Interesting article on the obsession w/blisters

[matane]

Should any of you read the article- this man is the grandson of one of the first fiberglass boat fabricators.
Makes me feel much more at ease.
http://www.yachtworld.com/mustangyts/mustangyts_5.html

[sloopjohnl]

nice article, although i did strip the gelcoat only from the bottom of my '76 typhoon due to small, numerous blisters, followed by West system epoxy and barrier coat. 12 years later nary a blister. the article does give me new appreciation of the very slight print through i notice on the topsides and coach roof when i wash and wax each spring and i think i will leave the very few, tiny blisters just above the waterline at the stern counter alone as i have noticed no changes in twelve years! thanks for sharing.

[Keith]

Great article! I was almost convinced by others to strip the bottom paint and barrier coat my 33 year old CD 30 C even though it has no signs of blisters. This article has made the decision to just roll on some fresh bottom paint and enjoy.

[moctrams]

Last summer I had the bottom of my CD30C soda blasted and barrier coated. The soda blasting revealed a previous repair to the rudder shoe. I had noticed the weeping of “something” around the shoe when I laid the boat up each winter. That was the main reason, beside getting off the old bottom paint and going with“green” bottom paint. The soda blasting did not reveal any blisters and I feel much better now that the rudder shoe is fixed. When I haul the boat I make sure the yard does not block the boat up sitting on the rudder shoe. Oh, by the way, starting 2013 season, our marina does not allow anything but environmentally friendly bottom paint. New laws concerning banning cuprous copper bottom paint are coming to the Chesapeake Bay.

[matane]

Thats good to hear about the laws passed in Ch. Bay- Cu is toxic at certain levels- since it is used in swimming pools as an algicide, they always have you wait, then test before swimming. I don't even know if there are many Cu algicides any more.

Anyway- what I took away from the article was that in most cases they are benign aside from slowing the boat some- which anti fouling paints do anyway. Prior to reading the article I sent the surveyor an email explaining my ignorance of year round wet boats
and blisters and the sky is falling... and interestingly- he basically said exactly what the author said- it can be a good bargaining tool. Another thing- speaking of Cu anti fouling- accurate moisture tests cannot really be preformed when a boat has the Cu anti fouling because of the electrochemical effect of Cu- it throws the meter off.
Another ignorant question I have- when I see oldish, not new, sailboats on the hard, and they have new or newish bottom paints- I rarely see a smooth surface- if ever- unless it was a complete restore. I'd have to show pictures to show what I'm talking about- Since this seems common- what is this exactly?

[moctrams]

This is pic of the barrier coat after fairing.

Gabby Barrier.JPG

[barfwinkle]

good article.

Happy New Year to all

[Dick Villamil]

Excellent article that will be placed in my boat repair folder. However, for what it is worth I had no problems with my older 1968 Morgan 24. My 1976 O'Day 27 only had water in the rudder from an unknown source. I drilled holes in the bottom of the rudder to let the water drain out. Finally I sanded it down and applied a barrier coat and the problem was solved. My 1979 C&C 34 was diagnosed with moisture problems in the hull below the waterline when I had it surveyed prior to an attempted sale 7 years ago. The deal fell through and I had to have 1/2 of the outer fiberglass skin removed exposing a mushy and partly rotten balsa core - according to the repair yard - possibly through a defect during manufacture but also possibly due to a grounding that wasn't obvious when I bought the boat in 1989. After removing the multiple layers of bottom paint there were no blisters but there were micro cracks that were produced by keel flexing and possibly damage from the grounding. The boat has since been fully restored better than new and has been completely barrier coated to prevent any additional moisture intrusion into the balsa core - and she wins a lot of races! I also resoored a 1976 Cape Dory Typhoon - after removing MANY layers of bottom paint it revealed several cracks in the outer geloat and laminant that evidently were from an altercation with a dock. The rudder shoe area was so wet and punky I could scrape it out with a spoon! Eventually I could put my hand through the carved out area as well as discover that there had been water between the hull and lead ballast - and the freeze-thaw cycles opened cracks further and could have led to small cracks in the hull. Once that void was drained, dried and filled with resin and the rudder shoe area filled and glassed over it was only natural to sand the entire hull and fill in any cracks in the gel coat that were discovered - and there were many. Three coats of barrier coat later and 6 years of sailing - the bottom looks as good as new and the bilge is dry. Therefore - even though there was a lot of work involved, the boat is now very seaworthy and is admired by those who see it out sailing. Older boats may be solid but it is worth doing an investigation that may reveal previous issues covered up by many coats of bottom paint. I have just finished restoring an early CD10 and discovered a multitude of spiderweb cracks in the outer gel coat and fiberglass layers (possibly caused by flexing of hte thin hull. These were dremelled out and filled followed by another 3 coats of barrier coat. She was launched last year and is now more solid than when new. My only problem is how to make enough time to sail all three boats while I start to restore an early 1970's Sunfish for the grandkids!

[Shinok]

The big issue with blisters for me is that it represents either negligence or poor construction. I've yet to see a boat yet that had blisters and didn't have other substantial issues "hiding", that is just my limited experience though.

[matane]

Shinok- That is a good point. Especially regarding the manufacturing.
Dick- As for CDs the heel where the rudder joins the keel- As you saw on my "rudder issue" post- and the responses-
this seems to be a sensitive area. As for your C&C- I have never heard of a hull- mold aspect- using balsa core.
As far as I know- there is the female mold- some sort of slip agent is put around the mold, followed by gelcoat, followed by layering of fiberglass/resin/fiberglass/resin - the whole mat and cloth procedure. This forms the hull- no wood. I have seen fishing boat hulls built. The older fishing boats had wood stringers that go the length of the boat on each side of the centerline, and are on top of the first layers of cloth/resin. They are part of the V structure support of the hull, and are layered- cloth/resin/cloth/resin etc- I restored a '78 23ft SeaCraft and they used wood stringers in the Potter Yard built SeaCrafts up until 1980. After I bought the boat and began the restoring project... I discovered termites and completely freaked out "omg my stringers are being chewed!!!". Fortunately it turned out to be only on parts that were in the console or other non structural wood. The stringers had so many layers of cloth/resin/cloth/resin- that termites would have had to have drill bits. Now they use foam stringers and lay the cloth/resin. I know of Boston Whalers, and other fishing boats that use foam that is the inside of a laminated fiberglass sandwich- the so called "unsinkable Whalers" (I have a '71 17ft Whaler- for sale now) This is a concern- if for some reason the fiberglass was pierced or cracked, and the foam absorbs water-and it is a nightmare. This is easily detected by looking at how the boat sits in the water. Anyway, as I have said- there are some things about sailboats- especially fins- that I am totally unfamiliar with. Some fins are simply pure iron, and bolted to the hull- have no idea how that works.... The CDs- the manuals review the construction of the hulls. I believe it is as I described above with a female mold, and the (lead?) keel is encapsulated by - I forget- epoxy? The deck, cockpit sole, other above deck areas have core, but I do not know of wood cores in the hull manufacturing process.
Back to blisters....
In the northern areas, I would imagine that the blisters freeze and thaw, and expose the fiberglas/resin.
btw- The guy is surveying the boat tomorrow- so we shall see.

[Keith]

Glad you mentioned that. I had never heard of balsa core in the hull only in the cabin top and deck.

[moctrams]

Cabo Ricos have balsa cored hulls. A friend of mine had his stripped and layed up foam and mat and a barrier coat.

[jbenagh]

That was a fun read, but I think he is mistaken on the relative advantage of mat vs. woven cloth. Chopped strand mat is the strongest fiberglass fabric you can use for yacht repair. It's even stronger if you blow fibers into a space and laminate them as was done on our boats. Fiberglass cloth provides very good abrasion resistance but not much strength except along the lines of fiber. The mat, with its random arrangement of fibers, is generally stronger in a hull-building application.

Sorry for the borderline lecture, but I would hate to see someone repair a hull based on his recommendation. When in doubt, see the West System repair manual -- it has never served me wrong.

Jeff

[Shinok]

Cabo Ricos have balsa cored hulls. A friend of mine had his stripped and layed up new roven woven and a barrier coat.

IIRC some Tartan models do as well, mostly newer ones.

[moctrams]

The following is from the CDSOA web site.

http://www.capedory.org/reviews/nqarticle/index.html

The hull is laid up in a single mold mounted on a rotating frame to permit easy access and near-horizontal surfaces for best resin distribution. To make possible the construction of an integral inbound lip for attachment of the deck/coach roof molding, a separate and detachable flange section is bolted onto the mold. The lip is laid up inside this section of the mold, which is then removed to permit extraction of the completed hull.
The layup is conventional alternate layers of hand-laid mat and roving, tapering from a total of 15 layers at the keel down to 10 at the topside flange. A chopper gun is, however, used to set the first layer behind the gel coat on the hulls and to a greater extent in deck laminates; but to minimize the possibility of gel coat stress cracks at coach roof corners and cockpit coamings, unidirectional glass strand is laid in as reinforcement.