat off so you no longer see where the blisters had infiltrated the mat?

The mat doesn't add a lot of structural strength, but does keep the oil canning at bay somewhat, and helps eliminate print through of the weave. Mac 25s where built to a price point and the hulls were not the thickest and already had some flex in them.

I'll watch for your answer and then give you some ideas. I've saved some hulls and I've scrapped some hulls. I'm also crazy enough to have $24000 in a $7000 boat and have never gotten a return on investment on any old boat I've repaired. But It's a hobby and I enjoy doing it.
 
Sep 24, 2018
2,549
O'Day 25 Chicago
If I was worried about structural strength I'd add cloth to the inside of the hull. It's a lot less work than trying to sand it smooth