Weight of Photo rig alters trim?

[ozziworld]

I use no wet suit, 8lbs on my weight belt, SP Jacket BC. When neutral my BC is totally empty of air when I am at 500psi on an Alum 80. Without the photo rig, my horizontal trim has been good.

I have been diving the exact same rig for at least 10 years and have never found trim to be an issue.

With the recent introduction of housing and strobe (FIX S90 and INON S2000), When doing WA I did not notice any change . The rig is negative. My guess would be about 3lbs negative.

I just recently started trying to do Macro Photography more intently and found my legs tend to float more now when doing macro and harder time trying to stay horizontal. When I totally empty my lungs I do manage to get my legs to sink.

I am guessing the additional weight at the front from the camera rig might be shifting my center of gravity too far away from the weight belt and thus leveraging my legs upwards.

Do I just add weight to my weight belt? I don't want to go to ankle weights.

Am thinking being slightly negative would be helpful when doing Macro.

Also thought good excuse to buy SP Jets in place of my old Mares Avantis

Any thoughts? Advice?

 

[bvanant]

The best answer is to judiciously add flotation to your camera rig to make it just very slightly negative. No need to do anything to your weights, fix the camera.
Bill

 

[ozziworld]

Actually thought of adding float arms and stuff but that would also add a lot of bulk. The ULCS float arms aren't buoyant enough to make the FIX s9o neutral. I think at best they might just add 6 ounces of positive buoyancy - not enough.

 

[Nemrod]

The FIX90 is a portly little tank of a rig but I really don't notice it underwater. My legs sink like boat anchors and I now suspect with the inclusion of a titanium rod and some other assorted hardware it can only be worse. I now look like the (x-rays of) kid in the movie Kicka-s. In fact, don't take this the wrong way, exercise does wonders for shifting the trim rearward.

I dunno, try shifting your tank rearward or adding a little weight on the belt, a little. Since I often dive without a BC, I actually include the weight of the camera in my mental calculations. In any case, even if I had to ditch the camera, the difference is not enough to ruin my day, more so than having ditched the camera already, bummer, if that were to happen.

N

 

[ozziworld]

I'll be the first to admit that I could definitely use some exercise. I guess one can tell my general fitness with the amount of weight on my belt given no wet suit I have. Over the years I have added four pounds to my weight belt and a lot more around my waist

Anyway, I did not feel that the introduction of camera rig would figure-in to having to add or redistribute my ballast.

I posted here just to see if others had similar experiences. Am thinking of just adding weight to my belt and see how that works. Might add some weight to the bottom of the tank since that might be leveraging me upwards when as it is emptied.

 

[AussieByron]

I dive without wearing a wetsuit (board shorts and sharkskin long sleeve) and with a Ally BPW. I find that this distributes the weight more evenly over my back instead of all the weight around your waist with a weight belt. For fine tuning I sometime add small weights to the tank straps.

When I dive with my Dslr I did notice that there is a difference in trim. I have added Ulcs buoyancy arms to take some weight out if the system which makes a big difference.

Now when I dive with my camera I simply take off one of the small trim weights from the tank strap.

Hope this gives you some ideas

Cheers Mark

 

[scuba e]

Has your body profile changed at all? If your legs sink when you exhale that seams odd. Your lungs are forward of the weight belt. that should be the point of pivot. Have you changed fins? New booties?
My rig is slightly negative with the macro port and slightly positive with the dome. Because I wear booties I find with the macro rig, If i am head down to get the angle I want, I may need to pull my knees up towards my core. that takes away from the effiency of lift the booties give my lower body.
Also, you mentioned this is mostly with macro. When i was shooting point and shoot macro it required pushing the camera way out from my core to get the lens as close to the subject as possible. If your rig is negative then this is exagerated by giving more leverage to the negative effect. ( the exact opposite of my booties)WIth the DLSR's the working distance for macro is generaly much futher and in most cases your face is right on the camera view finder so the effect of negative ballast is minimal. You may jsut need to keep your head closer to the camera.

 

[ozziworld]

scuba e,

That is exactly what is happening. The added weight way up front swings that part of my body down. I think I just did not have anymore weight on my belt to off-set any changes and the differences are felt when something different is added to the mix.

 

[Nemrod]

When at rest (or even underway), pull your lower legs up behind you, should be there anyways. Use a modified frog kick to keep your lower legs high and tucked up and off the reef. This will help prevent sinking legs as well as floaty legs. Extend the legs slightly to alter trim as needed. Use the flutter/scissor kick in the open water column and surface to get from A to B. If you are diving an aluminum 80, as they empty, in particular, they get light on the tail, use a steel tank or add a trim weight to the tank.

Good luck, loose a little of that belly weight and it will do wonders for your trim, just a general observation, men need to loose belly weight, women need to loose, uh, weight from their caboose. Adding lead to offset a body problem that can be easily reduced is avoiding the real issue. Not aimed at anyone in particular, just a general observation of divers at large or in the large.

I usually carry my camera gripped below me and then swing it forward and up and out to shoot.

N