rotting around my windows

[gail stubber]

hello, I am in need of information about a white substance which is oozing out of the join between my aluminium portholes and wooden hull. It is soft and moist when i pull it out but turns into a hard blob when left away from the boat.
if you know what it is and how to treat it - that would be wonderful information.

[rbgarr]

It's called poultice corrosion. When water is left in contact with aluminum and it doesn't dry there's a reaction that breaks down the aluminum and turns it to a sticky powder, as you've seen. Eventually it can lead to pinholes in the aluminum that in the case of fuel tanks and thin aluminum boats (left on moist, carpeted trailer bunks) can become leaks in the worst cases.

The seal between the wood cabin side and the aluminum port frames are probably 'cracked' a little (or perhaps a lot) and water from dew, rain and washing down doesn't dry out. You'd need to rebed the ports to prevent the problem, but it would recur most likely.