I am restoring a Formula 255 Performance Cruiser and got in a discussion on fuel lines.
Looked for copper lines and could only find steel locally then looked at the Coast Guard Regs...

from cfr 33 § 183.558 Hoses and connections. (a) Each hose used between the fuel pump and the carburetor must be ‘‘USCG Type A1’’ hose.

Comments? What are you using?

any hose used below decks is supposed to be USCG A-1.That is hose ...typically between the pump and carb is hardline

I would not use copper, see it in lots of old boats. reacts(green varnish on fittings) to gas and does not have long fatigue life unless properly supported. would run S/S or steel line with short sections of hose. see lot of changes in the B-1 hose, mfgr's change about 6months to the year. the inner liner have collapsed if not the whole hose from verying levels of ethanol(5-30%), get newest hose. have had new B-1 low perm(EPA) hose collapse.