Plastic fuel tanks vs Stainless steel?.

[mako101]

Anyone have any info regarding the pros and cons of plastic vs Steel?.
Aside from plastic is lighter.
Steel is stronger and probably lasts longer.

[finga]

Plastic degrades pretty quickly in the sun and eventually crack up.
Plastic isn't that much lighter really when it all boils down. They can use fairly thin stainless to make a tank but the plastic has to be fairly thick for a decent tank.
The weight difference would only be minimal considering all the other crap we put into boats.
The biggest differences are durability, toughness and price. But the stainless is only about 2x the price of a decent plastic tank and, hopefully, last 10X longer
http://www.biasboating.com.au/fueltanks.html

[Noelm]

funny thing about "stainless" tanks, if they are rsesting on damp/wet mounting they will rust out, a plastic one will never rust so 1 point, for plastic, a good plastic tank will take years and years to suffer UV damage, and they do not scratch your boat if you remove to refill (which you should) so I guess that is another plus for plastic, (by the way I have built in tanks, so not knocking metal just because I have plastic) I have had both at some time and reckon the plastic wins hands down, unless you want a big tank, not too sure how big they make plastic.

[peterbo3]

alloy.................................

[FNQCairns]

One of my observations on plastic is that it makes checking underfloor for secret leaks harder, because it seems to breath some petrol 'smell' through all the time.

Stainless has a habit of cracking where an alloy wouldn't, if O2 is excluded from SS it will eat itself.

I have an above floor SS tank I have used for years (like 15), heavily built and still as good as new.

Anyway if you go SS go heavy IMO

cheers fnq

[Noelm]

Alloy is not the be all to end all for fuel tanks, you will soon develop very small "pinholes" and the first one will only leak a really small amount, and just make a small mess, but after a while you will have a few holes, it won't happen over night, but it will happen!

[peterbo3]

Hi Noel,
My ten year old Lightning had an alloy tank. 3 or 4 mm. No leaks there. Never heard of pinholes in plate tanks. Bad welds, stress fractures from poor design or too thin sheet....yes. No pinholes though.

[PADDLES]

mine had pinholes pete. if it sits in water it'll corrode mate. mine was a reaction with a brass pickup fitting and salt water soaked carpet on the alloy tank, instant galvanic cell. tip is to keep em dry i reckon. apparently the s/s ones can split a little easier than the alloy because the alloy ones tend to be made of minimum 3 to 5mm plate and the s/s ones are a great deal thinner than that to keep the weight down.

[juju]

Thats one thing i worry about with my built in underfloor alloy tank....not being able to have a look at it and check it from time to time.....

[Noelm]

yep, I have seen heaps (well a few anyway) all with pinholes in them, seems like a very common thing especially if they can sit in a damp position.

[peterbo3]

Fair call. If the tank is poorly installed & dissimilar metals are in contact, then this can happen. I have seen it in tinnies where sinkers or hooks have been left in the bottom of the boat.
However, I maintain that if an alloy tank is correctly built & fitted, it should last for a very long time.

[PADDLES]

agreed, i replaced it with another alloy one. just remember that for a cell to be created you need water (electrolyte) so if you can keep it up out of any bilge water and keep it dry or at least let it get dry it'll last heaps longer. in my case the carpet was glued down the back of the tank and sitting in bilge water which wicked itself up the carpet, this carpet was also touching a brass fitting at the back of the tank and so any part of the alloy tank left immersed in the bilge water corroded damn quick because of the cell created.

[mako101]

I thought SS/alloy would get all the votes.
I think I will buy plastic.
The one I am looking at is a 50litre.
The Stainless one was a 40L and over double the cost.
It will definately be right out of the sun but also will surely have a bit of water sitting around it from time to time.
Also as mentioned, it will certainly be easier to lift a 50L plastic out of the boat rather than even a 40L SS, I think this is a good idea nothing worse than slopping a petrol trail through the boat every time you fill up.