Negative Box Compression

[junglelord]

No foam in the Robbe Seawolf....so thats not even close in my case.
What is glaring is how cold the water is, which directly deceases boyancy.
Now if you run in water that is just above zero celcius, be careful.
;)

[junglelord]

CRAFT! ... not 'art'. Art is for fag's!

David,

You know, considering, you have ignored me since the Seaview linkage question, your really full of yourself. Considering that I was peddeling you wares, you should grow up.
Dean

[Albion]

I was thinking in the lines of the bathyscaphe. (These submersibles use a float is filled with gasoline which is readily available, buoyant, and for all practical purposes, incompressible to maintain positive boyancy.) but instead of gasoline we could use something like vegetable oils.

That was because of extreme depth, if they were air filled they would collapse at depth gasoline filling prevents this. I dont think it would be an issue with a model

[Mankster]

After the Akula which was the first boat that needed any significant amount of foam for bouyancy, I have decided to try a different route with HMS Tireless - capped off thin wall acrylic tubing epoxied to the hull (mini empty WTC if you will). Still may need tiny amount of foam for final trim but I am hoping for a little excess boyancy and then trim with lead instead.

Bad move. Little flexibility as to placement of regid tubing, and the cylinders will be subject to much more compressive distortion than closed-cell foam. Think this move over again.

David,

[Subculture]

If you machine one end cap with a screw jack on the end (like a hand wound piston tank) you can adjust the buoyancy until it's spot on.

[Mankster]

If you machine one end cap with a screw jack on the end (like a hand wound piston tank) you can adjust the buoyancy until it's spot on.

Now theres an idea! May just have to give that a go.

[Subculture]

Silicone o-rings are nice and squishy (low shore number), and will conform well to the tube, plus they're highly resistant to any chemical attack, i.e. chlorine etc.

[Mankster]

Bad move. Little flexibility as to placement of regid tubing, and the cylinders will be subject to much more compressive distortion than closed-cell foam. Think this move over again.

David,

I hear you. I will need to get her wet and see how she behave before deciding what to do.

[He Who Shall Not Be Named]

Good, sound installation there. I assume the batteries are beneath the cylinder?

Put about two-pounds of lead weight at the keel, and the required amount of foam high, just under the designed waterline, and you'll be fine.

David,

[Mankster]

Yes, 12v NiHMH long pack with cells lined end to end goes under the WTC.

[Subculture]

Do you think you'll get problems with stability with this boat. After all I well remember the problems with the Akula, but there was no battery in the keel, the WTC was very low in the boat, and all that nice etched brass work high up in the boat to knock down the metacentric height.

Having said that, this is an early hull isn't it? With Dennis Caters uber-glass work that you could drive a truck over.

[He Who Shall Not Be Named]

Now that Andy raises that point: If I'm not looking at a flange .... Man! That's a thick ass hull!

David,

[Mankster]

Yes, 12v NiHMH long pack with cells lined end to end goes under the WTC.

Do you think you'll get problems with stability with this boat. After all I well remember the problems with the Akula, but there was no battery in the keel, the WTC was very low in the boat, and all that nice etched brass work high up in the boat to knock down the metacentric height.

Having said that, this is an early hull isn't it? With Dennis Caters uber-glass work that you could drive a truck over.

Yes its the earlier, built like a brickhouse, version. The Akula was a smaller scale (yet similar diameter WTC) and I wanted to get the high waterline those Russian double hull boats have. Hence the tendency to roll on the surface without the aid of a lot of foam and lead to lower the metacentric height.
Pauls got the same Trafalgar hull and after he got rid of the gell cell up front, raised the WTC and stuck the battery beneath it, it ran sweet as a button with next to no foam. So I have my fingers crossed. I do have a heavy sail though. Still time will tell :)

Ramesh