Camera bouyancy

[old_mike]

man, did i have a CF last night! Off of Catalina, my SPG started blowing more bubbles than i did, my drysuit leaked, my big 8 D light got in the way, and my camera rig snagged more kelp in 30 minutes that it did in the previous 4 years! On top of that, i left my fishing license on my dresser drawer so i couldn't even hunt bugs. WAAAAH! I will be taking an inexpensive toilet bowl float down on my next deep dive to research just that question!

All this in the research and dev't of making my camera CF-safe! I will be experimenting with attaching divelights (two of them); one to a strobe (for use as a modeling light) and one to an unused part of the tray. I figure that i will add about 8 "C" cells worth of negative buoyancy to the rig, but i will eliminate the need to have that bulky, heavy UK 1200 of mine hanging off my BC and banging into the rocks or strobe arm everytime i settle down for a shot. I think gear stress may be a major cause of accidents in some cases so i am making it a minor hobby to solve some of these problems as i encounter and forsee them.

DSAO! as soon as i do a deep dive, i'll post the fate of the poor unfortunate toilet bowl float!

 

[Greg G.]

Ok, you try the toilet float, and I'll experiment with the pvc and we can trade notes.

P.S. What's a "CF" dive, "DSAO"?

Originally posted by mike

DSAO! as soon as i do a deep dive, i'll post the fate of the poor unfortunate toilet bowl float!

 

[old_mike]

i cannot say what the acronym CF stands for (cluster umm. "fright?, no flailing? nope, ummm failing? welll, getting warmer) on such a civilized board, but if one is prone to CF'ing, i can certainly assure you that they are not doing the DS part of DSAO and will not live long enough to DSAO!

P.S. i can post the answer on the RSD board if you wish ; )

 

[herman]

how about cluster foul-up....??

 

[Iguana Don]

Greg,
Just some thoughts on all this, the size of your rig is approx. 1 cu ft, don't have my books with me, but some of you guys help out. In the Encyclopedia of Rec. Diving there is a chapeter on Bouancy & Recovery. You will have to displace approx 1 cu ft of water in order to make it neutral. Using the book you can determine what size PVC you will need.
On mounting, try those hose clamps that have the rubber lining, look under the hood of your car you can get them in stainless. Also the screw idea Herman thought of is good, try using a radiator drain plug instead, the one with the wings on it, then you can add to or take from without tools, most of these are made of brass. Go down about 3' feet and adjust.
The PVC is great, after all is worked out you can paint it to match your rig & it will look "hi tech"

Another thought, the 60 psi rating on schedule 40 PVC is internal bursting presure, I'm sure the imploding pressure is a lot greater, given the shape of the pipe, kinda like a submarine, their made for external pressure, not internal pressure.
Also you can find the toilet float bowls in styrofoam & shouldn't have any problems with crushing.

Don PHD-Southern Engineering

 

[old_mike]

oh good! we snagged an engineer to help contribute with our posts!! With my current rig, the one lousy item that tips buoyancy in the negative direction is the little Ikelite MS strobe and its 4 AA batteries. The mass of just this one item must be counteracted! Now, once that problem is solved, the mass of a 4-D cell wide angle strobe will be the next project and then a little Ikelite PC lite will have to be rendered neutrally buoyant. When i figure that out, well, then the CF'ing with camera gear in cold murky water in nasty surge and howling current at night off the Eureka oil-platform in 700 feet of water with shark chum all over the place will be negated (whew! got tired just thinking about all that)

 

[Greg G.]

I went shopping at Home Depot recently, but they didn't seem to make caps big enough for the 3 or 4 inch PVC, which I think is what I would need (don't ask me to try to calculate it). Plus it seemed to me that the bigger the PVC, the heavier the **** is, which I know doesn't come into factor as far as displacement/buoancy, but does figure in with the ease of handling.

A stryofoam float would crush big time, wouldn't it? I remember from my AOW the instructor took a styrofoam manican's head with him on the deep dive, it looked like a shrunken head at that depth.

If I use the clamps under my car's hood, wouldn't I lose my hood? <G> (Just kidding!)

Originally posted by don
Greg,
Just some thoughts on all this, the size of your rig is approx. 1 cu ft, don't have my books with me, but some of you guys help out. In the Encyclopedia of Rec. Diving there is a chapeter on Bouancy & Recovery. You will have to displace approx 1 cu ft of water in order to make it neutral. Using the book you can determine what size PVC you will need.

On mounting, try those hose clamps that have the rubber lining, look under the hood of your car you can get them in stainless. The PVC is great, after all is worked out you can paint it to match your rig & it will look "hi tech"

Also you can find the toilet float bowls in styrofoam & shouldn't have any problems with crushing.

Don PHD-Southern Engineering

 

[old_mike]

Ah, check the hardware store for black ABS drain pipe. That stuff is very light and it may even hold up in the pressure department as well. I have some leftover from one of my buildings i was rehabbing. I ought to test that and the toilet bowl float over the holiday! The stuff comes in the following diameters: 1 1/2, 2, 3, 4, 6 inches. The ABS pipe may not be in the same aisle as the schedule 40 white PVC with which we've been working.

 

[DIVERBRAD]

Yes camera comfort while diving is something that does take time to become proficient with. The PVC tubes ideas are interesting and seeing as how they didn't work you may be looking at other possibilites. Are you familiar with those water noodles (about 1-2 meters in length) you can buy them at Wall Mart. You see kids playing with them all the time during the summer. Two one foot sections on under either side of the camera, like pontoons. They are made out of a foam like material, like nerf stuff. I would suggest as well anything that is a dense foam, ie from kickboards used by swimmers, would not be as subject to the effects of pressures at depth, as would the soft water noodles suggested above. As well the soft pontoons on the underside of the camera prevent shock to the camera when resting it on the bottom for a shot. Just make sure that it won't tip over when placed on land. I have an Ikelite setup as well (video however) and negative buoyancy does suck a bit. But it doesn't seem to cause me undo discomfort, just holding a steady shot seems hard enough. One thing though if you ever have to ditch your camera it may be nice to attach a small lift bag to the underside, then you can just fill the bag and forget about it and hopefully it will be somewhere on the surface when the problem is taken care of. Hopefully this will never happen but it's nice to not have to worry about saving a camera rather than you and your buddy. Velcro straps should do the trick for attaching the buoyant pontoons. Good luck. Diverbrad

 

[Greg G.]

Not sure I follow what you're suggesting. The items you mentioned are made of foam, which WILL crush at depth.

Originally posted by DIVERBRAD
... Are you familiar with those water noodles (about 1-2 meters in length) you can buy them at Wall Mart. You see kids playing with them all the time during the summer. Two one foot sections on under either side of the camera, like pontoons. They are made out of a foam like material, like nerf stuff. I would suggest as well anything that is a dense foam, ie from kickboards used by swimmers, would not be as subject to the effects of pressures at depth, as would the soft water noodles suggested above...
Good luck. Diverbrad