Camera Buoyancy

[danhngo9594]

I just finished my Uw set up
Noted that I’m using 8” Acrylic Dome so I will need to add counter weight to hold the dome port down. Can you help me with these question?
- What would be the easiest way to find the correct neutral buoyancy for my setup? ( use luggage scale and check the whole setup in a bath tube?)
- How much weight normally you will add for holding the dome port? Heard about adhesive sheet lead for roofing.
- What floating arm brand is good? Something adjustable?
Thank you very much

 

[mi000ke]

Don'y know if this is the best way or even the correct way, but it made sense to me.....
I took my rig, waded into the ocean, attached a mesh bag to the rig and added weights until it started to sink.

 

[CanadaDan]

I used automotive wheel balancing weights (Amazon) on the bottom of the dome collar. Strong self adhesive and small so they allow for fine tuning. I also added a 1lb lead weight to the bottom of my tray to lower the centre of gravity. Combined with the float arms it trims the rig nicely. My housing is poly as well so it's very buoyant. The idea was to lower the centre of gravity by adding negative buoyancy to the bottom and positive to the arms. The rig now hovers perfectly level if I let go of it underwater. fwiw I use a combination of Seafrog's carbon fibre arms and StiX floats on the girder arms.

I did it in a pool so I could have the rig fully set up and extended so I could judge the trim. Amazingly the weights stuck even to the wet surface so I was able to submerge, judge and apply more as needed. If you're just doing the housing and dome a bathtub or large garbage can/storage bin full of water would do the trick.

 

[danhngo9594]

I used automotive wheel balancing weights (Amazon) on the bottom of the dome collar. Strong self adhesive and small so they allow for fine tuning. I also added a 1lb lead weight to the bottom of my tray to lower the centre of gravity. Combined with the float arms it trims the rig nicely. My housing is poly as well so it's very buoyant. The idea was to lower the centre of gravity by adding negative buoyancy to the bottom and positive to the arms. The rig now hovers perfectly level if I let go of it underwater. fwiw I use a combination of Seafrog's carbon fibre arms and StiX floats on the girder arms.

I did it in a pool so I could have the rig fully set up and extended so I could judge the trim. Amazingly the weights stuck even to the wet surface so I was able to submerge, judge and apply more as needed. If you're just doing the housing and dome a bathtub or large garbage can/storage bin full of water would do the trick.

Have you ever try the thing call Trim System of Ikelite?
I’m a bit worried to put weight on the dome and extension

 

[tursiops]

Have you ever try the thing call Trim System of Ikelite?

Not particularly adjustable.....scuba weights are usually 2 lb or more, with 1 lb being hard to find especially at a resort. That is LOT of weight to add to compensate for the dome!

 

[Pearlman]

How much does one need to over-compensate if testing in a swimming pool given the different densities of water?

P

 

[CanadaDan]

I've seen it but never bothered. The majority of the weight is the 1lb which I bolt to the tray. I only have a few oz's on the actual dome to adjust trim. I travel with the 1lb since as they are indeed impossible to find in most dive shops/operations.

Looking at the Trim System it wouldn't be hard to replicate with some aluminium stock and save $80+

 

[tursiops]

How much does one need to over-compensate if testing in a swimming pool given the different densities of water?

P

Hardly enough to worry about. 3% of the buoyancy you're adding. Make it a few ounces (100g?) heavy in fresh water, it will still be a slightly heavy in salt water. That is, if you add (say) 2 pounds (or 1 kg) buoyancy, 3% is just 1 ounce (30 g) change.

 

[Pearlman]

Ok, that reminds me because I have been mulling this on and off before - I can understand aiming for neutral buoyancy with a large heavy rig from 1" to m4/3 to DSLRs and above with their rather large UW housings. But what about a Gopro on a tray with two mini lights rig - should I even bother?

P

 

[tursiops]

Ok, that reminds me because I have been mulling this on and off before - I can understand aiming for neutral buoyancy with a large heavy rig from 1" to m4/3 to DSLRs and above with their rather large UW housings. But what about a Gopro on a tray with two mini lights rig - should I even bother?

P

Is it heavy and awkward to use? Do you tip forward if you hold the camera out in front of you?