Diesel tank of ss? Aluminium? Fibreglass?

[Sand crab]

Originally Posted by GordMay

Stainless steel, if used for fuel tank construction, must be of the 316L, or 317L alloy, and a minimum of 0.0747 inch thick.

Just wondering why the minimum thickness? Is that a rule or regulation?

[hpeer]

Originally Posted by Lepke

If you make a new tank out of any metal, use a tank coating approved for diesel and the tank will last the life of the boat.

It just had a day tank made out of aluminum. I know about these sealants and have used them. But it escaped me to do this before filling the tank.

I think this is excellent advice. Perhaps even coat the outside if you are concerned about it getting wet.

The day tank is sitting high, well out of water, and on an open platform. I used nitrile anti-fatigue mats under the tank to provide for air flow and drainage.

[alaskanviking]

Originally Posted by BillKny

This is 100% irrelevant to the discussion at hand, since commercial diesel fuel in not mixed with ethanol.

Depends on the part of the country your in, several policy's on the books mandate adding ethanol or bio diesel blends. The navy has been doing experiments with blends for at least 14 years. Gas station diesel has increasingly been getting blends. AV fuel has blends on the books as well and all the manufacturers are experimenting/testing with their engines.

It used to av fuel and marine diesel was kept separate. However more attention has been getting put on these industries as they burn considerable amounts of fuel and don't have a lot of pollution controls comparatively.

It is correct these are not commonplace yet but it's pretty easy to see the trends and how laws are pushing things in the next 5 to 10 years. And we have some examples of how this works out in practice with the roll out of ethanol in gasoline.

I'm just saying that it is a valid concern and while it may take a little more research or a few dollars more to source a resin and or sealant that is compatible with these blends it's much easier to add that to the plan now than 5 years from now when your tanks are full. Much more of a pain to get coatings and resin to stick after it's been in contact with fuel.

I only want to do this once

[alaskanviking]

https://youtu.be/0cd4pmhD5jw

It's "two the horizon". They cut out the top of the old tanks and layer in 17oz cloth to make their tanks. I contacted them and they said they used a fuel specific resin sourced from RevChem Composites. I don't know much about that resin but am assuming it's a polyester or vinylester based resin since they said it smelled.

"A boat called Wanda" has also delved into this. UK based so different suppliers. But he found west systems epoxy is no longer recommended for diesel due to additives and blends. He ultimately found a special fuel and chemicals polyester resin that is compatible. 474 polyester resin.
https://youtu.be/Pr4T1DdyCbM

[JeremyFowler]

A big Thank You to all the interesting replies! The topic is, as with nearly everything it seems, a lot more complex than I had originally thought. I'm busy exploring options to relocate the position of the diesel tank to where it will be mainly out of the way of standing bilge water. Now I'll have a nice big spot for a spare anchor...

[friz]

Originally Posted by friz

Thanks for the info. I am about to have a 150 gal aluminum tank fabricated. If you please, what is the source of your specs?

I just had another idea. Could I make the whole space the fuel tank sits in a tank? A permanent tank. Part of the structure. Without getting into the specifics, loading, materials, features, is it feasible? The gasser in the photo is about to be removed and replaced with a diesel.

[alaskanviking]

Originally Posted by friz

I just had another idea. Could I make the whole space the fuel tank sits in a tank? A permanent tank. Part of the structure. Without getting into the specifics, loading, materials, features, is it feasible? The gasser in the photo is about to be removed and replaced with a diesel.

Maybe. That's called an integrated tank. Several advantages, strengthens/stiffens the hull, allows you to take advantage of the full space for a bigger tank. Negatives, if you get damaged or holed in that area your fuel drains out. On the other hand if that happens the fuel is the least of your concerns. You can also have insurance issues, they don't like abnormal setups in recreational boats. The strengthened or stiffened spot could break the boat in the worst of the worst if it's not done right, less likely but possible. You have to calculate the extra weight of more fuel and what it will do to your boat, ie too far aft and too much weight can make the stern too low, not good in rough water or could put your thruhulls underwater.

I'm leaning this way myself. Fairly certain it would give me an extra 20 gallons plus a small day tank on top. Will also allow me to angle the top which helps with condensation. Still mulling it over.

[hpeer]

Re: integral tank. If you are holed there the fuel/water runs out - true. But conversely the outside water does not run into the boat. It is a small piece of double hull, provided your lids are up to it.

Yet another compromise.

[Sand crab]

This company in the US makes custom fuel bladders. They can do any shape, here's two custom orders.

Marine Fuel Bladders and Auxiliary Fuel Tanks

[skenn_ie]

I would go with stainless, BUT ... ask a fabricator about radiused corners. Welds should be a little way from the corners as they will always be a weak point from the fatigue POV.

[Coltrek]

I have a shop have been specializing in SS for more decades than I would like to remember. I have made SS Tanks, repaired Aluminum tanks, but for myself, I removed a Perfectly good steel tank as preventative maintenance, replacing with a Poly Tank. 'Nuff said.

[mike mck]

Originally Posted by clakiep

If using fiberglass check the resistance to ethanol and maybe other chemicals. Occasionally a bymix of ethanol is not avoidable - and it is very agressive to most resins and some metals.

Capt. Claus - ocean tramp of the eighties

OP stated "Diesel Fuel Tanks" I have not heard of ethanol being used in Diesel. A very valid concern in gas boats.

Having said that I am a fan of Fiberglass tanks. Corrosion issues of metal tanks is a potential issue I don't want to deal with. As opinions are like Butts and everybody has one that is mine.
I am a 50 year old Diesel powered Hatteras with fiberglass tanks so my be a bit biased..

[Rotten Ricky]

First Quote: OP stated "Diesel Fuel Tanks" I have not heard of ethanol being used in Diesel. A very valid concern in gas boats.)

Second Quote: Having said that I am a fan of Fiberglass tanks. Corrosion issues of metal tanks is a potential issue I don't want to deal with. As opinions are like Butts and everybody has one that is mine.
I am a 50 year old Diesel powered Hatteras with fiberglass tanks so my be a bit biased..[/QUOTE]

As I have said in posts on this subject before, I cannot fathom why anyone would make a diesel tank of aluminum or stainless, particularly considering the corrosion of metals and the usual weakening of these metals when welded. Want proof of the suitability of fibre-glass? Consider that the underground fibre-glass tanks used in typical gas/petrol stations are guaranteed for 50 years!!! I think that points to their suitability! My understanding is that if gasoline/petrol is used, the inner layer must be made with vinylester resin or be coated with an epoxy inside, but that diesel does not affect polyester at all. And your fuel filter will be a back-up guarantee of pure clean fuel.

Compared to metal tanks, fibre-glass tanks do not corrode or sweat and therefore encourage algae growth in the bottom. They do not risk explosion (with gasoline use) and can be made with curved walls and in complex shapes to maximize tankage in the space available. They are usually easily repairable. The tank I had made for my previous boat increased tankage by 50% from what the flat sheets of metal would give me.

And get this - mine cost 60% of the cost of the much-smaller aluminum alternative. That was from a local Canadian professional maker of tanks that are often used for acids and other nasty stuff for industrial purposes. These guys are experts. When I asked about a warranty the guy laughed and wrote on the invoice "Warranted for 50 years"!

Knowing how easy it is, if I was needing a tank again I would build it myself for about 10% of the cost of aluminum! It is not rocket science - just common sense. The continued use of aluminum and stainless tanks indicates just how entrenched and possibly deceitful some boat manufacturers are to use such an inferior - even dangerous - product.

Incidentally, I recently spoke with the owner of my old boat. That tank is now about 32 years old in in perfect shape.

Cheers, and congratulations on "Team NZ" leading the world in battling The Bug and winning the Americas cup yet again.

RR.

[Winch_Wench]

We recently replaced one of our diesel tanks with an HDPE tank made to our specifications by Hercules Tanks in Katikati. Excellent tank and excellent service.

https://herculestanks.co.nz/

[daveNZ]

I had a diesel SS tank Replaced with custom from Plastic Construction, Avondale. Great quality and very good to deal with. You might get a better tank from Hercules in KatiKati.