Diving doubles and drysuit trim

[alanchang]

Hi Guys,
I am diving HP100 doubles with 5 lbs of tail weights. Also, I'm wearing a dry suit, using a DIR BP/W and stainless BP. I'm 5 ft 9. I'm using Scubapro jet fins.

So the thing is, I can stay trim only if I shift a lot of air to my upper body and my arm/dry gloves. However, I can dive this way comfortably and stop in the middle of the water column with minimum fin movement. If I dump the gas from my arm or let a lot of air go into my leg, I become head heavy. If I dump all the air from my drysuit, I also become head-heavy. I have been diving this for a long time. Is this normal? I thought I had to be very balanced with no air in the suit, and am I really supposed to use the air in my dry suit to adjust my trim? I do feel a bit more comfortable being a bit head up (15 degrees) when doing things like a gas switch, valve drill or deco tank take off/replacement.

The problem is, sometimes ppl frequently bump into me, and since I adjusted my trim using the drysuit air position, I could lose my trim and needs to readjust after.

 

[PEDiver]

Where are the bands on your tanks positioned? Where do the tanks rest on your back? Some of the issue could be band placement or how you have your harness/BP setup. I wouldn’t say it’s normal for you to have to pump air into your upper body to stay trim. I can generally trim out fine without any air in my drysuit with both steel and aluminum doubles. But I also dive LP85s vs HP100s so I am not as familiar with how the weight is distributed in those tanks.

 

[alanchang]

Where are the bands on your tanks positioned? Where do the tanks rest on your back? Some of the issue could be band placement or how you have your harness/BP setup. I wouldn’t say it’s normal for you to have to pump air into your upper body to stay trim. I can generally trim out fine without any air in my drysuit with both steel and aluminum doubles. But I also dive LP85s vs HP100s so I am not as familiar with how the weight is distributed in those tanks.

Band: As high as possible, upper band on the neck of the tank
Placement on BPW: As low as possible, on the lowest hole.

 

[PfcAJ]

You probably need to loosen your shoulders and tighten the crotch strap a bit.

Your suit needs to have enough gas to loft your undergarment. No more. No less.

 

[inquis]

If your wing has multiple positions, put the lowest holes on the posts (making it as high as possible).

My advice is to use your suit less and your wing more. This will increase your stability (less air moves around when you tilt up/down while diving) and combat the head-heavy tendency (keeping air up high). Just enough air in the suit to eliminate squeeze, but you should still feel pressure. If you feel an air bubble move around when you roll left/right a bit, that's too much.

 

[rjack321]

Is your dive count accurate?
Your suit sounds overfilled with gas...
When your tanks are near empty are your suit and wing empty?

 

[alanchang]

You probably need to loosen your shoulders and tighten the crotch strap a bit.

Your suit needs to have enough gas to loft your undergarment. No more. No less.

I'll try

 

[Nick_Radov]

Trim is an individual thing with a zillion variables so you might have to experiment to figure out what works for you. If you're head heavy then try replacing your steel backplate with an aluminum or carbon fiber one, then put the equivalent lead on a weight belt.

 

[DeepSeaExplorer]

Head heavy usually means the shoulder straps are too tight, which is a common problem. Also, there shouldn’t be a lot of air in the suit, just enough to ease the pain of suit squeeze and no more. At the end of the dive, on your deco/safety stop, pump up the suit for comfort.

 

[crofrog]

I'll try

Go as low as you think you possibly can, then go a bit lower. Make sure the tanks are in the bands as low as possible too you have to slide that rig down your back.