Warning; I am only going to very briefly cover the basics here. There is much much more! Contact ABYC and the Coast Guard to get the latest standards for fuel systems.

First a note about the reasons behind the fuel, electrical and ventilation standards. Why is all this stuff required?

The Federal fuel system standards apply to:

Boats with permanently installed inboard gasoline engines for:

Propulsion

Generators

Auxiliary Equipment

This does not apply to:

Outboards:

Portable Equipment

Having said that, that is, the fuel system regulations don't apply to outboard powered boats, don't take that too seriously. The industry tends to follow the ABYC standards, which are tougher than the Federal standards. ABYC fuel system standards apply to outboard powered boats with permanently installed fuel systems. If you ever get dragged into court, that's what the complainants attorney will ask you. "Do you meet ABYC standards"? So follow the Federal rules for inboards too, even if you're making an outboard powered boat, unless you intend to use only portable fuel tanks.

FUEL TANKS

I strongly recommend that anyone building boats with permanently installed gasoline tanks (or diesel) not build their own tanks. The reason is simple. You have to certify that whatever you put in this boat meets Federal Regulations. Fuel tanks have to meet a whole raft of rules, and unless you are setup to test them it's better to just buy them from someone who has already tested and certified the tank.

Here's a list of the tests that tanks have to meet.

The 2 ½ minute fire test: Under very specific conditions the tank has to survive a fire for 2 ½ minutes. The test setup for this is not cheap and only a few test labs have one and know how to perform the test.

Slosh Test:

Pressure Impulse Test:

Static Pressure Test:

If the tank can meet all of these tests then a label has to be put on the tank that says; "This tank has been tested under 33 CFR 183.580" which means it has passed the static pressure test.

Also, if you are planning to put the tank in the forward half of the boat it has to meet additional requirements. Tanks that don't meet those requirements have to have a label saying "Must be installed aft of the boat's half length."

Tanks also can not be integral with the hull. That means that the hull cannot form one side (or more ) of the tank. Tanks must be separate from the boat structure. Yes, Yes, we all know that some of the really big boat makers do this. Those are all diesel powered boats and this rule doesn't apply.

So, go buy a tank from a tank supplier.

Some other considerations. Basically there are two kinds of tanks commonly used in recreational boats, aluminum and plastic. Both have distinct advantages. Some people swear by aluminum, others swear at it. The same is true for plastic. I tend to lean to plastic. They don't corrode. But the choice is yours to make. Tanks are occasionally made out of other materials such as steel, stainless steel, monel and so forth. If you want to use other than aluminum or plastic, you will probably have to have the tank specially made.

If you really want to know about tanks call the American Boat and Yacht Council, (410-956-1050) and get a copy of the Fuel System Standards for Gasoline Powered Boats, or get the one for diesel, if that's your persuasion.

FUEL SYSTEMS:

Vents: Fuel tanks have to be vented. The vent itself has to either have a flame arrestor that can be cleaned, or be designed in a way to prevent a flame front from igniting the fumes in the vent. There are a lot of different brands of fuel vent fittings on the market that accomplish this.

This vent must not allow gasoline that might spill from the vent when someone overfills the tank, to spill into the boat. Catch 22. It is also illegal to spill fuel into the environment. So, think about it. There are several manufacturers that make combined fuel fill and vent fittings that do just that.

Fuel Pumps: Fuel pumps cannot leak into the boat, so if you have an engine that uses a mechanical fuel pump it has to be a double diaphragm pump or have some other means to keep the fuel from leaking into the boat

Electric fuel pumps can only operate when the engine is running.

Carburetors: Carburetors must be of a marine type. Again this is because you don't want fuel spilling into the boat. So, if the carburetor floods or the float sticks it must be designed to keep the excess fuel from flowing out of the top of the carburetor through a vent or other opening. Use only a marine type carburetor! Yes, they cost more. Yes, they look just like an automotive carburetor. But, they are different inside, and the difference can save your life.

Fuel Hose: When fuel hose is used it must be either USCG Type A1, USCG Type A2, USCG Type B1 or USCG type B2. Where you use it determines what type you use.

From the fuel inlet on the engine (usually the fuel pump) to the carburetor you must use Type A1 or A2.

Each fuel vent line or fill line must be USCG Type A1 or A2 and the line from the fuel tank to the engine inlet must be type A1 or A2; UNLESS:

if no more than five ounces of fuel is discharged in 2 1/2 minutes when:

(A) The hose is severed at the point where maximum drainage of fuel would occur,

(B) The boat is in its static floating position, and

(C) The fuel system is filled to the capacity market on the tank label.

Then you may use Type B1 or B2.

As a practical matter, few boatbuilders want to have to stock two types of hose, so most buy only Type A1 and use it everywhere. This is fine. Just be sure that you put in your owner's manual that the hose from the fuel pump to the carburetor and the vent and fill hose must be TYPE A1 or A2.

So whats the difference between A1, A2, B1, and B2? First the difference between A and B. A hose has to pass the 2 ½ minute fire test, B does not. The theory is the A is under more pressure than B, and being on the engine is exposed to more danger of fire than B. Since B is betwen the pump and the tank, if a leak occurs, the pressure rapidly drops to zero and the pump just sucks air, stopping the engine. Fuel doesn't get sprayed all over the place. With Type A, since it is between the fuel pump and the carburetor, it is under pressure and there is the potential that fuel will be sprayed around.

The difference between Type 1 and 2 is the permeability. All hose allows a small amount of vapor to pass out through the wall of the hose. The more permeable the hose is, the more vapor passes through. A1 and B1 pass much less than A2 and B2. About 1/3 as much. The Coast Guard Sets the standard for the amount that is allowed.

You do not have to use hose! You can use metallic lines. Some manufacturers do. For example, Mercury Marine inboard engines come with steel fuel line from the fuel pump to the carburetor.

Mettalic fuel Lines: If you use metallic fuel lines, the ones that run from the fuel tank to the fuel inlet on the engine must be one of the following; seamless annealed copper, nickel-copper, or copper-nickel. From the fuel pump to the carburetor they can be any metal you want to use. Beware. You could set up a galvanic couple and the tube will be eaten away like powder. Choose carefully if you use metal fuel line from the pump to the carburetor.

Anti-Siphon: The fuel line on a boat must run uphill, or else you have to have an anti-siphon device. An Anti-Siphon valve is that annoying little valve that most builders put at the tank outlet, that seems to get clogged at the most inconvenient times. So, if the top of the fuel tank is higher than the inlet on your fuel pump you have to put anti-siphon in the system. This is because the possibility exists that your entire fuel tank could siphon out into your carburetor, and fill up your manifold, and ruin your whole day! So, the solution is obvious. If you don't want this nasty little gadget in the fuel line, put the tank lower than the engine fuel inlet.

Clamps: If you use clamps, they must be used with hose designed for clamping. Sounds pretty obvious doesn't it. Be beyond the bead, flare, or over the serrations of the mating spud, pipe, or hose fitting; and, not depend solely on the spring tension of the clamp for compressive force. Again this is pretty obvious stuff. In addition, the law doesn't require it but ABYC standards and good practice require that clamps be at least ½ inch wide, and each hose should be double clamped.

Fuel Fittings: If you don't use clamps, but use fittings instead they must be:

A swaged sleeve;

A sleeve and threaded insert.

System Pressure Test: The entire fuel system must be pressure tested to insure there are no leaks. You have to test the system at least at three PSI, unless you have a long deep system. Then it must be 1 ½ times the greatest pressure in the lowest part of the system. For most boats three PSI will do.

Grounding (Bonding): All metallic components of the fuel system that are in contact with fuel must be electrically grounded to prevent a static discharge from causing a fire or explosion.

http://newboatbuilders.com/    Copyright 2006