Buoyancy modifications?

I have been reading about buoyancy modifications being made to camera rigs to offset underwater weight due to arms, strobes etc. It seems most of the solutions revolve around making the strobe arms mode buoyant. What seems to be lacking is the input and opinions from the video folks.

I would like to add some buoyancy to my rig. I have accumulated some additional weight in the form of lights, batteries and arms. During night dives I mount an additional spotting light so I don't have to run the lights full time. Recently I added an additional arm to use for a slate, etc. This has all added up to a somewhat heavy rig underwater. I could add some buoyancy in the arms as many do, but I don't like that idea for video. Many times I have my arms folded up during the dive, not using the lights; it seems this would limit most of the techniques used to float the arms.

Right now I am leaning towards cutting some 1 inch think closed cell material the shape of the top of my housing, shaping and affixing it leaving room for the ULCS ball adapters.

I was curious to know what everyone was using, if anything.

Ryan

I use closed cell foam just like you are talking about.

My lights, arms and housing are all slightly negative. Individually not bad, but added up, made my system more negative than I'd like. Not knowing how much buoyancy I would need, I made closed cell foam sticks 1"x6".

The cc foam works well, but it is very gritty and you need to apply several coats of resin.

I know some people use tubes made of PVC or aluminum.

The most original and cheapest solution I have seen comes from Chris Wilk, a very talented videographer who's has some of the best macro video I have ever watched. He uses empty water bottles.

Yeah, I really enjoyed the re-engineered soda bottles as well. Easy to replace

It seems that those bottles (and many other solutions) could become rudders once in water. Where did you attach the foam sticks?

I use closed cell foam just like you are talking about.

 

My lights, arms and housing are all slightly negative. Individually not bad, but added up, made my system more negative than I'd like. Not knowing how much buoyancy I would need, I made closed cell foam sticks 1"x6".

 

The cc foam works well, but it is very gritty and you need to apply several coats of resin.

 

I know some people use tubes made of PVC or aluminum.

 

The most original and cheapest solution I have seen comes from Chris Wilk, a very talented videographer who's has some of the best macro video I have ever watched. He uses empty water bottles.

 

Right on top of the housing. Attached with rubber bands. High tech rubber bands.

I will use black surgical tubing with my new housing. It is stronger, I can custom cut the length and being black it will blend in with the housing.

I found on top was the best place as putting it anywhere else made the housing float towards the added buoyancy.

I will probably make longer sticks for my new housing as it is 14" in length.

James Wiseman wrote a great "how-to" on adding buoyancy with closed cell foam.

DIY buoyancy

That is quite a contraption there! I use high density foam and mount on the bottom with a tripod adapter. Very sturdy and very reliable.

See link: http://www.bluespheremedia.com/production/...80ED12486C.html

Reef Photo occasionally stocks Core Cell A500:

http://www.marineware.com/ccp_2.asp

Core Cell A500 weighs @ 5 pounds per cubic foot (variances exist in the manufacturing process......see spec sheet links below) and therefore will offer @ 59 pounds of lift per cubic foot in salt water.

According to the specs:

http://www.noahsmarine.com/United_States/C...emicals-us.html

For specs in meters, follow this link:

http://www.marineware.com/pdf/ccp/MW_CCP_2_1_AGrade.pdf

Core Cell A500 has a compression strength rating of 115 psi (at least 200' deep?)

Core Cell generally comes in 4' by 8' sheets, common thicknesses of 1/2" or 3/4" thick. It can be cut easily with a matt knife. Core Cell A500 can also be sanded to shape. If you contact Reef Photo ( a forum sponsor ), they may be able to supply you with your exact needs of Core Cell A500 for your own DIY project, thereby avoiding the need to invest in a whole sheet.

I have used Core Cell (around my strobe arms) and have been pleased with the results.

Core Cell, in its many variables, has been used to construct everything from sailing yachts to submersible robotic submarines.................

My Gates needed extra buoyancy to offset the light batteries and I made two buoyancy tubes similar to the ones Gates sell today.

My floats are made with 10-bar-rated ABS pipe purchased in the UK. A friend got it for me from a builder's merchants. The ends came from RS, purchased online. I don't know if they carry the pipe itself. The pipe was cut to length and the ends glued on with ABS solvent cement. In other countries the ABS may not be available but I have friends in the USA who have had success with similarly strong white plastic tubing that I think was UPVC. My floats are heavy because I made them for doing some very deep trimix diving. For shallower diving you might be able to get away with lower grade lighter tubing. In that case the ends might have to be screw-on ends with O-ring seals. However the mountings for these ends usually still needs glueing with solvent adhesive. I made a float some years ago using this lighter grade pipe and ends and I think the parts came from Plumb Centre. The pipe diameter is 2"/50mm or you might use the next larger diameter depending on how much buoyancy is required.

The floats are quite useful. They give the housing a bit of protection and I also use them as handles in some situations. They are attached to the housing with stainless steel jubilee clips (hose clips) threaded through slots machined in the housing's frame (which I'm sure Gates would not recommend!). Again these came from RS.

I recommend flotation is put at the top of the housing so that the centre of gravity makes the housing tend to stay upright by itself.

p.s. Check out "Divinycell" too if you're researching closed-cell foam

p.p.s Some Kris Wilk videos

I use high density foam and mount on the bottom with a tripod adapter. Very sturdy and very reliable.

shawnh, that looks pretty good. How does the tripod adapter mount to the housing? In my research I ran across some posts where you were talking about the tripod adapter, but I could not tell from the pics how it mounted? I am assuming the battery pod grooves?

Thanks to Bob and Nick, I have some more reading to do