Bladders vs poly tanks

[AndyEss]

Originally Posted by UNCIVILIZED

What did you do to address the issue of keeping them in place should you suffer a knockdown? As well as protecting them from puncture & abrasion from items that get dropped into the bilge? Like the occassional screw, or tools. With the former item likely to wind up lodged somewhere underneath of them at times.

As far as I can tell, use of bladder tanks is original to the HC 38 Mk2 design and construction back in the late 70's/early 80's. There really isn't any other space on the boat I can find for the 300 gallon (two tanks) capacity of the bladders.
The cabin sole cross pieces appear very sturdy and might be expected to retain the bladders in place. The position of the bladders in the bilge is in an area that isn't often accessed, so dropping stuff on them wouldn't be an everyday occurence. As long as they have at least some water in them, they conform to the hull, and don't provide any space for items to get under them - as far as I can see, which isn't much. I haven't read anything on the Hans Christian forum about there being common issues with bladder punctures so after 35+ years of this design feature in this particular model of HC, I guess it hasn't been much of an issue.
I worked off of the polar ice pack north of Alaska as a much younger man, and we sling loaded fuel bladders under our helicopters and placed them for fuel caches at emergency landing areas all the time. Mind you, this was in temperatures 40 below zero - and never had those fuel bladders leak or burst. With a high quality bladder, you might have to work pretty hard to get them to fail.
Again, as in most things, you have to figure out the pluses and minuses of using particular components.

[SimonV]

Bladders are fine for increasing your capacity in the short turm. If you're after long turm go Polly.

[JPA Cate]

One problem, if you're just cutting the top off the tank, to then install the bladder, is that when getting full, they pooch up. The water pressure is likely to prise up any boards you've put there to retain the bladder in a knockdown. So you go to fill it, and the seat rises up, if the tank is under the settee, and with loud pops from the screws popping out!

Uncivilized, I'm not really qualified to comment. Both the epoxy and glass and the poly came with the boat. The epoxy and glass ones in this boat are under the cabin sole, and have three 8" cleanout ports per side, 400 l. per side. The poly one had no cleanout port. We've never had a problem with water going bad. The flavor has been good with all the materials we've used.

Ann

[Symphony]

Another way to look at this- the robustly built bladders are more costly per gallon than poly, but the cost is worthwhile if you need a movable tank or a complex shape.

Anything less in a bladder is asking to clean up a leak someday

If you have a rectilinear space for a permanent tank - quality plastic is cost effective

[coastalexplorer]

We have a 72 gallon water Bladder made by AVON USA. To Military specification.
no problems with it so far. Held in place with the webbing straps supplied, and anchored to attachment points built into the hull. location is under the Vee berth deck.

This replaced a 35 gallon NAUTA® Tank made in France that failed at the seams. Since Nauta are now located in Belgium it seems reasonable to assume that this bladder was over thirty years old? However NAUTA® corporation would NOT sell direct into CANADA so we could not do business with them.

[kryg]

I have 2 x100 liter for water and also 2 x 100 liter for diesel Plastimo Poly tanks in Skoiern IV for 30 years and no issues what so ever. I will use rubber bag tanks for cleaning the water-maker.

Originally Posted by cruiser77

We have just purchased a C&C 37R (totally excited), we will be making a lot of changes as she was used as a race boat and we are transforming her into a cruiser. As we go we will need some advice and help from all you folks!
First question, what is everyone's thoughts on bladders vs poly tanks, the good, the bad... all of it. TIA

[Martkimwat]

If you have the space to fit a rigid tank then that is preferable, the only advantage with a bladder tank is that they will conform to the shape of the space they are fitted, maximising the volume of water you can put in that space, as long as you line it first with piece of soft carpeting or similar as someone else suggested, to avoid abrasive wear.

[bongo]

Originally Posted by AndyEss

As far as I can tell, use of bladder tanks is original to the HC 38 Mk2 design and construction back in the late 70's/early 80's. There really isn't any other space on the boat I can find for the 300 gallon (two tanks) capacity of the bladders.
The cabin sole cross pieces appear very sturdy and might be expected to retain the bladders in place. The position of the bladders in the bilge is in an area that isn't often accessed, so dropping stuff on them wouldn't be an everyday occurence. As long as they have at least some water in them, they conform to the hull, and don't provide any space for items to get under them - as far as I can see, which isn't much. I haven't read anything on the Hans Christian forum about there being common issues with bladder punctures so after 35+ years of this design feature in this particular model of HC, I guess it hasn't been much of an issue.
I worked off of the polar ice pack north of Alaska as a much younger man, and we sling loaded fuel bladders under our helicopters and placed them for fuel caches at emergency landing areas all the time. Mind you, this was in temperatures 40 below zero - and never had those fuel bladders leak or burst. With a high quality bladder, you might have to work pretty hard to get them to fail.
Again, as in most things, you have to figure out the pluses and minuses of using particular components.

VOILA! Has a bladder inside the fuel tank that previously had seam leakage. This bladder has been in service at least 15 years. It is rigidly held in place and vented, (it does not collapse and expand as a fuel cell does). There has never been an issue with this bladder. In fact, it greatly reduces the amount of condensation in the fuel. In fact, no sign of water has ever been found in this tank. (I presume this is because the tank is not a cold metal surface that is in contact with the moist air.)
I have worked in power generation in Anatarctica, (where environmental laws are the strictest on the planet, and spills are not tolerated). As Andy said, above, the fuel was transported, in bladders, both by air, and on huge sleds which are dragged behind Caterpillar bulldozers in The Traverse from McMurdo Station to South Pole Station. And fuel is stored in bladders under the ice, in an arch tunnel system that is kind of like Quonset Huts under the surface. These are high quality mil-spec bladders that are better than most conventional materials at temperature extremes. (Coldest recorded temp now ~-136F!)
There is nothing wrong with a top notch bladder when properly installed and used.

[HopCar]

If you go with a bladder tank, this is the one you want. Aero Tech Labs makes very high quality tanks. They have been in the business more than forty years. I was a dealer for them back in the 70's and 80's. I sold a bunch of them, mostly large fuel bladders.
Aero Tec Laboratories - Aero Tec Labs - Aerotech - ATL - Aerotec - AeroTech Labs, Fuel Cells_Cell, Bladders_Bladder, Bladder Tanks_Tank, Potable Water Bladders, Pillow Tanks_Tank_Containment, Portable Tanks_Tank, Liquid Storage, Collapsible Tanks_Tan