Help Installing Forward Hatch Auxillary Tank

[abbeydorney]

Need help in setting up an 18 gal auxillary tank in a forward hatch. It's a little bit unique as the hull is 20 converted seafari to a CC with doghouse and the hatch is longer front to back. I have found some good general information for tank install, but wondering if I could get some help with mounting and in particular venting the tank. I have attached a pic of the tank just set in the compartment. The main tank is very accessible aft of a doghouse. Appreciate any help, Thanks, John

[Xcomunic8d]

Welcome to CSC!

Can you give us more pics? I can’t tell much from that other than you have space for a tank. Now routing it will be the fun. Ps don’t forget the vent must run downhill or uphill depending on viewpoint to prevent vapor locks (filling and emptying issues). Filling and pickup are less an issue in my setup.

Do you have access around those bulkheads to route lines etc?
Put your pick up tube towards the rear. When on plane that’s where your last bits of fuel will be. My 2 tanks are vented and filled on stern transom cap. I have each running to an individual fuel water separator With a ball valve then in-line together to an electric assist fuel pump on to outboard. I have a friend with a boat that fills and vents off the starboard side of hull. Not as pretty but I imagine considerably cheaper and easier hose routing.

In theory the tanks should evenly empty as it pulls a vacuum and pressure equalizes. I also am keeping my fuel pickup, fill, and vent lines the same length.

[abbeydorney]

Thanks so much, first post but a long time fan of this site, its an amazing resource. Apologize for my delay in response -- the boat and I are a few thousand mile apart right now and was trying to get my brother to get a few pics. When he opened up the access hatch for the main tank - he could see that the forward compartment we had set the tank in is just a lightweight tub supported only by its rim, with quite a bit of area between its floor and the hull, so we are taking a moment to consider if its worth doing it the right way with proper bracing etc, or just stick with jerry jugs etc. I liked your idea of mounting fill and vent aft and that would put fill and vent lines for both tanks relatively close. Thanks for taking the time to offer some advice and will get more detailed pics if we move forward - John