gas tanks

[missourihick]

I have an older runabout with a 26 gal steel tank under the bow. It says on the side coast gaurd approved. It is just thin mild steel or tin as most would call it,it has been in there since 1971,it is rusty around the bottom where it touches the carpet.I looked inside andthere is a little rust but not bad,.

 

[SPIKER]

I have seen them made form all kinds of stuff...

basic steel tanks have been around for ever and as long as they get coated with gas/fuel soon after they were made then the likely hood of rust is very small. when they do rust it is susally form one of 2 things.

1. water in fuel and the intake to engine does ont pick up the water off the very bottom of the tank.

2. the tank is left 1/2 full all the time and it condensates, again the pick up is too ihgh and the water is left in the tank to rust it out.

the new plastic ones will never rust. they also make boat tanks out of the plastic in 5 gallong size and some +/- too.

thickness of metal on the tanks is dependant on how big and who they are made. flat sides need thicker material than rounded sides. If you are building one for you're self then 16~18 ga is fine for up to 25 gallons, one side larger for 25 to 50 gallons (12~14ga) and anything over that then I would say at least a 11 ga materal.

Mark M /forums/images/graemlins/smile.gif

 

[daedong]

I talked to the Yamaha dealer yesterday about fuel tanks and he told me 90% of houseboats have mild steel tanks. He also recomended that in be around 400 lt or /forums/images/graemlins/confused.gif i think about 100 gallons.

 

[TOMDUALLY]

You may want to checkout tour local salvage (junk) yards and find a good and proven tank off a truck or something that could be adapted to fit. I'm thinking of saddle tanks square or round. LOL
TOM

 

[Buzz_Sawyer]

Well 55 gallon barrels are mild steel, and I see them used often on the farm for fuel tanks you could fashion a cradle and set it in ...then if it does rust after 30 years, spend $10 on a new one?

 

[daedong]

I have concluded that a mild steel tank will serve my purpose. I would like to thank everybody for there input but before i put this topic to bed i have one further question were, how, what with and why do i need to vent it /forums/images/graemlins/confused.gif

 

[Egon]

I do not know how but would say it has to be vented to the outside so there isn't an unexpected Bang from vapour fumes collecting in an enclosed area.

The filler pipe sould also be constructed so the tank - filler and fuel pump nozze are all grounded when filling.

Please note these are thoughts rather than true knowledge.

Egon

 

[Soundguy]

Could use a spin on breather element? ( looks like a spin on oil filter ). Lots of our heavy equipment has them on oil resv's.

Looking at the safety vent cap on my IH tractor.. it looks like simple baffled device as well.

Hey now thats an idea... he could just use a vented gas cap...

Soundguy

 

[SnowRidge]

Daedong, I owned an ocean going sailboat for many years. It was built in Taiwan with so called "black iron" fuel tanks. Turns out that black iron in this case meant mild steel.

The tanks were coated on the outside with red lead paint, but were uncoated on the inside. Because the boat wasn't built exactly according to the plans, the bilge was flat, and the bottom of the tanks frequently were slopped by bilge water. As a consequence, serious rusting took place on the outside of the tanks, but internal rusting was never a problem.

I sold the boat when she was about 25 years old, and the tanks had never leaked or been replaced. Others who owned sisterships weren't so lucky. Those unfortunates generally replaced the rusted out steel tanks with commercial plastic tanks.

Plastic tanks work well, but have two problems:

1. They often have no baffles. In a large tank, this is very bad.

2. They almost never have inspection/cleanout ports. This is more important with diesel than with gas (petrol down under?).

I would suggest going with commercial plastic tanks if you don't want or need baffles or cleanouts. If you do, build your own out of mild steel. Make the cleanout(s) big enough to stick your head in the tank.

Coat the tank's exterior with an epoxy coating of the type used on bridges following the maker's recommendations. I have used Amerlock, which may well not be available to you. It is a very thick paint-like product.

Be sure to ground the tank AND the filler. Put a loop in the vent line right before the vent. The tank's pick up tube should be a couple of inches above the tank bottom. If possible, screen the pickup.

I am most familiar with diesel powered boats. Their tanks almost always have drain plugs located low down on the side of the tank. I'm not sure if this is a good idea on a gasoline tank, though.

Use marine grade filler and vent hose, and double clamp all hoses at both ends.

Lastly, most governments have some rather strict regulations regarding fuel tank installations aboard vessels--especially gasoline powered vessels. There is a good reason for the regs. More than one gas powered boat has been blown sky high when a spark touched off gas vapors in the bilge. A gas tank installation done wrong can be deadly.

Please consult the applicable safety regs and keep you and yours safe.

Hope this of some use and good luck with your project.

SnowRidge

 

[em14]

If you don't vent the tank the outside air pressure will prevent the fuel from flowing well, if at all. I have seen automotive tanks where the tank's vent was stopped up completely collapse!
Leo