BLUEMOMENT

Getting the boat ready for the water again, and one of the jobs I usually do is drain a little off the diesel tank.
There's a drain plug, but its hopelessly in accessible, so the best I can do is drain some out into the bilge.
There's almost always some gunk comes out. Its often black, and there's a some water as a result of condensation too.

This year I thought there must be a better way.

I got a plastic bottle, the strongest one I could find, with thick walls. Took the top off and drilled two holes into it.
Found some plastic tubing about a metre long and about 5mm diameter. Its clear see though.

Two pieces into the bottle screw top, a short one about 250mm long, and only just through the top, and the other long piece, right to the bottom.

Took the filler cap off the tank, inserted the long plastic tube to the bottom of the tank, and started sucking on the short straw. After decompressing the bottle a bit, the diesel started to come up, and the gunk with it.
I drew off about half a litre along with the gunk until it ran clear and no more rummaging the long tube about the tank bottom found any more bad stuff.
Then I was able to dispose of the gunky diesel without having it in the bilge.
A far better solution, and I know I got it all out.

I do similar with a hose and primer pump. The end of the hose is lead-weighted to hit the gunk. Usually very little harvested and I can let the liquid settle and pour the good stuff back through a filter paper.
As I said elsewhere, I can judge if gunk has got into the system or the filters are getting blocked by the rate of spillback when I hand-prime using the lift pump - I can hear it pee-ing into the tank....or not.