How do I trace a leak?

[Athene V30]

I have a slight leak on my fin keel sloop that I cannot trace.

The boat is GRP. When I bought her last November the boat had been out of the water for some months but the survey showed no signs of osmosis / leaks etc. Since going into the water late in Feb I have had to clear out a few gallons a week.

Initially I thought it was the stern gland and have repacked this. The disposable nappy test at the point of exit has given a dry result! I have checked all sea cocks and they appear to be dry. It is not coming from the water tank.

The boat has an integral keel which is also the bilge (hence a few gallons is not a great problem) and there seems to be a slight drip at the back end of the keel a couple of inches above the bottom BUT I cannot trace where it is coming from? Any ideas how to trace and then fix?

Thank you in anticipation!

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[waterboy]

Have you tried the rudder post and tube? This is often the source of hard-to-detect leaks as when the boat is stationary, the top of the tube is above the water line. But when under way, the stern tends to squat lower consequently with the water line above the top of the tube and water leaking in past a defective seal.

Alternatively, have you tried tasting the water? It could be fresh water with a leak somewhere in the plumbing.

<hr width=100% size=1>I never make the same mistake twice. I always make new ones.

 

[Athene V30]

There is no obvious trickle from the stern. The engine compartment is quite oily so water shows up well!

I did try tasting the water, slightly salty, which made me check the water tank as I thought sea water would be more salty! Will trace the water pipe at the weekend.

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[oldsaltoz]

G'day Peter,

Most leaks can be isolated with a some talk or chalk powder, sprinkle at both ends if the keel well, this will indicate what end to investigate, then around all thru hull fittings including stern tube and rudder tube, also under the anchor locker if fitted.

Some food colouring in the water tank will highlight any leaks.

Post back when you have identified the point of entry and we can work on how to fix it.

Good luck, andavagoodweekend........



Old Salt Oz /forums/images/icons/cool.gif Growing old is unavoidable. However, growing up is still optional.

 

[tome]

I don't know your boat, but is the mast keel-stepped? If so, you may well get some water down the mast.

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[tony_brighton]

Has it been raining? What about leaking windows, stanchions etc?

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[AndrewB]

Two additional suggestions of places where I have found 'mysterious' leaks:

... from the chainplates, flexing in use and sometimes underwater, fine when stationary.

... from the engine cooling system.

That having been said, the commonest source of leaks on my yacht has been from weeps in the pressurised water system. The taste test isn't that reliable with small amounts of water, as the bilge tends to be salty.

PS You seem to be pointing us at the keel. Some older bilge keel yachts, with the keels attached with a single line of bolts, are notoriously prone to leaking, but it is comparatively rare in fin keelers. A hull/keel joint leak will generally be MUCH worse when the yacht is in action than lying in the marina.

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