Tracing a deck leak

[superheat6k]

I have a small but persistent leak which appears in the aft corner of the port berth in the fwd cabin. The bulkhead separates from a large locker running right across the boat, this locker stays dry. I can't see where this water tracks along from. Over the Winter ~2 pints of water have collected in the locker below the berth, and this had previously saturated the mattress and rotted the cover, so I now leave the mattress propped up off the berth.

There is nowhere obvious as to the leak's source. I have thought about sealing the cabin and partially pressurising it with a bouncy castle fan, then soaking the deck area above with soapy water, the idea being that bubbles would form at the water entry point, but could I cause damage using fan pressure.

Any other ideas ?

 

[pcatterall]

This is almost as 'good' as anchor threads.

One method I have used on dry days is to soak or run water over different sections of the deck. Once I find the general area of the leak I repeat but just wetting a smaller area.
Lots of other tricks which I will leave to others!!

 

[starfire]

I have a small but persistent leak which appears in the aft corner of the port berth in the fwd cabin. The bulkhead separates from a large locker running right across the boat, this locker stays dry. I can't see where this water tracks along from. Over the Winter ~2 pints of water have collected in the locker below the berth, and this had previously saturated the mattress and rotted the cover, so I now leave the mattress propped up off the berth.

There is nowhere obvious as to the leak's source. I have thought about sealing the cabin and partially pressurising it with a bouncy castle fan, then soaking the deck area above with soapy water, the idea being that bubbles would form at the water entry point, but could I cause damage using fan pressure.

Any other ideas ?

Useful sometimes to sprinkle the area with talcum power, then look for tracks..

 

[ghostlymoron]

Persistent leaks are extremely annoying and can cause serious damage. Finding them is difficult as water can track unbelievable distances. Running a hose above and around the deck above the leak can reveal the entry point and as has been said, talc is helpful sometimes. Your pressurising idea sounds promising and cant do any harm.
My money's on a leaky deck fitting. You could re-bed any within a metre radius of the exit point.

 

[Porthandbuoy]

Make a little dam of play dough or blu-tac around your deck fitting. Fill each with water in turn, and see which one empties.

Any windows or portlights in that area? Try Captain Tolley's Creeping Crack Cure (I suspect it's just diluted PVA). Run it around the window seal on the outside for a temporary fix until you get round to rebedding the window.

If it's your gunwales that are leaking into the hull/deck joint you've a bigger problem.

 

[Deleted member 36384]

.... Any windows or portlights in that area? Try Captain Tolley's Creeping Crack Cure (I suspect it's just diluted PVA). Run it around the window seal on the outside for a temporary fix until you get round to rebedding the window. ....

Good advice regarding the window but beware if one has windows mounted in channel sections and sealed with O ring type seals. The water was getting between the window glass to frame seal and filling up the channel, which eventually corroded through. The seals between the glass and channel were sound looking but had become stiff due to age and lost their resilience. Despite applying the captain's cure even to this seal it must have failed due to the alloy expansion in warm weather, perhaps because the contact area between the O ring shaped seal between glass and aluminium.

 

[Capt. Clueless]

Water is such a crafty fellow, who will come through a tiny apperture somewhere and eventually head south some way from the initial entry point. That I have discovered. I was checking for a leak, and found it about a meter from where it was making it's appearance.

 

[Lon nan Gruagach]

Blowing air back out might take exceptionally long to have an effect and might not work at all. Its very important to know how long it takes the water to get from outside to inside, armed with that you can adjust your investigation. So, wait till its all definitely dry, drench the outside and time how long it takes to get in.
If you can reliably get a situation where the inside is wet and the outside is dry then you could use a cable locator to follow the path back out (treat the water as a wire). Also along those lines, if you use salt water you might get some mileage with measuring resistance from inside to spot locations on a wet outside.
Water can even go uphill just to get into your cabin, ask any builder about leaky flat roofs.

 

[neil_s]

In my continuing efforts to fix the leak coming through one of the saloon light fittings I have this year rebedded the handrails and completely dismantled and re-built the hatch garage. This is the not-so-good side of moulded-in headliners. Maybe the wet patch on the settee will go away? You just have to keep trying!
Salt or fresh water? might give you a clue as to where it's getting in.
If it's fresh, covering areas of deck with a small piece of tarpaulin also might help to find the culprit.