where does bilge water come from in a plastic boat?

[futtock]

I can understand a wooden boat taking in water and needing the bilges pumped but why do we get water in grp boats? My boat seems to be getting more water in the bilges than usual - although it's still not enough to worry about. It's salt - I've tasted it. None of my sea cocks are leaking. The engine cooling water and exhaust don't seem to be the problem. As far as I can see that leaves only the stuffing box. I've refilled the greaser and pumped some more grease in so I'll see if that works.

As I said the volume in a week is not enough to worry about - but in general if the stern gland isn't leaking why do we get bilge water in grp boats?

Often depends on what kind of hull you have. There are countless places it can get in, skin fittings, leaks from the deck, windows just to mention a few but one that often gets overlooked is the temperature difference of the hull and a saturated air temperature. If it is very humid condensation can form and drip down the inside of the hull and find its way to the bilge. This can often be the small eggcup full you find.

 

[futtock]

Could be condensation running down the inside of the hull.

 

[Skysail]

A 10 year old boat had a very small hole drilled through the hull close to the waterline - it had been there from new. The owner suspected it was a pilot hole for a skin fitting that had eventually been located elsewhere. Hard to find and easy to fix.....

 

[greenalien]

The skeg-hung rudder on my boat is supported by a heel plate, which is secured by a long stainless rod that passes right through the skeg, and has a large nut and washer in the bilge to secure it in place. Regardless of how well it is initially installed, with loads of underwater sealant, after 7 -8 years use the sealant hardens, a little side-play develops in the heel plate and water starts to leak in. Not much, but a gentle hint that the rudder needs to be dropped and resealed at the next haul-out.