Problem with trim using doubles

Denver · Jul 23, 2002

I recently switched to doubled PST HP 100s and cannot maintain trim at all. Here is the setup.

Drysuit
AUL SS Heavy BP and wings
Double HP 100s
No weightbelt

The problem:

My center of gravity is to far forward (high on my body). When trying to maintain horizontal the air in my DS goes to my feet and I end up inverted. I remain fairly neutral when this happens. I have tried using 2 sets of ankle weights which helped but did not totally correct the trim problem, but the use of ankle weights is not acceptable.

Would gaiters fix the problem? I have tried using the DS as my primary BC and just putting in enough air to take the squeeze off. Pretty much the same results either way.

I have the doubles bolted to the top hole in the BP. Would moving it down (about 2") help?

BTW I have no problems with a single AL80.

Thanks
Paul

WreckWriter · Jul 23, 2002

Do you have your doubles slid as far down in the bands as possible? I keep mine just past the tank shoulder, on the first available pieces of straight tank.

Since you're diving dry gaitors might help. Do you feel that it's an air movement issue or just tank balance? Ankle weights are bad for sure.

On my aluminum doubles I took a v-weight, cut it in half and just use half of it on the bottom bolt. That helps me stay trim and provides the tiny bit of weight that I need. With steels I don't know that you'd want to add weight.

I'd try adjusting tank position first. Just be sure you can still reach your valves.

Tom

trheeltek · Jul 23, 2002

Originally posted by Denver

My center of gravity is to far forward (high on my body). When trying to maintain horizontal the air in my DS goes to my feet and I end up inverted. I remain fairly neutral when this happens.

If you're neutral, you could always just dive inverted : ). Ok, maybe not.

I helped a friend with this problem, diving dry with double LP104s. Gaiters and an AL. backplate to reduce weight helped a lot in his case; the bands were already just below the tank shoulder. We also played with weights on the tanks to move the center of balance, but that didn't work well.

FYI, I've heard that the HP100s are a bear to get right since they're so short and therefore put the weight too far forward. Good luck with it, hope you find the sweet spot.

WYDT · Jul 23, 2002

Originally posted by Denver
When trying to maintain horizontal the air in my DS goes to my feet and I end up inverted.

It sounds like you've got too much air in the suit. You should have as little air as possible in it. Use the BC for buoyancy and just a small squirt of air every 30ft or so in the suit to soften the squeeze (note: not eliminate it). If you can feel air in your feet you've got too much air in the suit.

DSAO!!

Bottomfeeder · Jul 24, 2002

The heavy backplate is a problem. Do you have a wing with more than one set of holes? If you do, try using the bottom holes. As others have suggested, move the tank bands as high as you can.

CincyDiver · Jul 24, 2002

Originally posted by Bottomfeeder
The heavy backplate is a problem.

I am in the market to get a backplate and I have been trying to figure out if I want to get an Al or SS backplate. I was under the assumption that a heavier SS backplate was a good thing when diving with a dry suit. Are the doubles adding too much weight then? Sorry to get off topic here.

Denver · Jul 28, 2002

Finally able to get out and try the suggestions offered. I put less air in the DS and was able to take one ankle weight off. But I was somewhat chilly in 48F water.

When I tried to change the BP/Tank setting I discovered that I had put the lower band in the lowest hole on the BP with the top band in the top hole. I'll have to try that suggestion next time.

Thanks again.
Paul

Denver · Jul 28, 2002

Double post. Sorry.

detroit diver · Jul 30, 2002

Originally posted by CincyDiver

I am in the market to get a backplate and I have been trying to figure out if I want to get an Al or SS backplate. I was under the assumption that a heavier SS backplate was a good thing when diving with a dry suit. Are the doubles adding too much weight then? Sorry to get off topic here.

Hi Chris,

I dove with a SS backplate and double LP104's until a couple of months ago. I couldn't get my feet to stay down after purging my drysuit. I tried a weight belt to bring my hips down, but that was just overweighting. What was happening was that there was too much weight too high up on my body, and the fulcrum just forced my feet to compensate.

I switched out my backplate to an AL plate from FredT and have been very happy since. First of all, I didn't need the extra 5 or so lbs to carry around. And I didn't need the 5 or so lbs of bouyancy to offset it. My balance and trim improved greatly.

If you've got an AL plate to borrow, do yourself a favor and try it. I think you'll like it.

Jack

DPS2 · Aug 11, 2002

I, too, am having a problem maintaining my trim... except that for me, my feet always want to sink. I am a big guy (6'1"/225#) with a fairly athletic build - broad shoulders, etc. I am assuming that my upper torso is displacing more more water than my lower torso and is therefore throwing my buouancy off. I moved my tank bands lower on my tanks (double PST104's) which helped, but I don't want to get them too low.... Are there any other "big" divers out there that have the same problem? How did you fix it? By the way, it doesn't matter if I dive wet or dry (although I can control it better when I am dry). My fins are Scubapro Jet Fins which are quite negative, but I refuse to give them up! Any ideas are greatly appreciated!

Problem with trim using doubles

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