New fuel tank for E35-II

I've finally embraced the idea that I need to replace my fuel tank. Maybe it was reading through Jeff's ordeal, or knowing the work and cost involved with replacing it, but reality has finally set in and I know that this tank is probably on borrowed time.



I'm considering going the way of Chaco, who replaced his with aluminum made by American Tank in Costa Mesa. However, Chaco hasn't been on the site for some time and so I'm not sure if the advantages of aluminum, or if the quality of the fabrication have held up since he replaced his tank. My (uninformed) instinct tells me that aluminum would corrode faster than steel, but other posts hold this option up highest. After discussing this with American Tank, a custom 40 gallon tank (design drawings courtesy of Chaco, who posted them to the site) would cost in the vicinity of $650, but that's an 18 gallon increase from the original, and I'd have to compensate for the additional weight of the fuel.

A plastic tank makes intuitive sense to me, but have also read that modern fuel blends will compromise the plastic, and that it doesn't have the rigidity needed for offshore work.

So much for instinct and intuition with material selection. So we're back to looking at steel, and after a phone call to Berry Sheet Metal in Costa Mesa, who supplied the Ericsons with their fuel tanks, it looks to be my best option at the moment.

Thoughts welcomed.

Aluminum

My original diesel fuel tank was aluminum and was not leaking when I replaced it with a larger capacity alum. tank.
I have never heard anyone recommend steel for a diesel tank.

Loren

ps: link to my tank replacement project.
http://www.ericsonyachts.org/infoexchange/showthread.php?6303-Diesel-Tank-replacement

Aluminum. +1
I welded up several aluminum fuel tanks on coastguard approved vessels when I was building professionally. It really is quite simple, and any "competent" fab shop should be able to do it for you, however someone with experience might be preferred. We would weld everything up and then pressure test the tanks for several days and also check for leaks with a spray bottle filled with soapy water. The coast guard inspector would then stamp the tanks with his seal and they were good to go. You of course won't need a coastguard stamp because you are not a papered coastguard approved vessel. I would recommend 3/16 plate thickness over using cheaper 1/8' and I would caution against using dissimilar metals for things like dip tubes and screw on fittings for hose barbs and such. also make sure not to drop a lose stainless steel nut or washer into the tank when putting on the inspection port in order to avoid any galvanic issues down the road. And finally be very stingy in you're use of pipe dope or plumbers tape because they both to funny things when diluted into your Diesel fuel.

...and you'll have all the inspection ports you want with a new tank.

I have been told that sufficient thickness of aluminum is important, and that some early boats had walls too thin.

$650 sounds very reasonable, considering the importance of a clean tank offshore.

ignacio said:

I've finally embraced the idea that I need to replace my fuel tank. Maybe it was reading through Jeff's ordeal, or knowing the work and cost involved with replacing it, but reality has finally set in and I know that this tank is probably on borrowed time.

I'm considering going the way of Chaco, who replaced his with aluminum made by American Tank in Costa Mesa. However, Chaco hasn't been on the site for some time and so I'm not sure if the advantages of aluminum, or if the quality of the fabrication have held up since he replaced his tank. My (uninformed) instinct tells me that aluminum would corrode faster than steel, but other posts hold this option up highest. After discussing this with American Tank, a custom 40 gallon tank (design drawings courtesy of Chaco, who posted them to the site) would cost in the vicinity of $650, but that's an 18 gallon increase from the original, and I'd have to compensate for the additional weight of the fuel.

A plastic tank makes intuitive sense to me, but have also read that modern fuel blends will compromise the plastic, and that it doesn't have the rigidity needed for offshore work.

So much for instinct and intuition with material selection. So we're back to looking at steel, and after a phone call to Berry Sheet Metal in Costa Mesa, who supplied the Ericsons with their fuel tanks, it looks to be my best option at the moment.

Thoughts welcomed.

Click to expand...

I replaced my original galvanized tank on my '73 E-32 MkII back in about '78. No regrets and it is still doing just fine! It's 1/8th inch thick and was painted with zinc chromate primer followed by a good epoxy paint.

Later when I changed out the Atomic 4 for a diesel, I easily converted the tank by adding a return fuel line.
My boat was originally in Florida salt waters from '73 till '90 and now resides in the Great Lakes region.

BTW - My clue for need of replacement of the galvanized tank was smelling gas and seeing a bilge full of gasoline! ....Watch-out - the underneath center bottom was the first area to give way due to salt water trickling down the rudder post and under the tank!

Hope this helps with your decision.

I have a plastic tank in one boat. The results have been good so far. The advantage is you can see the fuel level in it. I expect that this tank will last 30 years. I have the aluminum tank in the 34 and it still looks like new. I did a through a check as possible last year. The diesel does not seem to effect the aluminum much. Do not use a steel tank on diesel!!! the results are disastrous unless you consider 30 gallons of diesel in the bilge normal. Galvanizing does not help much. The water and some nasty acids are responsible.

One advantage of a metal tank, any metal is you can have baffles inside so several hounded pounds of fuel doesn't slosh around so much. Hard to do with plastic.

I see that the aluminum option is popular. I haven't heard many reasons why, however. I did have a look at this article, which shed some light. Plastic is out of the question for me...I'll need the rigidity and strength of a metal tank.

Diesel Tank Fuel Design
http://www.passagemaker.com/articles/technical/fuel-systems-technical/diesel-fuel-tank-design/

I hear the warnings against using steel, however (monel? galvanized? stainless?). Is this about how diesel interacts with steel that's the problem (promotes corrosion or fuel contamination?), or simply that aluminum's properties make it a more "modern" technology, even if being more susceptible to "exotic corrosion" as stated in the article?

Aluminum is a top choice I think largely because it is easy to work with, which cannot be overstated and really has to be experienced to be appreciated I think. Working with aluminum is like a day in heaven compared to many other materials. It can be cut with a jig saw, table saw, skill saw, welds cool in seconds ect.
Also it is light and strong and resistant to corrosion if done right, and lastly its easy to make custom fitted shapes and sizes quickly. fiberglass is too time consuming for most to even consider. Roto-molded plastic would be costly for a custom shape and also is not as strong as metal, and brings its own set of issues for attachments and fittings. stainless has problems in oxygen starved environments and is more prone to noisy oil-canning than aluminum per given weight of plate. I'm sure I am missing some other materials and benefits/detractors too.
aluminum would not however be my top choice in a constantly half filled bilge/keel type area, fiberglass would probably be the best material then but what a chore!

Stainless?

My tank is a 1990, 18 gauge, 316 stainless replacement (in a 1981 boat) from Vic Berry Sheet Metal. It is probably the original size and shape. I don't know why it was replaced so early or why in stainless. Since Berry built it and the original, I would ask them for a cost estimate in stainless and a list of advantages/disadvantages so you could weigh the options. If my tank were really difficult to get in/out I would seriously consider extra cost for extra longevity.

I love my stainless tank. I had it empty this summer to clean out gunk and add access ports to each bay. It looked great inside and out. I had just a little rust staining on the bottom of the tank where it sits on the TAFG supports. Inside looked great no rust.

Mark

That's a fine looking tank with very likely a long life still ahead of it. Did you cut the hole with a plan to add an inspection port?

What hole?

Yes. I added four access ports to the top of the tank, one in each bay. The E36RH has REALLY nice access to all the tanks under the settees. I am going to add 3 access ports to my stainless water tank this year.

Short story long:
I had thought about access ports when I got the boat four years ago but I could not justify the cost at that time. Then sometime last Fall-Winter I sheared the fuel tank vent fitting off the outside of the boat. I noticed the missing vent a year ago December and fitted a new one but didn't think about how long the tank had been exposed to water entry. This summer I had engine issues and diagnosed water in the tank so I had it pumped and dumped. My fuel vent fitting was installed directly under the forward-most deck scupper so all the deck water from the front half of the boat drains overboard over the vent fitting or the open pipe if it is missing! I couldn't easily move the vent so I switched to an Atwood trap vent fitting for added insurance. Below is the Seadog standard vent in it's poor location.


I knew I wanted to have access to each bay so I could clean the tank. I had looked at a lot of other peoples access ports and some of the commercial versions but over the past four years of thinking about it I figured out how to add them for much less cost. My tank level sensor screws are tapped into the tank top so I decided to use tapped screws for my access plates. This avoids additional inside backing plates and the expense of bigger nuts and bolts. I needed only 4 plates and 16 #10 ss screws per plate. I decided on 6 inch square access holes coved by 8 inch square 304 ss 10 gauge plates pre-cut from McMaster Carr to avoid cutting. I used 3/32" thick, Buna-N rubber sheet cut to 8 inch square for gaskets. Cutting the 18 gauge tanks was not bad with a jig saw and several blades. Drilling and tapping the tank was easy. The hardest part was drilling the screw holes through the thicker cover plates with my little drill press. It took several cobalt bits as they dull fast in stainless. Total cost for 7 plates, sheet rubber and screws for fuel and water tanks was under $100. The plates are as stiff as the tank and seal well. I probably could have used fewer screws and probably will for my water tank. It is really nice to be able to access the entire fuel tank if needed although cleaning out the creepy crawlies I can see in the water tank is probably a higher priority.

Mark



Mark

Nicely done! I switched to a trap style fuel vent as well, that combined with installing a new fuel fill base and cap ended my watery fuel issues too. These little fixes really add up to a exponential degree of usability and reliability in the end.

I went the aluminum route and had the new tank made to the same size as the old. It will fit through the lazarette. It is a tight fit, but with some jiggling it works. Don't know if all the tanks were similar but the old one the pick up tube was tack welded to the front of the tank all the way down to the very V at the front bottom. So every sediment piled up around the pickup. The new one is close to the bottom but not touching.