Due to the length of the tank and the fact that it is aluminum, I would not use tabs welded to the tank to bolt or screw through the stringers. The boat will flex during operation and it is possible that the tabs will be subject to work hardening then cracking, ie leaks
It would be better to install straps over the tank and bolt these to the stringers to negate these tab stress concentrations
You require " a non metallic, non-moisture absorbent and non-abrasive material, neoprene, Teflon or high density plastic permanently bonded to the bottom of the tank where it contacts the bottom of the tank supports . (ABYC) This goes for the straps that you have to hold it in place. Permanently bonded by an impermeable, non-hydroscopic adhesive
A polyurethane adhesive, preferably marine grade.
You require 1/4 inch of space between the bottom of the tank and the bottom of the surface which is this case is the hull floor
24.10.9 ABYC: Metal tanks shall be installed where they cannot be reached by normal accumulation of bilge water in the static floating position
Filler hose must be attached by two clamps, minimum width 1/2 inch. Ensure that the clamps are stainless which is common but often the worm screw is not. The screw can corrode over time so buy the ALL stainless marine type
Draw and vent lines, Single hose clamp are allowed but for hoses less than 7/16 the minimum band width is 1/4 inch and 7/16 through 13/16, minimum band width is 5/16
It is a very good idea to buy the exact sized clamp, ie a 1/2 inch band width will not really work on a very small hose as the screw assemblies natural bend is too large
Minimum vent diameter is 7/16 and THE SAME ON THE TANK
Use only stainless fittings OR aluminum fittings, and for screws to hold the sender in place and the hose fittings. NEVER COPPER OR BRASS
You will need baffles in the tank, perhaps 3 of them full height with openings at the top and the bottom. The open area of the baffles should not exceed 30 percent.
You require a draw tube, ie you cannot hook the fuel line into a bottom fitting of a tank. If there was a fire, and the hose burned, the fuel would gravity feed into the fire. Also, ABYC requires an antisiphon fitting to reduce this risk. Aluminum fitted draw tubes are available at many marine supply stores
All fittings have to be at the top of the tank including the fill. You might have some difficulty with your layout.
There are new filler vent requirements that do not permit open venting of the tank to atmosphere. I believe that the Perko website has information on this
Due to the length of the tank, I would recommend two vents, one at the front and the back. They can be common. This is due to the fact that say the vent is at the front but due to boat loading the bow is down, vapor trapped in the aft section of the tank can push fuel up the vent into atmosphere. You can put two top fittings in, tie them together then take on line up to the vent to reduce this risk
Rubber hose, filler or fuel lines, can allow vapor to permeate through it which in a vented automotive application, is not a problem. For marine applications, purchase only
marine rated hose.
The filler neck, and tank require grounding "so that its resistance to the boats ground is less than one ohm"
Not sure about this to a fibreglass boat but perhaps it has to do with static electricity.
Several years ago, a fellow was filling a plastic 5 gallon gas tank in the back of his pickup and the static electricity ignited the gasoline vapor. Now the rules require the plastic tanks be placed on the ground before filling.
