Water tank pickup problem

[GILow]

Hello Cruisers,

I recently traced the horrible smell in my boat to a pair of keel water tanks that were no longer in use.

The tanks are aluminium, and are REALLY hard to get to. Removing/servicing them would involve removing a 400kg engine and gearbox, plus the entire electrical closet. So, the plan is to flush them out thoroughly, treat them with a bit of bleach, and periodically repeat the process. I can work with that.

BUT, I am having all kinds of trouble pumping them out. The pickup hoses are made from some kind of (originally) flexible hose, around 25mm OD, looks a bit like the sort of hose that would feed water to a washing machine. These hoses enter the tanks from the top through an aluminium tube that sits about 20mm proud of the tank, and is about 30mm in diameter. The end result is that there is a small gap around the pickup hose, enough to "rattle" the hose around, but not quite enough to poke through anything other than a very fine pickup tube/hose. Now the pickup tubes themselves seem to pickup MUCH less than half the contents of the tank. So sucking out the first 30 litres is easy enough, but the remaining 60 litres takes forevever as it has to come out through a tiny <10mm tube squeezed down beside the original pickups.

The original pickup hoses have gone rock hard, and when I tried to pull them out they are utterly unyielding. The filler tubes enter through a separate fitting at the top of the tank, and although flexible and in good condition, each has a right angled attachment at the top of the tank that makes feeding any kind of pickup tube into them nearly impossible.

So, my question is (after all that background), does anyone have an idea of why these old pickup hoses are not pulling out? I wonder if perhaps the hoses have curved upwards inside the tanks, accounting for the hopeless pickup percentage, or is there some kind of standard fitting that might be expected in a boat of this era (fitted out in the early to mid 80's) that would account for the hoses refusing to budge.

I have not put a LOT of pull on the hoses yet, for fear of breaking something, so they may yield if I really get some grip and leverage on them, but this sort of approach may break something.

Any ideas?

Matt

[GILow]

If anyone stumbles on this thread looking at a similar problem, the explanation was that the pickup tubes were actually attached to bladder tanks inside the original aluminium tanks.