Why not bladders?

[NorthernMac]

Hey guys,

Got a question, by mystic has a bladder for fresh water, and a bladder for black water, fiberglass tank of diesel.

The bladders seem quite tuff, think they are French make, forgot the name, if they have a issue I can just empty them and roll them up, remove and replace, they pretty much fit the shape of whatever surface.

Is there a draw back? Seems like these would be the default answer to tankage unless there is something I’m missing?

[Mike OReilly]

I had a water bladder in my previous boat. Worked great, but wasn't very large (100 litres perhaps). I've also researched diesel bladders as a possible solution to my aging iron tanks. Seems pretty viable.

One of the main challenges with bladders is chafe. They have to be securely mounted, but in a way that avoids all chafe. I think baffling is also an issue for big bladders.

[slug]

A water bladder works fine

Take care of them and they give a good service life

Stay away from fuel bladders

I can tell a pretty ferocious sea story about a fuel
Bladder rupturing at sea in a gale

It was a very bad trip

Don’t go there

[JPA Cate]

We had Vetus hypalon water bladders, they were original in our first Insatiable. They failed at about 20 yrs. along their aft seams (they fit under the settees). Their replacements, which were PVC and tedlar, failed at 3 weeks, and 2 weeks, along welds. Out of patience, as well as fresh water, we replaced them with s/s tanks, fabricated for us in NZ. It was one of the times we were glad we'd had the boss of the place measure the boat for them. We actually got them back to the boat before we realized he'd made two port tanks. He took the extra port one of them back, and made the starboard one, with only a little embarrassment, a good man.

One way to think about them, is "what happens if they leak?" I'm sure I'd not want to face a full black water breach, or even grey water.

Weighing that disagreeable job (the cleanup) against the convenience of the bladders, plus your boat's bladders have so far been reliable...and it's right down to a personal decision.

There are many plastic tanks made, and if you do a CF Custom Google Search on "plastic tanks + Peggy Hall", I'm sure you could find the ones she has posted links to. She says there is a wide variety to choose from, and her posts are reliable.

Ann

[chrisr]

we had a fw bladder in a previous boat...never any problems

some friends of ours have just had their s/s diesel tank fail (probably 20yo ?). major job to cut the tank into pieces from under the cockpit and remove.

rather than incur the very high cost of re-building the boat to fit a new s/s tank, they are replacing it was a bladder. putting in a sponge rubber liner first

seems like a good option

cheers,

[cortezsailor]

ATL marine fuel bladders are about the best . You can google not cheap but no issues with strength and durability . I agree most are cheaply made but I am
Impressed with this bladder

[JimsCAL]

My last 2 boats had bladder holding tanks. The one one the previous boat was troublesome, with the vent getting plugged and other issues. I replaced it with a rigid plastic tank. The bladder tank on my current boat has worked fine.

[mikedefieslife]

The Aussies seem more au fait with bladders.

The whole what happens if they leak is not more of an issue than all the leaking stainless or aluminium tanks we read about here. Various militaries around the world use bladders too. Just secure them and protect them against chafe. Pretty the mantra of everything on any moving vehicle. That however is easier said than done in some cases.

[a64pilot]

Bladders have several issues, they are sometimes used as fuel tanks in aircraft, but the preferred method is to seal the hundreds of rivet holes and use them as opposed to bladders.
Bladders can get wrinkles, these wrinkles are where you will find the water trapped that grows bugs and splashed over the wrinkles in rough weather to kill your engine, bladders also chafe and can wear though, and bladders have seams that can leak and come unglued or unwelded. Plus bladders deteriorate and need replacing.

SS rusts and often fails at the welds, aluminum corrodes, period, fiberglass can depending on the Resin not handle alcohol fuels etc.

The gold standard in my opinion is plastic, as long as it never gets exposed to UV, it has an almost infinite life. Whether fresh water, black water or fuel.

[slug]

Originally Posted by a64pilot

Bladders have several issues, they are sometimes used as fuel tanks in aircraft, but the preferred method is to seal the hundreds of rivet holes and use them as opposed to bladders.
Bladders can get wrinkles, these wrinkles are where you will find the water trapped that grows bugs and splashed over the wrinkles in rough weather to kill your engine, bladders also chafe and can wear though, and bladders have seams that can leak and come unglued or unwelded. Plus bladders deteriorate and need replacing.

SS rusts and often fails at the welds, aluminum corrodes, period, fiberglass can depending on the Resin not handle alcohol fuels etc.

The gold standard in my opinion is plastic, as long as it never gets exposed to UV, it has an almost infinite life. Whether fresh water, black water or fuel.

For custom shapes aluminum works well

For production plastic tanks look to oceanlink or mueller , hundreds of oddball shapes
https://www.oceanlinkinc.com/marine-tanks/

[mcarthur]

For an example, MV Dirona wrote about using on-deck bladders as long-range backup for their Atlantic crossing. Not something for everyday as it seems you're asking, but they can be stored below for when needed.

[Patrigo]

My vessel has had ss diesel and water tanks for 34yrs. I decided my diesel capacity
with 2 tanks, was more than adequate, so removed one, cut one side off, steam cleaned, re -welded, and refitted it as a water tank. An easy diy, job because they are ss. I would have lived with the too much diesel situation if they had been fabricated in anything else.

[dfelsent]

Two boats ago I had a problem with bilge water. Couldn’t find the leak. Water was not clear but not salty. Was a leaking black water bladder.
Boat had polyethylene water tanks and a monel gasoline tank.
My boat now has fiberglass water tanks and monel diesel tanks.
Polyethelylene for black water.
In your shoes if I could buy and fit a poly tank for black water I would.

[BlueH2Obound]

Originally Posted by dfelsent

Two boats ago I had a problem with bilge water. Couldn’t find the leak. Water was not clear but not salty. Was a leaking black water bladder.
Boat had polyethylene water tanks and a monel gasoline tank.
My boat now has fiberglass water tanks and monel diesel tanks.
Polyethelylene for black water.
In your shoes if I could buy and fit a poly tank for black water I would.

I really REALLY don't want to know how you figured out it was not salty . . .

[anotherT34C]

I like the idea of fuel bladders serving as an extra capacity on a long trip. I'd think better than the ubiquitous rows of 5gal fuel tanks tied to the liferail.