Trouble trimming out with two deco bottles

I've started carrying two deco bottles (Luxfer AL80 with 50% and AL40 forget brandwith 100%) for practicing/training for my normoxic trimix course. At this point, I've only got maybe 8-10 dives where I've carried both deco bottles so I'm definitely still getting used to carrying the extra AL80. Previously, I've only carried my AL40 which I hardly notice anymore.

I've noticed that when I'm diving with two deco bottles I have a lot of trouble trimming out and have to make a consensus effort to stay in trim otherwise I'm almost vertical.

This problem doesn't occur when I am not carrying any bottles or at least if it doesn't it's not very apparent. I sling both bottles on my left side AL40 closest to my body and AL80 on the outside. On my right side, I have a small can light (~-1.5-2lbs) and on left side I also have a small AL6 for suit inflation.

A little background, I'm short ~5'5"-5'6" stocky build but very heavy legs (big calves). Even in wetsuits I am usually always leg heavy which is why I use OMS Slipstreams since they've very light weight.I even wear the OMS Slipstreams with my drysuit. I know that some short people have similar problems trimming out.

I'm diving Double PST 100s, HOG SS backplate, and HOG 58# Horseshoe wing. I moved bands down pretty low on my doubles which should make me more head heavy. I don't think I have much more play to move tanks around right now.

In fresh water, I don't wear any weight at all and find i'm too negative. In salt water I carry 6lbs on a belt. (May actually need a more weight especially when all tanks are empty, especially now that I have the AL80)

One thing I wanted to mention...I've been borrowing a drysuit for the last month and using Hollis F1 fins which I love but unfortunately I find them make me even more leg heavy.

My drysuit was being repaired (zipper replacement) and is going to be returned this week. I am hoping that when I switch back to my own drysuit with OMS Slipstreams that it may help alleviate the problem.

I'm also swapping my wing out for a Hollis C45 donut wing since I find the HOG 58# (love the wing, just find it too bulky) is slightly too big for my HP100s and I experience a little taco making it harder to vent. I've read here and most people seem to think that a donut versus horseshoe wing shouldn't have much affect on my trim?

Anyone have any suggestions? My instructor has been very good with suggestions and critique but I wanted to hear all options and suggestions.

I would have expected you to complain of a loss of trim on another axis, interesting. Do you have any pictures of yourself in the water with the bottles? My guess is that it's something about placement of one or more of your D-rings.

I prefer to put dis-simmilar bottles on a leash to trail behind you. when diving 2 40's I opt for one on either side.
Eric

mathauck0814:

I would have expected you to complain of a loss of trim on another axis, interesting. Do you have any pictures of yourself in the water with the bottles? My guess is that it's something about placement of one or more of your D-rings.

Click to expand...

I forgot to bring my GoPro to film. Next time I want to get someone filming me when I have two stages on.

I'm going to be re-webbing my harness soon anyway so I can re-adjust my d-rings also.

I'm 5'4", and I don't experience the issue you are having, so I don't think it's a height problem. Since both the 80 and the 40 tend to balance a little head-heavy when full, and VERY tail-light when empty, the only way I could see adding them resulting in you being vertical is if you are feet-light and compensating by rearing up.

It sounds as though you haven't quite nailed the trim thing in just the doubles, and I would think it more likely that the problem starts there. I actually found it surprisingly easy to assume additional bottles, once I had my backgas tanks really well balanced.

I find it very normal situation, luxfers are tail light so when you have a full stage your will have more weight pushing on your chest D-ring (you also have another reg there) which will be the same as adding extra 2-3 lbs to you front. this what makes you feel head heavy.

Arching the back helps me as it slightly moves the top of the wing slightly high and more air migrates there.

Could the problem be the oppsite?
I find that whenever I am topheavy (I.e I put a p-weight on my doubles, I get VERY top heavy). This in turn makes me fight against my tanks, and my trim feels funny. Ie, more upright.

If you have pushed your tankes higher toward your head, have very light fins, AND have stages pulling on your front... I think you might actually have the problem reversed.

(I too believed I was bottomheavy.. untill I did my GUE Fundamentalscourse... and found that in fact, I was VERY TOP-heavy)

Just as an experiment, move your doubles to a normal position, place your lead in a tailweight, and put on some heavy fins. (Might be a bit over the top.. but you get the idea...)

TSandM:

It sounds as though you haven't quite nailed the trim thing in just the doubles, and I would think it more likely that the problem starts there. I actually found it surprisingly easy to assume additional bottles, once I had my backgas tanks really well balanced.

Click to expand...

Thanks for advice. I'll try playing around a bit more and see if I'm more head heavy than I realize. I respectfully disagree regarding trim in doubles though. I've been diving doubles for quite a while and have never experienced the trim problem until I started carrying two cylinders. I'm assuming the problem is apparent with one cylinder too but I'm able to easily compensate.

It doesn't make sense to me since both tanks that I am carrying though be tail heavy. I'm hoping it's just a combination of new equipment (used drysuit, used fins, new bottles).

I'll be getting another 3-4 dives this week hopefully with 2 stages so I'm going to try to do a bit more experimenting.

---------- Post added June 15th, 2013 at 09:23 PM ----------

Imla:

Could the problem be the oppsite?
I find that whenever I am topheavy (I.e I put a p-weight on my doubles, I get VERY top heavy). This in turn makes me fight against my tanks, and my trim feels funny. Ie, more upright.

If you have pushed your tankes higher toward your head, have very light fins, AND have stages pulling on your front... I think you might actually have the problem reversed.

(I too believed I was bottomheavy.. untill I did my GUE Fundamentalscourse... and found that in fact, I was VERY TOP-heavy)

Just as an experiment, move your doubles to a normal position, place your lead in a tailweight, and put on some heavy fins. (Might be a bit over the top.. but you get the idea...)

Click to expand...

This thought never occurred to me. I'll try moving my bands up a little more. Perhaps i'm more head heavy than I realize. Thanks for advice.

Macado;

seems od to find this thread as I was trimming out a new set of double LP108's (HP130's) today for a trimix course I'm doing next weekend. whenever I carry bottles I always go nose Heavey and have to compensate with air in my wing and in my dry suit to balance the load back out.

as other have posted. you should try shifting weight down instead of up, also balance your carry load across your body. if I'm carrying deco bottles ill carry my 100% 30cft on my left and my 40cft 50/50 on my right or with a travel bottle the 40 and the 30 on the left and the 80 travel bottle on the right. I was taught to carry the hot bottle to the left ( it's usually the smaller one).

something else to consider is the stage strap and bolt snap placement on the deco bottles. the bolt snaps should be tight against the bottle right up at the neck. this brings the bottles in snug and makes trim easier.

something try.

as for my trim. I try to get a little tail heavey with a full tank and deco bottles, knowing that as I go through the dive it will trim flat with less gas in my doubles and with my deco bottles going light.




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I agree with Imla. I used to think I was tail heavy. I spent sometime just relaxing in trim and my head dropped like a rock. I suspect you are also head heavy and subconsciously way overcompensating.

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