Originally Posted by David M
Thanks. That is some very helpful information.
I have learned that what I want to do is not approved by ABYC. Gasoline tanks cannot have drains. All fittings must be at the top of the tank according to the standards. What this means that there are no gasoline fuel tanks that have been tested and certified that have a drain, they would not be legal. The rules also require all tanks to be certified to certain pressure, shock and fire resistance standards. Therefore a custom made tank would never fly...the designs all have to be lab tested.
This is where I found my info: New Boatbuilders Home Page - Fuel Systems
I like your idea of two separate fuel systems where you select which fuel tank you want to draw from. It seems to be okay with the CFR's and ABYC. At least I don't see anything prohibiting this setup. I could probably put a Y-valve in the pour hose so that after one tank is full I could switch the valve over to fill the other tank. A Y-valve on the pour hose would mean I never have to take the fuel pump
nozzle below deck, eliminating a potential source for a spill and possible fire.
So does this seem safe and legal with respect to the CFR's and according to the ABYC's guidelines?
You are best to avoid any installation
that requires you to take a fuel nozzle below the deck. Safety
and convenience are powerful incentives here.
A few considerations regarding the Y valve for the fuel fill... All boats I have seen with two fuel tanks have a separate deck fill and dedicated fill line for each tank. When fueling, you want to minimize the inconveniences associated with the process. Having to go below deck to turn a Y valve while at a fuel dock
is something you might consider avoiding. The prospect of an accident
occurring while opening the hatch
, stepping in and out of the engine compartment, accessing the valve, etc. can be high during the presence of wind
or a wake. Imagine performing this during a small craft advisory. Also, you want to minimize the number of connections between the deck fill and the tank. More points of connectivity invites a higher degree of risk for leaks
, compromises in the integrity of the hose, and more maintenance
in general. This is not an area you can afford to have fuel leaks
. And lastly, marine grade fill hoses are INCREDIBLY difficult to work with. They are very rigid and do not tolerate bends well at all. Just a few things to think about...
And to answer your question about the Y valve being safe and legal. The safety
issue is addressed above. But as far as legality is concerned, I doubt it will be compliant. I performed a rudimentary search for Y valve rated for marine fuel fill lines, and had no success finding anything for that purpose. If it was legal, most marine supply houses would carry them. There are plenty of Y valves for switching between tanks, but none for fuel fills.
One option you might consider is an above-the-deck fuel transfer tank. It is the least costly and quite easy to install. It can be filled and left there. You can create a closed system with a pump plumbed to your existing tank. When your existing tank is depleted enough, simply activate a fuel transfer pump and the fuel from the transfer tank can make its way to your existing tank. The nice part about this arrangement is your ability to remove and replace your new tank with minimal effort and minimal impact on your boat. If you find yourself not needed it, you can simply remove it and not worry about dealing with the holes you made in your hull
for the deck fill and vent. You might want to research
requirements for fuel transfer tanks, but I don't believe they need to meet USCG (CFR) requirements for marine fuel tanks. The transfer tank will also be vented, so there would be no need to run a vent line and penetrate your hull
Hope this helps.