Blisters

Allan,

Excellent! Really nice to know that and now have one less thing to worry about. If you have a Vinylester hull it would make no sense to spend the time or money applying a barrier coat.

I assume you saw him at the Philly Strictly Sail Boat Show. See anything interesting?

Bruce

Somerset 671 SoCal

 

 

I talked with Gerry Douglas about this last evening at the Philly Boat Show. According to Gerry, the 320's are laid up with a 3/16" outer layer of vinylester. Vinylester is 100% impervious to water penetration; he was most adamant about this. There is no water osmosis through vinylester. Under the vinylester is the old polyester that, if water was to get to it, would react with the resin, form acid and blister. He was unsure of the year that

the 320 went rubrail-to-rubrail with vinylester but that seems to be addressed below.

 

Allan S. Field

Sea Shadow - #808   Columbia, MD

 

 

Ahh, blisters and the Catalina 320.

Catalina had a major blistering problem on hulls built in late 1995 and 96. All C320s have been built using vinylester laminate which is a vapor barrier against osmotic blisters. The blisters that were a problem were not osmotic blisters and the hull was dry. The blisters formed in a blue "back up material" that is between the gelcoat and the "skin coat" (vinylester resin). There were many, many small blisters the size of a pencil eraser.

 

I have records, gathered from this list, on 26 hulls between #319 and #419 that reported the problem. Gerry Douglas published a 2 page detail fix for the problem. The fix was

basically peel the gelcoat including the blue material then rebuild the outer hull (that is a gross oversimplification). As I understand Catalina paid for everything.

 

Sadly, I know more about this than I would like, but Blue Canute has a bullet proof bottom.

 

John & Jeanine Giddings

Blue Canute C320 # 380  Greenwich, CT

 

 I have a Catalina 320 1998, this year, I have remove all the antifouling on  the bottom. It can be a good time to make an antiblister protection  (Interprotec). I know that some boats and years need it. Does Catalina 320  boat need this protection to be added?

 

 Thank

 Stephane

 

 

Unfortunately I could not find my prior emails on this subject but my hard copy file (one inch thick) on blisters had all the data.

 

During the winter of 97-98 it was discovered that Blue Canute #380 had blisters... thousands of them about a quarter of an inch in diameter. I was not surprised because this list had already reported the problem. I got deeply involved in the problem and the fixes. There were many twists and turns because Frank Butler had never seen labor rates as high as here in Fairfield Co., CT. In the end Gerry Douglas was a great help.

 

The Problem: Starting in 1995-6 (about hull # 319) Catalina changed its hull manufacturing process. From the outside in the hull had 4 layers, this may have been when they switched to Vinylester Resin. The 4 layers were:

1. Gelcoat

2. "Back up material": a blue material made by 3M to be a binder between the Gelcoat and the 3rd layer.

3. "Skin coat" coat or coats of Vinylester Ester Resin

4. Laminates

After a period it was discovered that small blisters could form in the 2nd coat (Blue Back up material) between the Gelcoat and the Vinylester Resin. These were not the traditional osmotic blisters that form in the laminates (layer 4). The hull was dry because it was protected by the Vinylester Resin. However we had blisters that needed to be removed under warranty.

 

The Fix:  The steps involved in the blister repair (written by Gerry Douglas) as revised 1/28/98 are:

1. Remove all gelcoat (including the blue layer) by peeling, do not remove Vinylester Resin.
2. Clean and dry hull.
3. Apply a seal coat of 3M dual purpose resin.
4. Fill voids or irregularities... with 3M marine premium filler.
5. Apply the 3M marine water barrier coating.   ... 3 coats to the desired thickness of 15 mills.
6. Apply bottom paint.

 

My notes:
Sounds simpler than it is.
Sanding is required after steps 1,3,4 and potentially 5.

The scope of the problem: In my years on this list I have recorded 25 separate C320's with this type of blisters. They are all between hulls 319 to 419.

From the repair directions it appears that most other Catalina's had the problem. As far as I know Catalina stood by its warranty in all cases, it just took 6 months in my case.

 

John Giddings
Blue Canute  C320  #380   Greenwich,  CT

 

 

Note: Minor hull blisters rumored to have been reported between hulls 319-417. Jeff Hare