Fuel Tanks

[casual]

Other than the obious such as runnong a screw thru the tank what are the down side of plastic fuel tanks.I have 3 water tanks in my current Boat a C&C 36 built in 78 still doing fine all plastic.I have replaced the Aluminum fuel tank corussion killed the bottom.I am completing a 48 ft sailboat and looking at all options,Any opinions will be appreciated Thanks

[DeepFrz]

The West web site has some thoughts and opinions and advice on wood/epoxy fuel tanks. Is that what you mean of do you mean the roto molded type plastic?

[Cheechako]

I dont see any down side to a good plastic fuel tank. I see down sides to most other types.... I've experienced 3 bad SS fuel tanks over my years of boating..... and it's a mess. I installed 2 plastic ones in my Catamaran. I think you can get custom ones made out of 3/8 thick poly... amazingly cheap too... not sure, I know they've made me balckwater and freshwater tanks....

[GordMay]

A study by Underwriters Laboratories (UL) for the U.S. Coast Guard has shown that aluminum tanks last an average of 10 years. Life spans are comparable for other metal tanks.

There is no data on the life of plastic (molded cross-linked polyethelyne, PE) tanks, but plastic has been used since the 1970s with no significant problems. They don’t corrode and they last almost forever. They have no seams or welds to leak.
You rarely see PE tanks over 100 gallons (380 litres) because they can’t be baffled.
PE tanks do permeate a very slight amount of vapour through the tank wall. If the amount is greater than that specified by the regulations, the space containing the tank must be mechanically ventilated. But, if it is installed properly there is no danger.
The problems that have occurred with PE tanks have been caused by people putting a hole in the tank, or by bad gaskets.

Fibreglass tanks have been used since the ’60s and work well with diesel,
although there are problems when used for gasoline. Some manufacturers of luxury yachts, such as Hatteras, use fibreglass diesel tanks and have not reported any significant problems.

[S/V Alchemy]

I switched out a 15 gallons Monel tank for a 10 gallon Tempo plastic gas tank for my Atomic 4, partly because I was rehabbing the entire fuel system, partly because I wanted more room in that locker, but mainly because I have trouble BURNING 10 gallons in a summer in a sailboat unless I hit 10 hours of calm and have to motor.

I have had no problems whatsoever with this new arrangement, but were you to go to larger tanks, it might be an idea to break up the fuel tankage via an intake manifold to fill two or three tanks (on my diesel motorsailer I have two 50 gallon keel tanks and a 40 gallon, post-fuel filter "day tank").

It is also a great idea to put a riser loop in your vent line and to increase it from 1/2 to 5/8" if possible. Since doing this I have had no more problems with condensate or insect activity clogging the vent hose.

[barnakiel]

depending on chosen type of plastic the issues may range from failure mode to repair-ability

but then they will not corrode (which is a huge downside to metal tanks)

b.

[pdxsailordiver]

I put twin 27 gal Tempo tanks in my 42' sailboat. The tanks do not have baffles in them. Below 1/2 tank with ocean swells the engine (4-107) will act like it is running out of fuel and I need to switch tanks. Tanks are under cockpit sole and on the center line. I was leery of the tanks because of the no baffles but was convinced they would be OK. Now I want to replace them with baffled tanks.

[casual]

Thanks for all the input.The baffell sititutation never occoured to me.I need to carry 200 plus gallons of fuel my thoughts were to split it into 4 50 gal,tanks.Now the baffell thing has me thinking my tanks will be mounted out board against the hull lots of roll.

[Cheechako]

Originally Posted by Cheechako

I dont see any down side to a good plastic fuel tank. I see down sides to most other types.... I've experienced 3 bad SS fuel tanks over my years of boating..... and it's a mess. I installed 2 plastic ones in my Catamaran. I think you can get custom ones made out of 3/8 thick poly... amazingly cheap too... not sure, I know they've made me balckwater and freshwater tanks....

I have purchased the custom welded Poly ones for indutrial uses (hot acid!) There is no reason they couldnt put a baffle in those.... they are welded construction and thick. Not sure what they would cost in smaller sizes, but were economical in huge tanks. One source: (no affiliation) Plastic Tanks, Custom Fabricated Tanks, Fabricated Plastic Tanks by Miller Plastics