Draining keels

[jimbarnebee]

Our keels had some water in them so we drilled a couple of holes to drain them out while we're on the hard doing some other repairs...
The port keel seems fine but the starboard keel is still draining after a few days and smells....
does anyone have any insight as to why water draining from a catamaran keel would smell bad? What might that indicate?

[JC Reefer]

Rot would be my guess. If water is slowly weeping out then it’s probably made it’s way into some tight spaces.

[JPA Cate]

I'm not an expert, here, and you might post a thread in the multihull forum, also, asking how to remediate it. What you have is a structural problem, and it does require repair. You found bad news, some of the laminate is very full of water to still be draining, but really, neither keel is in good shape, if they needed draining.

Sorry,

Ann

[Cheechako]

Uh, it would help to know the type of boat. Swing keels? daggerboards? glass moulded keels?

[Palarran]

I've had the same problem and don't start to freak out. Lots of cats have this issue. Mine is solid fiberglass with some foam sheets in it. The water also smells like 1 year old stank sea water. The real problem is that instead of being filled with air and pushing the boat up, it's heavy and slowing her down.

We drilled a hole in the flat portion of the rear part of the keel and installed Maleron drains two years ago. At the same time I had a small fiberglass crack sealed on the starboard keel. That one had maybe a half gallon of water in it after a year. The port, well, she was a gusher when drained. We took our dingy pump and pumped up the void, checked for leaks with soap bubbles, and found one. As we only had 24 hours before launch, I used that West Marine epoxy to seal it and added some anti-foul. I guess in a year it will be clear whether that fixed it.

On the next haul out I'll do it earlier and really find out if there are any more pin holes then repair more permanently.

[GordMay]

If the liquid smells like vinegar, likely there is saturation, and hydrolysis present. Not good.

[JPA Cate]

I had to Google "hydrolosis".

Here's the Brittanica's definition:

Hydrolysis, in chemistry and physiology, a double decomposition reaction with water as one of the reactants. Thus, if a compound is represented by the formula AB in which A and B are atoms or groups and water is represented by the formula HOH, the hydrolysis reaction may be represented by the reversible chemical equation AB + HOH ⇌ AH + BOH. The reactants other than water, and the products of hydrolysis, may be neutral molecules—as in most hydrolyses involving organic compounds—or ionic molecules, as in hydrolyses of salts, acids, and bases.

[GordMay]

Osmosis on boats
➥ https://www.almerimarmarine.com/osmosis.html

BLISTERS & LAMINATE HYDROLYSIS
➥ https://fiberglassatlanta.com/webdocs/blisters.pdf

[jimbarnebee]

Palarran - what was the exact kind of drain you put in? we have a cat, and one of the keels seems to have drained and been fine- the other we have a concern that the bilge is somehow leaking down into the keel so we're trying to track that down now

[Palarran]

This one:
https://www.defender.com/product.jsp?id=2051942

Do you have water in your bilge? The way my cat is designed, and I think many, is that there is a trunk which the keel fits into. That trunk is sealed from the keel so if water gets into the keel, it doesn't come into the boat. Unlike other Fountaine Pajots though, my keel is fully glassed into the trunk so it's not as "sacrificial" as all their new designs.