What kind of tubing should I use for my fuel lines ?

a. The view of the aft batteries shows our fuel plumbing. I have 5 fuel tanks as the area under the wheelhouse sole is divided up by “floors” (bulkheads to reinforce the area – which may be overkill). There is a fuel supply manifold with 5 shutoff valves and a fuel return manifold with 5 valves. All tubing is 3/8″ stainless with Swagelok connections. This is expensive and was time consuming but I didn’t want to have copper tubing (accelerates fuel gumming) or rubber tubing. Fuel was my specialty when I worked at Shell Oil. The other black tubular items are the heavy gauge wires to the inverter and breaker panel, also from the fwd batteries and the engine alternator batteriesunderpilothouse.jpg . David Salter (s/v #050, Opportunity)