Air tanks

[Carlsboats]

Looking for a source of supply for inflatable tanks to use for flotation in a 19' keel/C.B. day sailer which, like the Fish boatsd and H 12 1/2's, is not self bailing.. Ideally, would put
V-shaped tank(s) into forepeak and some additonal flotation into lazarette. Does anyone offer these, stock or custom?

[Carlsboats]

Looking for a source of supply for inflatable tanks to use for flotation in a 19' keel/C.B. day sailer which, like the Fish boatsd and H 12 1/2's, is not self bailing.. Ideally, would put
V-shaped tank(s) into forepeak and some additonal flotation into lazarette. Does anyone offer these, stock or custom?

[Carlsboats]

Looking for a source of supply for inflatable tanks to use for flotation in a 19' keel/C.B. day sailer which, like the Fish boatsd and H 12 1/2's, is not self bailing.. Ideally, would put
V-shaped tank(s) into forepeak and some additonal flotation into lazarette. Does anyone offer these, stock or custom?

[TomRobb]

Kayak/canoe dealers and catalogs have V shaped air bags. I've used truck tire innertubes in places where they don't show. You can get rapaired ones cheap from truck tire dealers. They're not pretty but they hold a lot of air and will form to fit a space. More or less.

[TomRobb]

Kayak/canoe dealers and catalogs have V shaped air bags. I've used truck tire innertubes in places where they don't show. You can get rapaired ones cheap from truck tire dealers. They're not pretty but they hold a lot of air and will form to fit a space. More or less.

[TomRobb]

Kayak/canoe dealers and catalogs have V shaped air bags. I've used truck tire innertubes in places where they don't show. You can get rapaired ones cheap from truck tire dealers. They're not pretty but they hold a lot of air and will form to fit a space. More or less.

[Evan Showell]

Here's a tip from the plastic dingy racing folks (sailing Jet 14s out of the Hunterdon Sailing Club on Spruce Run Res. in Northwestern N.J.) -- empty plastic soda bottles with top screwed on tight make good, cheap flotation. Obviously, they won't form fit a space, but they don't absorb water like some foams and they're cheap. Thought I'd pass that one along.

[Evan Showell]

Here's a tip from the plastic dingy racing folks (sailing Jet 14s out of the Hunterdon Sailing Club on Spruce Run Res. in Northwestern N.J.) -- empty plastic soda bottles with top screwed on tight make good, cheap flotation. Obviously, they won't form fit a space, but they don't absorb water like some foams and they're cheap. Thought I'd pass that one along.

[Evan Showell]

Here's a tip from the plastic dingy racing folks (sailing Jet 14s out of the Hunterdon Sailing Club on Spruce Run Res. in Northwestern N.J.) -- empty plastic soda bottles with top screwed on tight make good, cheap flotation. Obviously, they won't form fit a space, but they don't absorb water like some foams and they're cheap. Thought I'd pass that one along.

[Charlie J]

and if you run a bead of liquid nail or silicone around each of the jugs, they'll stick together and they won't rattle around either. Got that tip from a phone conversation with someone at the Gougeon's.

[Charlie J]

and if you run a bead of liquid nail or silicone around each of the jugs, they'll stick together and they won't rattle around either. Got that tip from a phone conversation with someone at the Gougeon's.

[Charlie J]

and if you run a bead of liquid nail or silicone around each of the jugs, they'll stick together and they won't rattle around either. Got that tip from a phone conversation with someone at the Gougeon's.

[Wayne Jeffers]

To veer slightly off-topic --

Since the foam-in-place foam is rather expensive, I've wondered whether some empty 2-liter bottles pre-filling the space, with foam poured over and around them, wouldn't effectively stretch the foam. Of course, you would have to come up with a way to prevent the bottles from floating until the foam hardened.

But with the recent mentions in this forum of foams absorbing water, and the prospect of moisture trapped in a substantially sealed compartment inducing rot, I've largely decided against using this type foam again myself.

I've long believed that water is much easier to keep in (where its not wanted) than it is to keep out. I mistakenly thought that the foam would effectively exclude moisture/water.

Wayne

[Wayne Jeffers]

To veer slightly off-topic --

Since the foam-in-place foam is rather expensive, I've wondered whether some empty 2-liter bottles pre-filling the space, with foam poured over and around them, wouldn't effectively stretch the foam. Of course, you would have to come up with a way to prevent the bottles from floating until the foam hardened.

But with the recent mentions in this forum of foams absorbing water, and the prospect of moisture trapped in a substantially sealed compartment inducing rot, I've largely decided against using this type foam again myself.

I've long believed that water is much easier to keep in (where its not wanted) than it is to keep out. I mistakenly thought that the foam would effectively exclude moisture/water.

Wayne

[Wayne Jeffers]

To veer slightly off-topic --

Since the foam-in-place foam is rather expensive, I've wondered whether some empty 2-liter bottles pre-filling the space, with foam poured over and around them, wouldn't effectively stretch the foam. Of course, you would have to come up with a way to prevent the bottles from floating until the foam hardened.

But with the recent mentions in this forum of foams absorbing water, and the prospect of moisture trapped in a substantially sealed compartment inducing rot, I've largely decided against using this type foam again myself.

I've long believed that water is much easier to keep in (where its not wanted) than it is to keep out. I mistakenly thought that the foam would effectively exclude moisture/water.

Wayne

[Todd Bradshaw]

Pour-in foam also gives-off a lot of heat as it expands. It might melt the bottles.

[Todd Bradshaw]

Pour-in foam also gives-off a lot of heat as it expands. It might melt the bottles.

[Todd Bradshaw]

Pour-in foam also gives-off a lot of heat as it expands. It might melt the bottles.

[Ed Harrow]

A couple of my friends are big into the airplane scene and make the obligatory flight out to Oshkosh (sp?)by-gosh. This year they met an individual who flew his ultralight up from South America.

He was concerned that should he drop into the Gulf his ultralight would sink nearly as a stone... What to do? Fill up all the empty spaces (wing structure, etc) with very thouroughly inflated condoms. Must have been interesting at customs.

I'd be very leary of using something like soda bottles, the pressure on them as they drop beneath the surface could collapse them much sooner than you might expect.

[Ed Harrow]

A couple of my friends are big into the airplane scene and make the obligatory flight out to Oshkosh (sp?)by-gosh. This year they met an individual who flew his ultralight up from South America.

He was concerned that should he drop into the Gulf his ultralight would sink nearly as a stone... What to do? Fill up all the empty spaces (wing structure, etc) with very thouroughly inflated condoms. Must have been interesting at customs.

I'd be very leary of using something like soda bottles, the pressure on them as they drop beneath the surface could collapse them much sooner than you might expect.

[Ed Harrow]

A couple of my friends are big into the airplane scene and make the obligatory flight out to Oshkosh (sp?)by-gosh. This year they met an individual who flew his ultralight up from South America.

He was concerned that should he drop into the Gulf his ultralight would sink nearly as a stone... What to do? Fill up all the empty spaces (wing structure, etc) with very thouroughly inflated condoms. Must have been interesting at customs.

I'd be very leary of using something like soda bottles, the pressure on them as they drop beneath the surface could collapse them much sooner than you might expect.

[Wayne Jeffers]

I dunno, Ed.

The soda bottles can withstand the internal pressure from the carbonated beverage.

I suspect that if the caps are on tight, by the time they reach a depth where the external pressure ruptures them, the boat would have much bigger problems anyway.

It's all hypothetical as far as I'm concerned, though.

Now that condom thing . . .

Wayne

[Wayne Jeffers]

I dunno, Ed.

The soda bottles can withstand the internal pressure from the carbonated beverage.

I suspect that if the caps are on tight, by the time they reach a depth where the external pressure ruptures them, the boat would have much bigger problems anyway.

It's all hypothetical as far as I'm concerned, though.

Now that condom thing . . .

Wayne

[Wayne Jeffers]

I dunno, Ed.

The soda bottles can withstand the internal pressure from the carbonated beverage.

I suspect that if the caps are on tight, by the time they reach a depth where the external pressure ruptures them, the boat would have much bigger problems anyway.

It's all hypothetical as far as I'm concerned, though.

Now that condom thing . . .

Wayne

[Henri]

A replacement bladder for a water system pressure tank might fit. The Sta-Rite of housefold size is 17 gal which would be what, about 135# floatation. Also, try one of your local packaging suppliers for foldable 5 gal water/liquid jugs, each will be 5 gallons or about 40# flotation. I think the camping retailers sell them abiet mucho$.

[Henri]

A replacement bladder for a water system pressure tank might fit. The Sta-Rite of housefold size is 17 gal which would be what, about 135# floatation. Also, try one of your local packaging suppliers for foldable 5 gal water/liquid jugs, each will be 5 gallons or about 40# flotation. I think the camping retailers sell them abiet mucho$.

[Henri]

A replacement bladder for a water system pressure tank might fit. The Sta-Rite of housefold size is 17 gal which would be what, about 135# floatation. Also, try one of your local packaging suppliers for foldable 5 gal water/liquid jugs, each will be 5 gallons or about 40# flotation. I think the camping retailers sell them abiet mucho$.

[MikeGardner]

Plastic soda bottles are designed only for internal pressure and will collapse easily, cap one and the submerse it and see.Also, the plastic used is thermo-formed...basically they are moulded as a stubby and then blown up while hot.Take one and hold it over a steaming pot..the thin midsection will shrivel and shrink.
I like the condom Idea but it would only be a shortterm plan due to the fragility of latex, they are designed as thin as possible..or so they say, and the stink of that stuff on them would be somewhat a turnoff ...for me anyway.The urethane foam sold at hardware stores is available in a low-expansion version. Whatever you try, I would plan on removal so if it deteriorates you can try another angle without major structural work.
I have seen fuel and water tanks, as well as dock floats, built by hot welding plastic. A dock manufacturer using this method could build you a set of tanks probably as thin as 1/8" thick. Then just strap them in or buld around them.
Good luck..keep us posted..mg

[This message has been edited by MikeGardner (edited 10-14-2000).]

[MikeGardner]

Plastic soda bottles are designed only for internal pressure and will collapse easily, cap one and the submerse it and see.Also, the plastic used is thermo-formed...basically they are moulded as a stubby and then blown up while hot.Take one and hold it over a steaming pot..the thin midsection will shrivel and shrink.
I like the condom Idea but it would only be a shortterm plan due to the fragility of latex, they are designed as thin as possible..or so they say, and the stink of that stuff on them would be somewhat a turnoff ...for me anyway.The urethane foam sold at hardware stores is available in a low-expansion version. Whatever you try, I would plan on removal so if it deteriorates you can try another angle without major structural work.
I have seen fuel and water tanks, as well as dock floats, built by hot welding plastic. A dock manufacturer using this method could build you a set of tanks probably as thin as 1/8" thick. Then just strap them in or buld around them.
Good luck..keep us posted..mg

[This message has been edited by MikeGardner (edited 10-14-2000).]

[MikeGardner]

Plastic soda bottles are designed only for internal pressure and will collapse easily, cap one and the submerse it and see.Also, the plastic used is thermo-formed...basically they are moulded as a stubby and then blown up while hot.Take one and hold it over a steaming pot..the thin midsection will shrivel and shrink.
I like the condom Idea but it would only be a shortterm plan due to the fragility of latex, they are designed as thin as possible..or so they say, and the stink of that stuff on them would be somewhat a turnoff ...for me anyway.The urethane foam sold at hardware stores is available in a low-expansion version. Whatever you try, I would plan on removal so if it deteriorates you can try another angle without major structural work.
I have seen fuel and water tanks, as well as dock floats, built by hot welding plastic. A dock manufacturer using this method could build you a set of tanks probably as thin as 1/8" thick. Then just strap them in or buld around them.
Good luck..keep us posted..mg

[This message has been edited by MikeGardner (edited 10-14-2000).]

[Oyvind Snibsoer]

Sorry, this discussion just got me started on some applied physics:

If a perfectly flexible container filled with an ideal gas is submerged 1/2 meter below the surface, the increase in pressure = .05 bar = 5%. The volume is then decreased by same amount. For a 1 liter perfectly flexible soda bottle, initially filled at surface pressure of 1 bar, the volume when submerged would then be (1 liter/1.05 bar absolute pressure)=0,95 liter. At 1 meter submerged the volume would be .9 liter and at 10 meters (2 bars absolute pressure) the volume would be 1/2 the original volume. The volume is again halved at 30 meters (4 bars abs.pressure) and again at 70 meters (8 bars abs.pressure) etc. The bottle still cannot break until the cap area is deformed, because the internal pressure is equal to the external pressure, minus some factor imposed by the mechanical rigidity of the bottle's walls. If a 19' boat is submerged much beyond 2 meters, then it's definitely sinking, and you didn't put in enough flotation, but those soda bottles won't pop until it hits the seabed at 500 meters+.

(If we assume that, in a 1 liter bottle where the whole bottle except the cap area is perfectly flexible, and the cap area has a volume of 2 cl=.02 liters, then the cap won't deform until the bottle's reduced volume < .02 liters. This will happen at a pressure greater than (1 liter/.02 liters) = 50 bar absolute = 490 meters.)


[This message has been edited by Øyvind Snibsøer (edited 10-15-2000).]

[Oyvind Snibsoer]

Sorry, this discussion just got me started on some applied physics:

If a perfectly flexible container filled with an ideal gas is submerged 1/2 meter below the surface, the increase in pressure = .05 bar = 5%. The volume is then decreased by same amount. For a 1 liter perfectly flexible soda bottle, initially filled at surface pressure of 1 bar, the volume when submerged would then be (1 liter/1.05 bar absolute pressure)=0,95 liter. At 1 meter submerged the volume would be .9 liter and at 10 meters (2 bars absolute pressure) the volume would be 1/2 the original volume. The volume is again halved at 30 meters (4 bars abs.pressure) and again at 70 meters (8 bars abs.pressure) etc. The bottle still cannot break until the cap area is deformed, because the internal pressure is equal to the external pressure, minus some factor imposed by the mechanical rigidity of the bottle's walls. If a 19' boat is submerged much beyond 2 meters, then it's definitely sinking, and you didn't put in enough flotation, but those soda bottles won't pop until it hits the seabed at 500 meters+.

(If we assume that, in a 1 liter bottle where the whole bottle except the cap area is perfectly flexible, and the cap area has a volume of 2 cl=.02 liters, then the cap won't deform until the bottle's reduced volume < .02 liters. This will happen at a pressure greater than (1 liter/.02 liters) = 50 bar absolute = 490 meters.)


[This message has been edited by Øyvind Snibsøer (edited 10-15-2000).]

[Oyvind Snibsoer]

Sorry, this discussion just got me started on some applied physics:

If a perfectly flexible container filled with an ideal gas is submerged 1/2 meter below the surface, the increase in pressure = .05 bar = 5%. The volume is then decreased by same amount. For a 1 liter perfectly flexible soda bottle, initially filled at surface pressure of 1 bar, the volume when submerged would then be (1 liter/1.05 bar absolute pressure)=0,95 liter. At 1 meter submerged the volume would be .9 liter and at 10 meters (2 bars absolute pressure) the volume would be 1/2 the original volume. The volume is again halved at 30 meters (4 bars abs.pressure) and again at 70 meters (8 bars abs.pressure) etc. The bottle still cannot break until the cap area is deformed, because the internal pressure is equal to the external pressure, minus some factor imposed by the mechanical rigidity of the bottle's walls. If a 19' boat is submerged much beyond 2 meters, then it's definitely sinking, and you didn't put in enough flotation, but those soda bottles won't pop until it hits the seabed at 500 meters+.

(If we assume that, in a 1 liter bottle where the whole bottle except the cap area is perfectly flexible, and the cap area has a volume of 2 cl=.02 liters, then the cap won't deform until the bottle's reduced volume < .02 liters. This will happen at a pressure greater than (1 liter/.02 liters) = 50 bar absolute = 490 meters.)


[This message has been edited by Øyvind Snibsøer (edited 10-15-2000).]

[rbgarr]

Slightly off-topic story follows:

One of my first jobs building boats was putting fiberglass duck hunting boat together. These were 13' long, narrow low-sided hulls with a high coaminged deck glued and pop-rivetted (!) together along an outboard flange. Of course the flange was covered with a lovely (sarcasm, here) vinyl 'rubrail'. The boats were painted in a flat camo green. I thought they looked like miniature C.S.S. Virginia's (or Merrimac's for the Yanks among us).

Anyhow, there were two compartments for foam flotation in these boats, one forward and one aft, and we used a two part product that would expand when mixed and poured in place. My first day I was getting 'training' from someone whose accent was not real clear to me and I misunderstood the proportions of the mix. I poured the foam mixture, lowered the deck on with the glue and clamped it down all along the edge (quality control took second place to speed here) and went off to another part of the factory off to work on fabricating more parts. Later I went back to check on the glue, so I could start drilling and pop-rivetting. The boat looked like one of those washing machine jokes where too much detergent has been put in and there's suds-foam flooding the basement! Except these bubbles were hard, sticky and hot to the touch with the bow of a boat sticking out and not much else in view.

Don't use that stuff in a wood boat...what a job it was to clean up!

[rbgarr]

Slightly off-topic story follows:

One of my first jobs building boats was putting fiberglass duck hunting boat together. These were 13' long, narrow low-sided hulls with a high coaminged deck glued and pop-rivetted (!) together along an outboard flange. Of course the flange was covered with a lovely (sarcasm, here) vinyl 'rubrail'. The boats were painted in a flat camo green. I thought they looked like miniature C.S.S. Virginia's (or Merrimac's for the Yanks among us).

Anyhow, there were two compartments for foam flotation in these boats, one forward and one aft, and we used a two part product that would expand when mixed and poured in place. My first day I was getting 'training' from someone whose accent was not real clear to me and I misunderstood the proportions of the mix. I poured the foam mixture, lowered the deck on with the glue and clamped it down all along the edge (quality control took second place to speed here) and went off to another part of the factory off to work on fabricating more parts. Later I went back to check on the glue, so I could start drilling and pop-rivetting. The boat looked like one of those washing machine jokes where too much detergent has been put in and there's suds-foam flooding the basement! Except these bubbles were hard, sticky and hot to the touch with the bow of a boat sticking out and not much else in view.

Don't use that stuff in a wood boat...what a job it was to clean up!

[rbgarr]

Slightly off-topic story follows:

One of my first jobs building boats was putting fiberglass duck hunting boat together. These were 13' long, narrow low-sided hulls with a high coaminged deck glued and pop-rivetted (!) together along an outboard flange. Of course the flange was covered with a lovely (sarcasm, here) vinyl 'rubrail'. The boats were painted in a flat camo green. I thought they looked like miniature C.S.S. Virginia's (or Merrimac's for the Yanks among us).

Anyhow, there were two compartments for foam flotation in these boats, one forward and one aft, and we used a two part product that would expand when mixed and poured in place. My first day I was getting 'training' from someone whose accent was not real clear to me and I misunderstood the proportions of the mix. I poured the foam mixture, lowered the deck on with the glue and clamped it down all along the edge (quality control took second place to speed here) and went off to another part of the factory off to work on fabricating more parts. Later I went back to check on the glue, so I could start drilling and pop-rivetting. The boat looked like one of those washing machine jokes where too much detergent has been put in and there's suds-foam flooding the basement! Except these bubbles were hard, sticky and hot to the touch with the bow of a boat sticking out and not much else in view.

Don't use that stuff in a wood boat...what a job it was to clean up!

[Henri]

This is a good subject.
For bladders, try the same entities that make fuel cells for race cars; these same people make inflatable water tanks for the military that are deliverable by helicopter to conflict sites. These bladders can be pnuematically inflated.
I ran into an entity named Sealed Air Corporation that specializes in protective packaging. They have a system and process for making low density foam (ie, 1#/ft3)structures in place, within trash bags and the like. Go to www.sealedair.com, then check out specifically thier INSTAPAK system.If this will work, and I think it will, find an entity in your neighborhood who uses it and beg for some. You've probably seen this stuff, its typically ysed for delicate electronics and the like. The neat part about this is that it has a vapor/water barrier, fits to your space, and does not stick to your structure, so you can shop it up and take it out quite easily.

[Henri]

This is a good subject.
For bladders, try the same entities that make fuel cells for race cars; these same people make inflatable water tanks for the military that are deliverable by helicopter to conflict sites. These bladders can be pnuematically inflated.
I ran into an entity named Sealed Air Corporation that specializes in protective packaging. They have a system and process for making low density foam (ie, 1#/ft3)structures in place, within trash bags and the like. Go to www.sealedair.com, then check out specifically thier INSTAPAK system.If this will work, and I think it will, find an entity in your neighborhood who uses it and beg for some. You've probably seen this stuff, its typically ysed for delicate electronics and the like. The neat part about this is that it has a vapor/water barrier, fits to your space, and does not stick to your structure, so you can shop it up and take it out quite easily.

[Henri]

This is a good subject.
For bladders, try the same entities that make fuel cells for race cars; these same people make inflatable water tanks for the military that are deliverable by helicopter to conflict sites. These bladders can be pnuematically inflated.
I ran into an entity named Sealed Air Corporation that specializes in protective packaging. They have a system and process for making low density foam (ie, 1#/ft3)structures in place, within trash bags and the like. Go to www.sealedair.com, then check out specifically thier INSTAPAK system.If this will work, and I think it will, find an entity in your neighborhood who uses it and beg for some. You've probably seen this stuff, its typically ysed for delicate electronics and the like. The neat part about this is that it has a vapor/water barrier, fits to your space, and does not stick to your structure, so you can shop it up and take it out quite easily.

[Dave R]

My co-worker and I were discussing this and he had a thought about using the 1L soda bottles. Cap them at sea level on a below 0F day. Then, when they warm up in the spring they'd be under a slight positive pressure inside. This would possibly buy you a few more cm before they collapse as well as a little more bouyancy.

[Dave R]

My co-worker and I were discussing this and he had a thought about using the 1L soda bottles. Cap them at sea level on a below 0F day. Then, when they warm up in the spring they'd be under a slight positive pressure inside. This would possibly buy you a few more cm before they collapse as well as a little more bouyancy.

[Dave R]

My co-worker and I were discussing this and he had a thought about using the 1L soda bottles. Cap them at sea level on a below 0F day. Then, when they warm up in the spring they'd be under a slight positive pressure inside. This would possibly buy you a few more cm before they collapse as well as a little more bouyancy.

[Wayne Jeffers]

An impressive analysis, Øyvind.

Empirically, capped empty plastic soda bottles will successfully withstand my weight when I try to flatten them before placing them in the trash. I project from this information that the water pressure necessary to cause them to fail would require a great depth. A depth at which I think, as you pointed out, the amount of floatation will have already proven inadequate.

Thank you for quantifying.

Wayne

[Wayne Jeffers]

An impressive analysis, Øyvind.

Empirically, capped empty plastic soda bottles will successfully withstand my weight when I try to flatten them before placing them in the trash. I project from this information that the water pressure necessary to cause them to fail would require a great depth. A depth at which I think, as you pointed out, the amount of floatation will have already proven inadequate.

Thank you for quantifying.

Wayne

[Wayne Jeffers]

An impressive analysis, Øyvind.

Empirically, capped empty plastic soda bottles will successfully withstand my weight when I try to flatten them before placing them in the trash. I project from this information that the water pressure necessary to cause them to fail would require a great depth. A depth at which I think, as you pointed out, the amount of floatation will have already proven inadequate.

Thank you for quantifying.

Wayne

[Todd Bradshaw]

I dug around in the garage and found a flotation gizmo that I salvaged from a damaged LaserII about ten years ago. It is a polyethylene cube, very much like the Reliance brand of water cubes that campers use. It holds 20 liters (about 11.5" x 11.5" x 10.5" tall) with no handles and a simple screw-on cap.
It says on it that it was built by Cousins-Currie Limited in Woodbridge, Ontario. As I recall, they were loose and three or four were distributed throughout the hull, kept in place by the internal bulkheads and/or hull shape. It's not really any heavier-duty than the good quality water cubes, so I don't know why they wouldn't work, though I might try to replace the spigot with a simple cap for security.

[Todd Bradshaw]

I dug around in the garage and found a flotation gizmo that I salvaged from a damaged LaserII about ten years ago. It is a polyethylene cube, very much like the Reliance brand of water cubes that campers use. It holds 20 liters (about 11.5" x 11.5" x 10.5" tall) with no handles and a simple screw-on cap.
It says on it that it was built by Cousins-Currie Limited in Woodbridge, Ontario. As I recall, they were loose and three or four were distributed throughout the hull, kept in place by the internal bulkheads and/or hull shape. It's not really any heavier-duty than the good quality water cubes, so I don't know why they wouldn't work, though I might try to replace the spigot with a simple cap for security.

[Todd Bradshaw]

I dug around in the garage and found a flotation gizmo that I salvaged from a damaged LaserII about ten years ago. It is a polyethylene cube, very much like the Reliance brand of water cubes that campers use. It holds 20 liters (about 11.5" x 11.5" x 10.5" tall) with no handles and a simple screw-on cap.
It says on it that it was built by Cousins-Currie Limited in Woodbridge, Ontario. As I recall, they were loose and three or four were distributed throughout the hull, kept in place by the internal bulkheads and/or hull shape. It's not really any heavier-duty than the good quality water cubes, so I don't know why they wouldn't work, though I might try to replace the spigot with a simple cap for security.

[TomRobb]

Yes, an interesting analysis. However, if your boat is below the surface, the system has already failed, and crush depth is irrelevent.

[TomRobb]

Yes, an interesting analysis. However, if your boat is below the surface, the system has already failed, and crush depth is irrelevent.