I seem to be swimming downwards...

[MinimalMayhem]

I know this is a tricky problem to diagnose over the interwebs, but perhaps someone has had similar and has a magic bullet...

I'm on CCR (manual) and when swimming everything seems fine - I'm mostly in caves/mines doing frog/modified frog and keep position above the floor nicely. The problem I seem to be having is that when I stop swimming, for a tie off etc. I find I'm actually slightly positively buoyant...not always, but often enough for it to be a bit puzzling.

Yesterday I spent ages during a dive stopping while swimming to make sure I wasn't positive but then found while swimming I sometimes was heading down towards the floor. Very frustrating.

I've got a couple hundred hours on mccrs, so it's not like it is a new kind of diving. But this drifting upwards I've only really noticed in the last year or so.
Kit has been similar, though I am now on a sidewinder rather than triton and I'm diving a 2mm O3 neoprene suit rather than a trilam. Depths are typically in the 10 -20m range. In the past I have been told I tend to swim a bit head down, but find that if I lift head up etc. I start swimming upwards!!!!

Am I just rubbish and need to practice more or what?

[notdeadyet]

Have you tried dialling down the O2 flow rate? When you stop moving you burn less O2 so there will be a gradual increase in buoyancy. Or maybe the flow rate has drifted too high over time? Dwyer flowmeters are pretty cheap and reliable if you don't have one.

[JonG]

Jas, will check next time but maybe cyl and cans are acting like hydrofoils making you think buoyancy is correct when it's not, if so this makes you a submarine which is pretty cool.

[MinimalMayhem]

oh dear, the answer seems to be pretty mundane and sadly not a submarine ��...had a decent go on couple of dives at diagnosing it and I think it is as simple as overcompensating for being tail-heavy. I think I put a sniff too much gas in my suit legs, which gives me just enough tilt that swimming forwards I'm counteracting the excess gas...when I stop that excess very slowly brings me upwards.
In my (admittedly weak) defence, using drysuit only for buoyancy is relatively new to me