Keel crack and osmosis

[Troppo]

When I first bought Windchaser in 2012 and put her up on the slip, I was expecting the underwater sections to be in quite good condition as a survey had been done only 12 months previous and given the all-clear. Unfortunately I found the rudder delaminating, an old crack under the keel allowing water to seep slowly into the bilge and what looked suspiciously like old repairs to osmosis. A year ago I did her second slipping and osmosis lumps were appearing. Also, just before she went back in the water, I noticed a stain on the concrete under the keel and realised that in a different spot to the crack right under in the keel I had repaired the first time, appeared to be another small crack that was leaking the tiniest drip. This year I started work on the osmosis and searched for that other crack which had vanished.

After some poking around with a chisel, I found a tiny bit of moisture was accumulating at a point but I could not see any crack. Today, after several days on the slip, I did some more serious poking around. There was no drip forming but the section of fiberglass I had exposed was staying moist, not drying. I got my manual drill and started cleaning away some of the fiberglass, looking for some kind of crack that was dirty. Saw nothing. Bit more weeping so I applied my usual strategy - if something appears to be broken, hit it hard to make sure it is. The drill bit went in about an inch before it came to a void.

Pulled the drill bit out and water of some sort cascaded out, a litre or so.


Here's what the osmosis repairs look like so far. Note that the other side only has a few blisters, not like this side.

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There's a joke about drilling a hole in the bottom of your boat to let the water out. Well, I have drilled that hole and it is in what I assumed was the solid section of the ballast, and you can see what happened.

After jumping out the way when the water started coming out, I eventually raced to my car and got my camera water was still coming out.

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So at this point, I am trying to work out exactly what is going on with the problem under the keel. And hoping it will dry so I can epoxy it for going back into the water.

troppo

[woodsy]

Bugger is the NICE reply.

[woodsy]

I poked around when I bought mine & found a few small blisters. Stabbed one & got THE smell. Turned a blind eye & wondering if there is a can of worms in there.

[Troppo]

When I went down to Windchaser this morning I expected the little ol' hole I drilled in the keel last night and water stuff poured out to be drying out. Wrong.

After standing all night, still dripping, but it's glug.

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Not only was it still dripping this morning but instead of it being some kind of watery liquid with chemical smell, it was just stinking chemical liquid and oily looking. Ohh, nasty.

By lunch time it was still dripping. Taped a clean cup underneath and after lunch I had almost a full cup of coffee. There is a layer of some clearer fluid right at the bottom. Maybe that's the cream. Wasn't feeling thirsty so didn't drink it.

Since it continues to drip, I am glad I still have some days left before going back in because it ain't gunna glue up the way it is being so wet.

Glug.

keel problem 2.jpg (315.86 KiB) Viewed 5832 times

[Troppo]

The osmosis repair is going well. Here's what I am doing even though I suspect you can find better examples elsewhere.

First I punctured the blisters with a screwdriver and tap from the hammer. I wore protective eyewear as it can squirt out. Then ground out, wearing more protective gear for ears and breathing and actually had on one of those disposable hazard overalls so did not get fiberglass dust on my skin. Power washed it several times over a few days. Once used detergent as well. Seemed to clean up and dry out well.

Ground out and power washed.

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Painted epoxy on the craters, cut fiberglass cloth and put it on, more epoxy on top to wet out the cloth. Some craters had many many layers. Two of us worked on this. One cutting the cloth to size and putting in place and the other dabbing on the epoxy. Easier than one person with epoxy-sticky gloved hands trying to handle scissors and fiberglass cloth.

Filling with cloth and epoxy

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Once the epoxy with fiberglass cloth had gone tacky, mixed up some powder in epoxy, good for underwater sections (a Botcote product). Hopefully got the levels near enough because tomorrow I will sand it and don't want to have to do too much. But also don't want to fill in dents too much either.

The blue bit of stuff stuck on one crater is peelply. It simply goes on like a dressing on a wound, does not stick to the epoxy but helps hold it in place. The thickness of brown epoxy was a bit deeper than others so I must not have put as much cloth in the crater as I could have and the batch of epoxy that I mixed (did small batches as takes ages with doing the filling and a big batch would go off) was a little soft so it started to sag. The peelply will hold it in place and when pulled off has a finish that can be painted without sanding. I could have done all the craters with this stuff and if I was good could get it so I would not have needed to sand many of them into shape at all. But tomorrow I sand.

Epoxy with powder filler suitable for underwater

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[Shaun]

That Peelply stuff looks interesting.

Complete mystery to me, as to where the black liquid is coming from, must be a void somewhere in the ballast, I wonder if that's the colour water goes when it contacts lead.

[Troppo]

Hey Shaun, I used peelply a lot when I repaired my rudder. Since I had stripped back the rudder to the ply I had a lot of epoxying to do and I found the peelply especially useful.

With the liquid, I know the osmosis fluid is dark from the chemicals leached from the resins so I suspect this stuff is similar. Certainly the lead would add to the cocktail mixture.

troppo

[Phillip]

Troppo,

Maybe its time to drill another hole and flush your keel out with fresh water?

[Troppo]

Sounds like you are knowledgeable about this, Phillip. What do you suggest?

troppo

[RodM]

A few thoughts...
Have you stuck a wire into the void to get some idea of its shape - either an actual hole or more of a fissure?
If there is a clearly defined void then a second hole will be useful - stick a tube/straw in so it sits near the top of the void, pump your filler in the other hole so air is expelled from the straw, then when the straw clogs up, pull it out and let the filler seal the second hole from inside... This is an idea, not something I've done!
Could it be from the keel water tank? Is it worthwhile opening the tank inspection ports seeing if there's any info gained from looking down from on top?
Good luck with it...
Rod