Geoff, I will have to come back to most of your questions in May after I have picked the boat up again in Scotland to bring it home to Norway. Only the following I know for sure now: - The daytank is indeed a Vetus tank. Plastic (polypropylene) is also the material of choice of Pat Manley (Author of "Diesels afloat") . - All pipes enter or leave both the main and the day tank through the top cover, including the return pipe to the main tank. (So I think that it is gravity, helped with the (low) pressure in the fuel system which makes the clean excess fuel flow back to the main tank). - The day tank has a vent without a 'swan neck' but with a valve. (I have not opened that valve yet. I believe that it is to be opened only when the day tank has to be topped up after installation or after having run out of fuel. Obviously there should be as little air as possible trapped in the daytank.) Regarding self priming: This should be easy to test before installing the pump. Connect a pipe and a battery and see if it can suck fuel out of a bucket. The setup on my boat has one issue, which is that the facet pump is noisy. I believe that this is because of the copper piping which is directly attached to the pump. The good thing of this is that I can hear that the pump works. I am planning to insert a bit of rubber pipe on both sides of the pump. That will probably bring down the noise level. If anybody knows where I can find fire-proof rubber pipes, I would be interested to hear. Herman.