Custom Plastic fuel tanks

[RDB]

Anyone know of a company who will build a custom plastic fuel tank? Its for a 40' boat.

[dereksireci]

Do not forget that the tooling for rotomolded plastics tanks is cost prohibitive for limited production. Another limiting factor is the physical size of the tank itself. The size of the oven also limits part size. These parts are made by pouring plastic in a bead form in a closed mold. The mold is then heated in an oven and rotated, (shake and bake). The rotation of the mold distributes the plastic to the desired area of the mold and therefore dictates part thickness. Unlike aluminum tanks which have baffles, rotomolded tanks do not. They do incorporate vertical structure to strengthen the tank but it does not prevent sloshing. There are several tank manufacturers. Inquire what shapes they have in your desired capacity range and make it fit if you can. Don't forget that a plastic tank grows after it reacts with the gasoline so the mounting method must not restrict this growth.
Still want a plastic tank? In my opinion, for a one off you would get better results with a fuel cell, (a bag). They just need a pattern, no molds. Again different installation requirements.

[T15740]

Last week, a Mercury repair shop told me that a large plastic tank w/baffels for ocean use is not necessarily a good idea because the wave/swell action creates vapor suction when under way causing the I/O or Outboard to have issues? Is this true, or just more creative nonsense. He recommended Aluminum tank for ocean use. If so, any idea what the specs are from the AYBC? I am an amature so I may be off on some of this but simply saying what I recall was told to me.

[RDB]

http://www.incaproducts.com

These guys make custom roto molded tanks, I have'nt heard back from them yet but the say on their site they've passed all the standards. Its a dodgy business making plastic fuel tanks which is why there are very few people doing it. If weight is of little concern aluminum is probably the best bet. We are just trying to shed lbs wherever possible, hence exploring the plastic.

[Robert Miller]

I speak from too little knowledge here, but....

I have read that plastic tanks for gasoline may represent some danger in that a static charge can build up on the interior surface as a result of the movement of the gasoline within the container. Since it is difficult to ground a plastic tank, a dangererous condition could result. So aluminum or stainless remains the better choice.
If weight saving is the goal, I am not certain how much benefit you achieve in the weight of the boat overall using plastic over aluminum.

Robert