New BC - problem with vertical positioning

[Sirto]

I just started using a new rear inflate BC and I'm having an issue with underwater positioning. I'm using a thicker wetsuit than I have used previously and perhaps that's causing part of my problem since I am using a lot more weight than I'm used to (30# vs 18#). My other bc is a hybrid jacket/rear inflate and I don't have this problem with it at least while using the 18# weighting. With the new BC I put 12 pounds in the rear trim pockets and 18# in the intergrated weight pockets. The horizontal trim is good but when I try to maintain a vertical (heads up) position I keep falling foward. Note that I'm talking about under water, not on the surface but the effect is similar to the falling on your face complaint that people often talk about on the surface with a rear inflate BC. I do hover so the amount of air I have in the BC is fine.

One thought I had but haven't had a chance to try out is this. I generally cinch up the shoulder straps pretty tight since that helps give me a good horizontal position during the dive. Perhaps if I loosened the straps and let the bc slide lower on my body it could help. I've also considered adding a tank weight to shift the weight more toward the rear. Any thoughts on these two ideas or any other suggestions would be appreciated.

 

[TSandM]

My suspicion would be that the whole BC is sliding upward on your body when you are vertical, since you aren't using a crotch strap, and that's why you get pushed forward.

 

[Sirto]

My suspicion would be that the whole BC is sliding upward on your body when you are vertical, since you aren't using a crotch strap, and that's why you get pushed forward.

It's not sliding up but rather that I have it cinched up quite high to help give me a good horizontal trim. Perhaps lowering the BC on my body will help the vertical positioning but then I'll be feet heavy again when trying to remain horizontal.

Any other suggestions anyone?

 

[spectrum]

Since you have all of the weight integrated I would not expect the BC to ride up too much. You and the suit will float up into the BC.

I won't ask why you want to maintain a vertical (heads up) position in the water column.

It may be that you are simply top heavy. With 12 pounds of trim weight and the BC running high on your body you are like an upside down bowling pin. For a number of reasons including your situation I would try getting a bunch of that weight down onto a belt or harness. Then put just enough weight in the trim pockets to correct your trim. You can continue to run the BC cinched high if you like it there.

Pete

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[Doubler]

One of the problems with rear inflates is the they tend to push you on your face if over inflated. Get in a vertical position as you normally would and slowly deflate until you maintain vertical. 30# seems like an awful lot to me unless you are diving a dry suit. You may want to ditch some weight if you have problems staying on the surface in a upright condition. Just my 2 cents.

 

[wunat]

Try shifting some of the weights onto the tank cam strap. (Nope this is not the same as having the weight at the rear weight pockets. This should help but only to a certain level (since your system probably doesn't comes with a crotch strap). At first you can simply get 2 weight blocks on a standard weight belt and buckled them on the tank close to where the tank cam strap is.

 

[wunat]

Try shifting some of the weights onto the tank cam strap. (Nope this is not the same as having the weight at the rear weight pockets. This should help but only to a certain level (since your system probably doesn't comes with a crotch strap). At first you can simply get 2 weight blocks on a standard weight belt and buckled them on the tank close to where the tank cam strap is.

I overcome this solution while I was doing some search on this board years ago to counter the face-down effect at the surface. But when my fellow instructors (who's using a back inflation BC) had these problems while trying to do some underwater skills for the students, I asked them to try this. And this worked great.

Hope this helps.

 

[LarryW99]

I have a dive buddy that has similar issue. She has tried all types of weight and BC adjustments. I trust her advice since She has logged over 200 dives to my 25. She has gone to using ankle weights under her wetsuit to get her vertical. Us men do not have the same anatomical problems as do females and weight dispersement. I would suggest putting extar weights on the dock or entry point and try a number of adjustments before. Hope you work it out.

 

[halocline]

It sounds like you need more weight on your back. Get some cam band pockets like the XS scuba ones, and try moving 6-8 lbs onto the cam straps from the front pockets. See how that works. This would somewhat simulate the change in trim if you moved from the AL80 you're now using (just a guess) to a steel tank.

Once you get weight on your back, you'll probably be more comfortable wearing the BC a little lower.

I assume that when you try the hovering mid water in a vertical position, you don't have very much air in your BC, correct? If so, you could almost certainly drop some weight. If your wetsuit is new, a few more dives might help compress it a little and help you get down easier.

Finally, to me it's much more important to have good horizontal trim than vertical, so if you make these changes and you have more trouble hovering motionless in a horizontal position, I'd go back to the old way.