Charlie,

Do you know what the PO used for the first barrier coat? I have read a report from an “expert” that using different products for successive barrier coats can create problems with blisters. It could be incompatibility of the two products or poor adherence between the two or the first one was done poorly and the second was a bandaid that just delayed the blisters from the original. Just too many variables. Getting a tech from Interlux sounds like the best next step. Worst case scenario you may have to strip down past the first barrier coat and start from fresh glass.

If you’re interested I’ll see if I can dig up a link to that report.

Skip

Interlux both times. Well, guess that at least eliminates one issue but still leaves a mystery as to why the new blisters.

Before I did my bottom I tried to research every opinion and report on the internet and decided to shave the bottom instead of blasting. Was extremely pleased with the results. Again at least some of the “experts” opine that blasting leaves a lot of broken fibers, small voids, rough places etc that can be spots for new blisters to start forming.

Also the guy that did mine, before applying the epoxy first applied some other kind of sub coat which I don’t recall the details. Will ask him what that was.

Skip

Charlie,

Silverheels spent her first 15 years in the Great Lakes, and then
moved to Florida. When I got her 8 years ago, she had a plethora
of tiny blisters only in the gelcoat along the forward waterline,
and a half-dozen dime-to-quarter-size scattered around the
bottom, all in the gelcoat. In 2011, I had a guy here who
specializes in boat bottoms (called Bottom Dave – really!) grind
it all down to either good gelcoat or no gelcoat, about 50/50
overall. Then I left the boat on the hard for about 5 months
while I went off to do some land traveling. In the fall we filled
the blisters and rolled on 3 coats of (I think it was) Sea Hawk
brand barrier epoxy. Have had no blisters since then, the boat
spending her time in Florida and southern Caribbean waters. FYI,
Bottom Dave will do a P424 here for under a thousand dollars, and
he’s been doing this for decades.

Good luck,

Tor

Charlie, I had a crack running down the center of my keel and the PO poured
a half a ton of concrete on top of dirty glass on the inside. On the
outside, under the boat, after cutting a large v down the center of the
keel from the lead to about 6″ from the back end, I laid layer after layer
of matte until flush with the old surface then at least 4 or 5 more of
biaxil and cloth on top of that all the way out and up the sides about 3″
or 4″. That was about 15 layers on the outside. All with west system epoxy.
After the nightmare of removing the concrete and all the bad epoxy and oils
from the inside of the sump (Oh yeah, that was a nightmare of biblical
proportions, see it here …
http://pagetwo88.blogspot.com/2014/02/the-dirty-deep-down.html (you can
scroll around the posts and see more of the fix) I added
3 or 4 more heavy bi axial layers on the bottom inside after filling with
more small layers of matte going up the sides about 3″ or 4″ I did not
carry on and add extra layers to the sides of the sump, although it entered
my mind as I saw how much thinner it was there. I built a shelf about 8″
off the bottom (where the concrete used to come to) and when I splashed the
boat that shelf was jammed wicked tight, I had a hell of a time getting it
out to re-cut because the pressure had squeezed those sides in at least a
1/2″
Have fun,
Ken

On Mon, Feb 9, 2015 at 8:26 PM, cstewart via maillist <
> wrote:

We had our pow-wow this afternoon and have pretty much decided that we
will go ahead and blast through the barrier coats to the epoxy coat and put
on new barrier coats then bottom paint. Will know more tomorrow after a
test blast. They recommend the Sea Hawk barrier coat and say that 2-3
coats will do it.
Tor, I reviewed the article you wrote about the split keel you had, and
did an inspection. Though we do not have a split or crack, I can see that
the glass matte of the keel has been worn down so that the matte looks like
it has been cut. After blasting, I have a glass guy that is going to cut a
deep V in the keel bottom and re-glass and epoxy it and then put some new
matte and glass on the bottom to replace what has been sanded off by
groundings over the years. Though we have had no problems with any
leaking, I will feel much better having the bottom of the keel replaced and
strengthened. Has anyone added glass matte to the inside walls of the
sump? That seems awfully thin???
Charlie Stewart
OneEighty #54

---

"People cannot discover new lands until they have the courage to lose
sight of the shore."
Andre Gide 1869-1951

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Charlie,

Sounds like what Ken did is even better than Silverheels’ keel
reinforcement. I wish we had thought of going up the sides,
although they’re not nearly so prone to impact as the bottom.

One of my first and smarter upgrades on Silverheels was to
thoroughly clean the bilge sump and then paint it white. (Did
that on my previous cruiser, too.) You tend to keep it clean
after that, can instantly find fasteners & tools that inevitably
fall down there over time, and best of all you’ll quickly spot
any new oil or water leaks. Oh, and the boat won’t stink of foul
bilge water anymore. As long as you’re in there messing around
anyway, you might as well finish the job right. You’ll be glad
you did.

Tor

Hi Tor,

What paint did you use on your bilge. That’s on my “get to it eventually” list.

Unfortunately on the 422 the sump is inaccessible. The water tank is in under the floor in the main cabin and has a deep section that dips into the sump. The tank is a separate structure that sits in the sump but stands off the sides by a few inches so still room for stuff to fall in but no way to see it or get to it. Kind of like a black hole.

Skip, if I’m picturing that sump of the 422 accurately, I definitely would want to lift that tank out if possible and see what has accumulated in that black hole over the years. Where are your bilge pumps?

I’m with Tor on the bilges, they are someplace you should be very familiar with. All my past boats (which were wood) the first line of business was to clean out bilges thoroughly with all limber holes (water passages between floor timbers) reamed clean and red lead painted. Actually, my first full keel boat had varnished bilges, yup right down to the oak keelson. The PO had stored fruits and veggies down there (and beer) as there was no fridge.

For painting your bilges, my opinion, any decent oil or polyurethane will be fine as long as your very thorough with the cleaning. There are some specially formulated bilge paints if you want to pay the extra.

Ken

Oh if only I could. I wasn’t kidding when I said that area is as inaccessible as a black hole. It might even exist in a parallel universe. The water tank as a mentioned is a separate structure (fiberglass) but it is shaped to conform to the hulls sides and sump and extends well under the floors both fore and aft and athwartships. It would require ripping out the floors and disassembling part of the cabinetwork to get it out.

Just forward of the engine there is about 3″ gap between the aft side of the tank and the aft end of the sump that I can look into. There is a similar gap between the tank and hull in most areas but less around the sides and it extends to within about 6″ of the bottom of the sump. I agree with bilge familiarization and have done so as much as possible but this one spot.

If I reach under the V-drive I can feed a flexible extension I made for my shop vac down into the hole and suck out whatever has fallen in. I pulled out an amazing collection of oily rags, screws, odd parts and miscellaneous trash the PO allowed to accumulate over 30 years. %$@$%@!!!! The bilge pump by the way goes down the same crack so needs to be small or narrow. Plan to use a Whale supersub pump which is long and skinny, augmented by two 4000 gph Rules for just in case. Rules are not my favorite for long term, everyday use but the big ones I think will be fine for being there if I need them.

I would say all in all this is the most annoying thing about the 422 vs the 424. On the plus side, the fuel tanks are 2 X 40 gallons, each under the settees and easily removable (which I did to clean out and weld a new section on the bottoms where pinhole leaks had developed). Also the water tank does make use of a large and otherwise wasted space.

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Hi Charlie,

Will see if I can dig it up. I don’t recall that the article gave a lot of specific recommendations other than it can create a nightmare mixing several different chemistries in attempting a bottom seal. Along the lines of one job with epoxy, a second with polyester or isophthalic resin, etc. can create a witches brew of incompatible chemicals.

I think the biggest nono is trying to get a polyester or iso resin to bond to old epoxy. Epoxy bonds pretty well to other resins but once the epoxy is cured other resins do not bond so well to the epoxy. This may be one of the things that leaves a lot of potential for returning blisters.

If I’m not mistaken the Sea Hawk is an epoxy? If so in my uncertified, non-technical, limited experience based opinion there should not be a problem with one brand epoxy reacting with another brand. All the ready to use epoxies are based on the exact same unmodified base epoxy resins made by Dow, Shell, etc. Companies like West Epoxy, MAP, etc buy the basic epoxy from Dow and add their own modifiers which effect cure time or strength vs flexibility, blush, etc.

One thing I’m pretty clear on, to get a new coating onto an old, existing coat you will have to get a good mechanical bond, so good sanding and surface prep are important. If new epoxy coats are applied before the previous coat is cured they will chemically bond but after a day or so that ability is gone.

Just for information and pardon me if I’m saying something you already know well, but epoxy curing is a chemical process called cross linking. Starts with a bunch of loose molecules of epoxy, add the curing agent to start the reaction and all the molecules start linking IE joining together to make one large matrix. That’s why it’s of great benefit to put on succeeding coats before the previous are totally cured.

Regards
Skip

Here’s a link to a series of articles about blisters: causes, repairs, failed repairs etc. I don’t necessarily agree with all this guy says and in several areas I think he is way, way over the top in his opinions. So take some of this with a grain of salt but there is some good information mixed in.

http://www.yachtsurvey.com/blisters.htm

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Charlie
when we got our boat, we had a bottom job done. All the gelcoat was ground off, and replaced with mat and isoester resin. As extra protection, I rolled on a couple coats of Interprotect 2000 before launch. Over the years, the Interprotect came off in sheets taking expensive ablative bottom paint with it. Interlux told me that the Interprotect would not stick to the new resin becauae the resin outgassed for a couple years. We finally, last year,had all the Interprotect removed, then redone as the resin was by then a decade old and quite cured.
Suggest that you talk to Interlux before using Interprotect if the keel repair is done with polyester resin and get a commitment that they will stand behind it.
Quent

Just to toss my two cents into the bilge. I used pigmented epoxy under the new (5 years ago) engine. If any oil or other fluids leak I can use solvents to clean that would strip paint. I like the idea of adding a few layers of cloth in the bottom to reinforce and then finishing off with pigmented epoxy. This will all have to wait till I retire one way or another.

Linus
Sumocean

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