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[Greg Bridger]

Neoprene isn't buoyant at 100' (or hardly). It will compress and the tubes will mostly fill with water anyway. You need to plug the ends and make them airtight.

That seems like the best advise. You need a hard air cell. Any soft cell will just be compressed by the water pressure.

 

[3D diver]

Haven't read whole thread but it looks like a nice rig.

This foam doesn't compress much:

DIY Underwater Camera Floats & Strobe Arm Floats

DIVINYCELL FOAM PVC from Aircraft Spruce

I used it on my rig & the result is slightly bouyant on the surface and neutral at depth.

 

[300winmag]

Problem with rigid foam is I can't shove it all the way up the tube because of the bend for the lights. Tried a balloon yesterday and nada, not enough air in them to be bothered to do it. Guess I will leave it for now until I find something bendable and buoyant at depth. I'm going to look for something sprayable to fill the handles.

 

[caribean-ted]

Was gonna suggest you seal the tube, the air inside would keep it boyant, but the pressure could rupture the tubes so not sure that would be a good idea. LOL
Sorry I got nothing LOL

 

[fbk]

Problem with rigid foam is I can't shove it all the way up the tube because of the bend for the lights. Tried a balloon yesterday and nada, not enough air in them to be bothered to do it. Guess I will leave it for now until I find something bendable and buoyant at depth. I'm going to look for something sprayable to fill the handles.

Why spray anything in there? You do realize that anything you put in there makes it less bouyant than if it was just sealed full of air.

Seal them off. A plastic plug siliconed in place should do it. It shouldn't rupture unless you plan on diving the Titanic. That still may not be enough volume to add the required buoyancy so you might have to attach more, like a sealed PVC pipe.

 

[300winmag]

I could weld a cap on the bottom. I only go down to 100' but still unsure if thats a good idea as I dont know what will happen at that depth.
EDIT:
At 100" I would think nothing catastrophic would happen, maybe just a crack in the weld.... honestly I don't even see that happening. The aluminum tubes are almost 3/16 thick.

 

[3D diver]

Those tubes look substantial---how thick are they? (edit: d'oh question answered above! ) I'd guess sealing 'em up would be fine.

As for the rigid foam, you could break it up a bit for the part past the curve and shove in plugs for the rest.

If your tubes are substantial you may not get the lift you want, even with air in them, & might want to consider external floats. Maybe some foam cut to fit around the lights? My floats are big and clunky but make my rig neutral at depth.

 

[300winmag]

I would like to stay away from big and bulky so as soon as I find out for sure what will happen to them at 100' I will weld some caps on them.

 

[3D diver]

I hear you. My rig is laughably clunky, but very well ballanced at depth.

Good luck.

 

[nimoh]

I could weld a cap on the bottom. I only go down to 100' but still unsure if thats a good idea as I dont know what will happen at that depth.
EDIT:
At 100" I would think nothing catastrophic would happen, maybe just a crack in the weld.... honestly I don't even see that happening. The aluminum tubes are almost 3/16 thick.

instead of welding, you should thread the pipe and screw in a plug with an o-ring. That way if it does develop a leak, you can just remove the plug and drain it.