Techniques for finding topsides leaks?

[mogmog2]

We have a couple of irritating leaks in the cabin. I spread clean newspaper around, where I could, to indicate where there are drips. I know that the exit point can be very different from the ingress point, but it gives something to go on.
There are also a couple of small wet areas elsewhere and I felt around on the underside of the moulding but didn't feel any wetness, but then it hadn't been raining for a while.

I've also bought some fluorescein dye to see if that helps, with a UV lamp.

Anyone got any other tips for tracing leaks.
Thanks

 

[[70521]]

Talcum powder.

 

[ANDY_W]

When using newspaper, if the leak is of short duration, it may dry out before you next check it and leave no trace.
If circumstances permit, try using talcum powder. Even if the moisture dries out, the pattern of disturbance caused will still remain.

 

[VicS]

We have a couple of irritating leaks in the cabin. I spread clean newspaper around, where I could, to indicate where there are drips. I know that the exit point can be very different from the ingress point, but it gives something to go on.
There are also a couple of small wet areas elsewhere and I felt around on the underside of the moulding but didn't feel any wetness, but then it hadn't been raining for a while.

I've also bought some fluorescein dye to see if that helps, with a UV lamp.

Anyone got any other tips for tracing leaks.
Thanks

Blue paper towels ( like the blue elephant bog rolls you see in garages and workshops) show up water ingress well because they become a darker colour when wet. Much better than newspaper.
Make sure fluorescein solutions stay slightly alkaline ( a trace of caustic soda or washing soda) as it does not fluoresce if it becomes acid.

Blue elephant bog rolls like these

 

[Spirit (of Glenans)]

First I must give rein to my inner pedant; I feel you are more likely to be referring to deck leaks, as boats' topsides rarely leak, being the above-water sides of the hull, on this side of the pond, anyway. .
Rather than waiting for rain to enter and wet some paper or talc it might be better to be more proactive; isolate one deck fitting at a time, using putty or similar to create a dam around it, pour in some water and then look for a result with your favoured detection material.
If your boat is constructed in such a way that the through-deck fixings are fairly easily accessible, you can accelerate your search by wetting each fitting in turn and gently touching the ends of the bolts with dry (or talc-dusted) fingers.
The most likely suspects are usually stanchion and pulpit bases. Start at the lowest point and work uphill.

 

[chubby]

I am wondering if we get different rain in the winter????

In the summer when on board in the rain there is a leak into the cabin which irritatingly gets onto bunk cushions!


So the winter`s job was to locate and fix! OK so a fairly dry winter but no sign of leak!


The proactive approach sounds good.


my wife's unusually helpful idea was to hope for dry weather and protect the cushion with a plastic backed picnic rug of which we have a surplus!

 

[[70521]]

I am wondering if we get different rain in the winter????

The rain in summer is warmer.

With the boat on the hard the stresses are different and that tiny gap might be compressed and therefor sealed.

 

[Graham376]

The most likely suspects are usually stanchion and pulpit bases. Start at the lowest point and work uphill.

All good advice but also check the taffrail/pushpit mounts, particularly if it has a heavy life raft attached.

 

[mogmog2]

Re pedantry, Is there a term for deck, cabin sides & roof? Bit of a mouthful, hence shortcut but as I typed it I had misgivings, but didn't have time to check ....

Thanks for the tip re keeping fluorescein alkaline.

Re being proactive, we had a hose session in the summer & determined which windows were leaking & applied Capt. Tolleys more in hope than expectation of success. One still definitely leaks but we were hoping to get away with it this winter as I've got a lot of other stuff on. We've just got back from a first pass at cleaning & draining the oily bilge water than had got absolutely everywhere & now will have a bit of an idea as to the general water routes.

Tip re blue roll is handy. Was thinking about ordering some so more inclined to now.

Chalk dust would do the same as talc? And easier to see - this stuff: https://www.toolstation.com/builders-chalk-225g/p72104

Oddly, the most obviously traumatised stanchion (lifted a bit) doesn't leak. Thoroughly hose tested.
Thanks for the tips. keep 'em coming...