Originally Posted by Bilge Rat
I'd imagine some sort of funnel would do the trick
Using a funnel is all very well but sometimes there isn't room to stick in a funnel and even if you could, pouring from a regular 25 litre tank would be difficult without a dedicated spout thingy attached (like you get with some jerry cans). Those Jiggle syphons are a good idea but probably a little slow for filling up at sea?
I will probably go for the Plastimo tank that is shaped more like a jerry can, then I get the best of both worlds!