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Bottom prep issues

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glivs
Admiral

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USA
822 Posts

Initially Posted - 05/18/2017 : 20:25:37

Short version of a longer story I may post later - I took advantage of some time this spring to strip the bottom and prep for new bottom paint. Great Escape is an '89 wing keel that has always been sailed in freshwater in the northeast (NY, VT) and seasonally hauled and stored on its factory cradle. I don't know whether the bottom ablative paint has ever been stripped in the past but there is no evidence of it. I used Franmar's soy strip followed by a wipe down with Interlux solvent. Bottom is now baby bottom smooth. A quick conversation with Gerry Douglass at Catalina revealed the bottom is original "booster guard gelcoat". As per his recommendation I faired and sealed the keel with epoxy. It's now time to tackle the remainder of the bottom. One (maybe two) issues. (1) Parallel hairline stress cracks inboard of the port cradle pads - three to four in number and about 6-8" long plus a long (10-12") crack from forward edge of both rear pads arching towards the aft end of the keel. I tried to photograph them with a macro lens but they are so fine the pics didn't show them (Grey overcast day). (2) Osmotic blisters (?) below the water line about 3/16" diameter and just barely perceptible both visually and to touch. Over most of the bottom there are none but forward of the keel they are two to three per sq.inch. I don't have the resources to restore to pristine condition and will likely only tackle the stress cracks at this point. Thoughts? Widen cracks, epoxy and then barrier coat entire bottom?

Gerry & Leslie; Malletts Bay, VT
"Great Escape" 1989 C-25 SR/WK #5972

cat25
Navigator

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USA
140 Posts

Response Posted - 05/19/2017 : 09:01:43

After all the work you did on the bottom I would do what your thoughts are.My boat was purchased in fresh water. I had the bottom baking soda striped and barrier coated. The boat was bottom painted for salt water no more problems.

Ken
Chenango~
1990~TR~WK~C25~#6022
Candlewood Lake, Ct

OLarryR
Master Marine Consultant

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USA
3368 Posts

Response Posted - 05/19/2017 : 09:22:21

I'll leave it to others regarding the stress cracks. In regards to the blisters - The story goes that most blisters are generally only a cosmetic concern unless they go further in, past the gel coat.

I believe most Cat 25s do not have issues with blisters but I have an '89 and had significant issues with blisters which I kept an eye on during annual pressure washings (I also have my boat in freshwater year-round). I use ablative/copolymer bottom paint and so I have the boat in for repainting every 3-4 years. Based on the blisters which had advanced to nickel and quarter sized and many of them, I decided to bite the bullet and get them squared away, then bottom waterproofed. Below is link to repairs. The blisters went well into the laminate and as one blister was removed, there would be another one nearby. Result was that this was not just a simple remove blister and epoxy the spots. Since so much laminate was removed in 1-2' sections over 1/3 of the hull, the yard re-laminated whole sections with fiberglas matte and resin - As you can see from the photos.

If your blisters are small, just keep an eye on them and see if they grow and appear likely to have penetrated the gel coat. Hopefully, you will not have to go down the path I decided. On the other hand, if you assess that waterproofing the bottom right now would be fairly easy as the blisters are not much to contend with...well then you may be able to head off bigger issues years from now by attending to it now.

http://catalina25.homestead.com/BlisterRepairWaterproofing.html

Larry
'89 Robin's Nest#5820, Potomac River/Quantico, Va
http://catalina25.homestead.com/olarryr.html

Stinkpotter
Master Marine Consultant

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Djibouti
9013 Posts

Response Posted - 05/20/2017 : 08:39:28

I have to wonder about barrier coating over blisters... I'd want to get some "expert" opinions on that.

Dave Bristle
Association "Port Captain" for Mystic/Stonington CT
PO of 1985 C-25 SR/FK #5032 Passage, USCG "sixpack" (expired),
Now on Eastern 27 $+!nkp*+ Sarge

OLarryR
Master Marine Consultant

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USA
3368 Posts

Response Posted - 05/22/2017 : 04:04:47

I would advise not barrier coating over blisters. If you have very few blisters, then perhaps taking care of those and then barrier coating would work. However, the issue is that if there is water in a blister and the blister is not removed, there is possibility that after it is sealed in with the barrier coat, that a freeze in the winter may cause the water in the blister to expand and that might disturb the integrity of your barrier coat.

Larry
'89 Robin's Nest#5820, Potomac River/Quantico, Va
http://catalina25.homestead.com/olarryr.html

glivs
Admiral

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USA
822 Posts

Response Posted - 05/25/2017 : 18:34:02

Excuse the delayed response - life is complicated at the moment and the boat has low priority (as does the yard ....)

I hear you. I do not pretend any expertise in this area which is why I spoke with Catalina engineering, the boat yard owner, the yard's bottom prep technician and a couple of long time sailors with far more experience than I before beginning. The response was unanimous- the blisters (?) are barely perceptible and so readily sanded out (1-2 quick passes with random orbital sander) the recommendation was to sand them out, thoroughly wash the hull and paint the bottom with sealer. I also washed that area several times with solvent to try to draw any moisture to the surface and waited three weeks before painting. I tried to locate/ borrow a moisture meter but no luck.

My primary purpose in writing, however, was to alert others that what you see looking at bottom paint does not necessarily represent what lies underneath....and that seasonally hauled boats can have surprises.

Comments welcomed although it may be some time before I can respond again.

Gerry & Leslie; Malletts Bay, VT
"Great Escape" 1989 C-25 SR/WK #5972

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The Officers, Staff and members of this site only provide information based upon the concept that anyone utilizing this information does so at their own risk and holds harmless all contributors to this site.