Neutral Bouyancy on DSLR rigs

[gradient 1]

Hello fam,

Thought I'd share my rig with you and get some advise on how to make this beast neutrally bouyant. I have ran out of options on how to get it as close to neutral as possible. I only used Stix floats and these were the results:

Note they were weighed in freshwater (bathtub setup).

 

Rig for Macro:

-Subal ND700 , D700 with Nikkor 105VR 2.8

-Subal FP-FC105VR macro port with custom Stix float

-2x YS-D2 with neoprene jackets

-2x 8 inch ULCS arms with 3x jumbo stix floats on each arm

-2x 5 inch ULCS arms with 1x jumbo stix floats on each arm

-2x sync cables

-7x clamps

-L&M Sola 800 for focus

-Macromate (By Backscatter) for supermacro

Weight underwater: -1.06 lbs

 

I'd like to get this to at least close to neutral however with 1.06 lbs to go, I don't have space to put on floats anymore. Or do I just do DIY rought and zip tie floats onto the arms?

Without the Macromate I got it down to -0.67 lbs tho. Would this be already neutral in saltwater?

Any suggestions would be appteciated. Thanks!

 

Daniel

Edited April 8, 2021 by gradient

[TimG 62]

Hey Dan

I ran into the same issue. My solution was a 10" arm across the top of the housing then using 2x triple clamps to hold that. See photo. You then attach the usual arms in the spare clamp space. The extra 4x jumbo Stix provides 726gms of extra buoyancy.

I've found this works really well and its very good for handing the system up or down. It's not as bulky as it may appear and, as you can see, it provides the perfect place for the dive computer.

One thing I would suggest if you go this route, get triple clamps with the cutouts.

[gradient 1]

Thanks Tim. I find this interesting in that a the dive computer is already in front of me vs having to strap it onto the arm. I do want to know how you would go about mounting the focus lights? Or are you completely omitting it in this setup?

[TimG 62]

26 minutes ago, gradient said:

Thanks Tim. I find this interesting in that a the dive computer is already in front of me vs having to strap it onto the arm. I do want to know how you would go about mounting the focus lights? Or are you completely omitting it in this setup?

Yeah, I really like that dive computer set up.

Like you I use the Nikkor 105mm a lot. I usually use it with a snoot on the Retra Prime. The pilot light on that is good enough not to need a focus light.  

However, when I was messing about trying to work out the best Stix arrangement on the cross arm, I did find that if you use 2x whole Jumbo Stix plus 2x 1/2 Jumbo Stixs (ie, cut one in half), you could position all the Stix in such a way that there was space to screw a ball mount on to the 10" arm (it has a handy screw hole fitting on it!). So the arrangement was 1.5x Stix - Space (for Focus light mount) - 1.5x Stix. You reduce the buoyancy by 1x Stix ( so -181gms) but have space for a focus light if you need it.

Just to give you an idea, with the Nikon D500/Nikkor 105mm and the Subal FP-FC105VR port plus 2x Retra Prime strobes and one Retra LSD snoot, I found I needed a total of 12x Jumbo Stix and this made my system slightly positively buoyant. 

[ChrisRoss 150]

That may well work, but just looks so bulky to me! 

If you take off the 5"arms/floats you'll drop 180 gr x 2 = 360 gr buoyancy then replace them with INON mega floats - small size which are 390 gr buoyancy each that will add 420 gr of buoyancy to the rig.  You'll then be 60 gr negative which is pretty close to neutral.  

The difference in salt water would be about 3% of the volume displaced, so it should be pretty small.  If you have the weight in air, subtract the weight in water that is the weight of the water displaced, then add 3% to that figure and you will have the weight of sea water displaced.  Weight in air - weight of water displaced = weight in water.

[TimG 62]

1 hour ago, ChrisRoss said:

That may well work, but just looks so bulky to me! 

If you take off the 5"arms/floats you'll drop 180 gr x 2 = 360 gr buoyancy then replace them with INON mega floats - small size which are 390 gr buoyancy each that will add 420 gr of buoyancy to the rig.  You'll then be 60 gr negative which is pretty close to neutral.  

Yeah, Chris is right, it does "look" bulky but when you actually handle the system, it really isn't.

I tried the Inon Mega Floats in size M. Got to say I hated them. They are REALLY bulky! 

[ChrisRoss 150]

Just now, TimG said:

Yeah, Chris is right, it does "look" bulky but when you actually handle the system, it really isn't.

I tried the Inon Mega Floats in size M. Got to say I hated them. They are REALLY bulky! 

The size S are much less bulky,  I have a pair on my rig - the two of them is enough flotation for my rig.   It looks to me like the crossbar float would interfere with my site line over the lens port which I use to help aim.

[gradient 1]

Thank you gents. Depending on the application, I might just end up buying and trying both setups. I like Tim's as I think this would add a bit of a trimming effect on the rig, as it also feels a little bit pointing upwards by the port side due to the port float. I like to have the INON's though, they're currently 30% off at blue water photo  

 

[divengolf 17]

Interesting discussion. I take a different approach to achieving neutral buoyancy. I've built a small frame out of 1/4" polycarbonate that I attach to the bottom of the housing via the 1/4" female thread. Then I attach links of 2 " PVC pipe capped on both ends to the frame using tie wraps. This allows me to adjust the buoyancy by changing the length/number of the PVC pipes. I fine tune the rig to get about 1/2 # negative in fresh water at home which is about neutral in salt water.

The major advantages are that it's easy to make buoyancy changes when needed and that nothing gets in my sight line. The major disadvantage is that it adds about 3 inches to the bottom of the housing, so getting down into the sand is sometimes a bit of a challenge. I use this set up mainly for macro as I remove two 14 " buoyancy arms from my strokes when I go from dome port to flat port.

Another advantage is that it's real cheap. I have less than $10 USD in the setup.

Just another approach.

Edited April 9, 2021 by divengolf

[gradient 1]

31 minutes ago, divengolf said:

Interesting discussion. I take a different approach to achieving neutral buoyancy. I've built a small frame out of 1/4" polycarbonate that I attach to the bottom of the housing via the 1/4" female thread. Then I attach links of 2 " PVC pipe capped on both ends to the frame using tie wraps. This allows me to adjust the buoyancy by changing the length/number of the PVC pipes. I fine tune the rig to get about 1/2 # negative in fresh water at home which is about neutral in salt water.

The major advantages are that it's easy to make buoyancy changes when needed and that nothing gets in my sight line. The major disadvantage is that it adds about 3 inches to the bottom of the housing, so getting down into the sand is sometimes a bit of a challenge. I use this set up mainly for macro as I remove two 14 " buoyancy arms from my strokes when I go from dome port to flat port.

Another advantage is that it's real cheap. I have less than $10 USD in the setup.

Just another approach.

hey thanks for the reply! Would you mind sharing a picture of that setup? I have looked into doing some DIY work to achieve neutral buoyancy too. I think doing it yourself saves money, but more importantly allows you to have full flexibility just by using simple home hardware materials. 

[mcgowman 1]

TimG,

Why do you recommend the triple clamps with the cutouts?  Better strobe positioning options?  (Sorry if I missed it, long day.)

Thanks much.

[divengolf 17]

Gradient,

give me a couple days and I'll get a pic together.

Harry

 

[Davide DB 486]

13 hours ago, mcgowman said:

TimG,

Why do you recommend the triple clamps with the cutouts?  Better strobe positioning options?  (Sorry if I missed it, long day.)

Thanks much.

Yes, without the cutout you cannot move the arm forward: the arm stem near the ball would hit the clamp.

[TimG 62]

14 hours ago, mcgowman said:

TimG,

Why do you recommend the triple clamps with the cutouts?  Better strobe positioning options?  (Sorry if I missed it, long day.)

Thanks much.

Just as Davide explains. Without the cutouts you can't push the strobe arms forward. It's not obvious until you find you can't do it without the cutouts! (Been there, learned that one!)

[Davide DB 486]

5 minutes ago, TimG said:

Been there, learned that one!

Sad but true. I still have it without cutouts and I still swear sometimes!

[Draq 118]

I like what Tim showed and have seen that idea used before.  I attach a computer to the camera also and that provides a nice place to do so.  However, I also have found that if I need massive lift, the big Nauticam carbon arms help.  They are about 650 gr each.

I am not sure, but I suspect because of the mounting ball for a focus light, the location of the fiber optic bukhead and the need for access to the vacuum button, I don't think the extra arm over the housing would work. 

On the other hand, I do have a rope handle  that I use to hand up the rig to the boat and I have wondered about finding a way to attach a couple floats to each end of that.  I normally stow it while in the water, but there is no real reason for that.  A couple of zip-tied Stix floats of whatever size is needed  should add up to 360g flotation and is easily removed.

 

 

[Davide DB 486]

4 minutes ago, Davide DB said:

Sad but true. I still have it without cutouts and I still swear sometimes!

To be honest: I swore. I used the horizontal float arm as @TimG until I bought an external monitor

 

 

Whit the external monitor I had to find a different solution (a good trimmed gear is like a sail boat: weight on the bottom!).

I used two small floating arms from Flexarm in which you can remove the 1" ball. Now I can move the arms even without cutouts 

 

 

 

 

[TimG 62]

1 hour ago, Davide DB said:

Sad but true. I still have it without cutouts and I still swear sometimes!

I hear ya!

[TimG 62]

49 minutes ago, Davide DB said:

To be honest: I swore. I used the horizontal float arm as @TimG until I bought an external monitor

 

 

Whit the external monitor I had to find a different solution (a good trimmed gear is like a sail boat: weight on the bottom!).

I used two small floating arms from Flexarm in which you can remove the 1" ball. Now I can move the arms even without cutouts 

 

 

 

 

Wow, not see that before. A very neat solution and those Flexarms are good indicators for a boat crew where to grab the system

[Davide DB 486]

Yes, I took the idea from Aquatica floats I saw on several BTM video. They weren't readily available here in Italy so I found a similar solution