Buoyancy Issues..Please help...

[Titanite]

Hello,
I have a new Ikelite+Canon 7D set up with one single YS-110 Strobe. Im taking it into the pool next week to play around and add some buoyancy to it. I've read a bunch of posts about adding incompressible foam to strobe arms and base plate, also a PVC pipe zip tied to strobe arms. I was thinking of a PVC pipe zip tied to the base plate?? From your experiences, would this be ok in terms of balance, or should I have the flotation on the arms?

Anyone have this rig? If so what did you do to help the arm strain? How much positive lift did you have to add to make it comfortable?

Thank you in advance!
T

 

[bvanant]

PVC Pipe floats will compress like mad at depth. Get some divinycell or call the guys at Stix.
Bill

 

[Tienuts]

PVC Pipe floats will compress like mad at depth. Get some divinycell or call the guys at Stix.
Bill

While I do agree stix floats work well, I don't understand how PVC pipe floats will compress at depth.

 

[Titanite]

Does this look right for buoyancy calculation??

Upward Force=Volume fluid displacedxweight of sea water (64lbs/ft3)

Using the outer dimensions of my housing I get 316.8 cubic inches or .1833 cubic feet
I get UF=11.73LBS

 

[Titanite]

Tienuts,

Im confussed also. At 40m/140FT you have 71.6 psi water pressure.
2" PVC Schedule 40 pipe has a maximum working pressure of 280 Psi

 

[Latitude 59]

You didn't mention what port and arm you use. Recommend StiX floats for arm and pool time to dial in how you want. I have 7D/Ike/ULCS arms/Canon Macro 2.8 lens/DS-161 strobe so much larger/heavier but using Stix floats around port and arm have it dialed in perfectly so I can drop rig instantly or tuck under one arm (still attached) in case of emergency. Neutral UW, only notice size in current and on shore! Save spare floatation for when you add second strobe.

 

[furby076]

On a side note, I was told that a rig should be made SLIGHTLY negative. Neutral is very difficult to accomplish but slightly negative is more desirable. If a camera falls it will land on something and can be retrieved (barring you diving over a huge chasm). If the camera floats and goes to the surface...well good luck finding a camera floating in the ocean.

EDIT: In fact if you do lose a camera and it sinks you can typically get your fellow divers to go on a scavanger hunt

 

[WOODMAN]

Hokay, now for my 2 cents worth. As to the PVC pipe issue, I bet the confusion comes from someone assuming that the material in question was a pool noodle, not PVC pipe. I actually tried this, and yah, it's pretty much worthless. Compressed completely flat with no flotation. A piece of PVC pipe would work, I guess, and there are those who tried it and managed to make it work; but I have issues with that idea. (Okay, I'm picky..)
As to the idea of Stix floats on the arms, that originally interested me, but you have to pretty much permanently mount them on your arms, and being able to easily remove them for storage and transport was a prime consideration for me. And, seeing as how they are nothing more than hi-density foam in the first place, getting a piece of that Divinyl foam and making my own removable floats was a no brainer. It really wasn't that hard, as it cuts and shapes easily. (Having my own little shop with bandsaw and belt sander probably helped here, I must admit, but this could be done with hand tools if necessary.) The only tricky part was using a router table to carve out a channel down the center of the insides of the floats to fit over the metal strobe arm, But again I guess you could do this with a hand rasp or something. I must say though, ain't power tools wonderful?
Whatever you decide, good luck! Woody

 

[WOODMAN]

I just re-read Titanite's original post, and realized that the camera in question was an Ikelite SLR rig with the big lens housing. Well, in that case the band of floats on a belt which Stix makes for this purpose might be a good alternative for you. Fits around the lens and comes off without much hassle, and you don't have to spend time crafting up something. To each his own... Woody

 

[Titanite]

Hi Guys/Gals,

I found a great write up at another place that basically goes through step by step what I had done. There is also a handy buoyancy calculator for different density foams etc which also speeded the process up. Here it is incase anyone else is doing this and wants to save some time!

DIY Underwater Camera Floats & Strobe Arm Floats

For my rig (canon 7D with 1 strobe, and HD HERO on top) I was 2Lbs negative. Using the calculator I needed ~ 60 cubic inches of foam. I am going to make 2 blocks ~ 2x4x4 inches, which will be secured by sliding them onto a extended ball mount (attached pic). There is ~2.5 inches of "spindle" so to speak (3/4" diameter) that I will slide the foam block onto, and then into the handle to secure it. This should keep the camera upright (not having to mount any foam to the tray itself) and will be even side to side. The 1" ball will stop it from sliding off the top. Not sure of the balance in the water yet, but should be close.

Dont forget to account for the loss of foam from the 3/4 inch hole down the middle!!

I looked for divinycell foam everywhere in Canada. There are some boat shops that sell it, but its by the 4x8 foot sheet, and then you have to ship that, which is way over kill and very expensive.

Aircraft spruce does have a shop in Ontario if anyone is looking for some and they sell it 1" thick by 10"x12" as someone else mentioned in earlier posts.

Cheers
T