Flexible Fuel Tank

[danielgoldberg]

Anyone have experience with these? I'm considering adding additional fuel capacity, and depending on how things play out we may consider a flexible tank. That said, the idea of having many gallons of diesel in a bag that might leak makes me a touch nervous. Am I being too conservative? Are these flexible tanks proven to be robust and reliable?

Thanks all.

[James S]

The folks that brought my boat over had three of them on board...seems like they were 10gal ea.
They had no leaks and after the 11 months it took to deliver the boat, they truly looked like they were brand new...no chafe from living in the bilge....nothing.

[ColdEH]

I think chafe would be the number one issue, make sure these things are tied down or in a container that fits them properly .

I have two decommissioned water tanks under my floors that would be a perfect candidate for a pair of flexible fuel tanks .

I would use them as a reserve only and pump the fuel out of them into the main tanks when needed. So they would be either full or empty. No chance for chafe . When they are full they would fit snug in the old tanks and when empted there would be nothing inside to slosh around .

Regards

[Terra Nova]

Flexible tanks are OK as a temporary expedient for an unusually long passage/delivery. But for permanent tankage, NO.

[Mike OReilly]

Originally Posted by Terra Nova

Flexible tanks are OK as a temporary expedient for an unusually long passage/delivery. But for permanent tankage, NO.

Can you tell me more about this Andy? I've got a decommissioned diesel tank and I'm trying to figure out what to do with it. I don't really need the fuel tankage (main tank is 80 gallons), but I've considered inserting a bladder just for the heck of it. My thought would also be to use it as storage and pump to the main tank when needed.

You've had a bad experience with these tanks?

BTW, I see this thread is pretty old. I hope the OP got the answer he wanted.

[chuckr]

we have a jeanneau ds40 that came with a 36gal tank -- not enough for long term cruising in our opinion -- we went to deltaville boat yard in the cheaspeake and with them did a lot of research of various methods of adding fuel capacity -- flexiable tanks, plastic tanks, aluminum tanks - a lot of research on cost, capacity, installation ect --
at the end of the day we chose a custom made aluminum tank that fit into a space jeanneau had left for a 3rd water tank -- worked out well and gave us a added 50 gallons - by making it custom made we were able to fill the void in perfectly and max out the space --
we then added a control panel that lets us choose which tank we are drawing from

[Terra Nova]

Mike--only the stories I've heard.

To fit a flexible tank inside an existing (leaking) metal tank, what do you do with the existing tank baffles? And these bladders have no baffles.



No. OK as a temporary expedient but I wouldn't have 1 on my boat.

[Mike OReilly]

Thanks for the suggestion chuckr. The old tank is sealed in the bilge area. It would be a devil to remove, and as I say, we're not hurting for diesel capacity. It's certainly not worth ripping the boat apart to get at.

I might just cut the top off the tank, and use the space as deep storage.

Originally Posted by Terra Nova

Mike--only the stories I've heard.

To fit a flexible tank inside an existing (leaking) metal tank, what do you do with the existing tank baffles? And these bladders have no baffles.

I assume I'd have to cut the baffles out. You'd think the flexible tanks would have some way of managing the slosh ... some sort of plastic baffle? As I say, it's not that we need the extra diesel, but I do have this empty space. It's not worth destroying my interior to rip out, so a bladder would work well IF it is safe to use.

[ColdEH]

Originally Posted by Mike OReilly

Thanks for the suggestion chuckr. The old tank is sealed in the bilge area. It would be a devil to remove, and as I say, we're not hurting for diesel capacity. It's certainly not worth ripping the boat apart to get at.

I might just cut the top off the tank, and use the space as deep storage.



I assume I'd have to cut the baffles out. You'd think the flexible tanks would have some way of managing the slosh ... some sort of plastic baffle? As I say, it's not that we need the extra diesel, but I do have this empty space. It's not worth destroying my interior to rip out, so a bladder would work well IF it is safe to use.

I have the same space, no baffles , it is being used now for storage , but the extra diesel would be fantastic. Keep them full or empty= no slosh. I would only have to fill up once a year while in the Caribbean.

Regards

[Mike OReilly]

Originally Posted by typhoon

I have the same space, no baffles , it is being used now for storage , but the extra diesel would be fantastic. Keep them full or empty= no slosh. I would only have to fill up once a year while in the Caribbean.

That's my thought as well. It would be nice to hear from someone who has actually done it though. I do wonder about dangers of chafe. A failure would be ... bad

[motion30]

the good quality flexible fuel tanks were used often in offshore powerboat racing. the good ones have foam blocks to control surge and sloshing.they seem to be trouble free in those conditions.. there is one brand made in New Jersey

[a64pilot]

Many thousands of aircraft are flying around with bladder tanks. Have been since before WWII. Never seen a chafe issue with them. Usually they last well beyond 20 yrs. You know when they begin to fail when you start getting lots of rubber granules in your fuel filter.

[model 10]

Originally Posted by a64pilot

Many thousands of aircraft are flying around with bladder tanks. Have been since before WWII. Never seen a chafe issue with them. Usually they last well beyond 20 yrs. You know when they begin to fail when you start getting lots of rubber granules in your fuel filter.

Oh, there are so many reasons you could not get boat owners to pay for aircraft quality fuel cells. They are dependable but they are very expensive and quite unique. Big heavy rubber bladders they are not.
I wonder if welded PVC like you might find in raft, dinghy, fender construction might be more appropriate than the usual aircraft type construction.

[Mike OReilly]

Originally Posted by Guy

Oh, there are so many reasons you could not get boat owners to pay for aircraft quality fuel cells. They are dependable but they are very expensive and quite unique. Big heavy rubber bladders they are not.

I wonder if welded PVC like you might find in raft, dinghy, fender construction might be more appropriate than the usual aircraft type construction.

Whoa... Tell us more. I might pay if the quality is worth it. Are you saying the bladder options available to boaters are different, and poorer quality, than those available to aircraft owners? Why would that be?


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[HopCar]

If you decide to go with a flexible fuel tank, take a look at Aero Tech Labs.
These guys make all kinds of very high quality flex tanks, including aviation, marine, military, and racing.
http://www.atlinc.com/

They will also build liners to fit into metal tanks.

We sold a bunch of their tanks back in the early eighties and they are a first class company to do business with.