Feeling like a blimp

[bipolarbear]

It's not a streamlining thing.

Because the position of the CL mandates that you keep it close to the hydrostatic depth of your lungs. Some units force you to "wheelie" torso up - so the CL is then at the same depth as your lungs. In flat trim it will be above your lungs and easy to exhale, but harder to inhale. The Revo, the RB80 and the SF2 are all units that tend to promote a torso up position in particular. The knees naturally end up dropping when your torso is 15-20 degrees or more from truly prone.

This is the unfortunate truth. I've just started diving a JJ in stock config and my trim is atrocious. It is just awfully tail-heavy. My instructor recommended converting to a GUE config while trims the unit out properly, but I still have my mod 2 and mod 3 to do and I believe they are required to be completed in stock config.

My solution to the trim issue was to buy lighter fins and just DPV everywhere I dive.

 

[Stoo]

Any thoughts would be greatly appreciated

I'm an OC guy, but many of my friends dive RBs. Some have suggested I convert, but once we discuss the pros and cons, even they agree, it wouldn't make much sense.

FWIW, the guys that come on trips with me where it's 100% recreational diving, just dive OC like the rest of us common folk. Dragging a big unit, and a bailout is IMO, just overkill for this type of diving. Unless you're on a dedicated RB trip, you're likely limited to an hour or so in the water, plus you have all the maintenance hassles and so on. In other words, wrong tool for the jpb.

As for your specific blimpiness, I think it's just the nature of diving rebreathers.

 

[LFMarm]

I'm an OC guy, but many of my friends dive RBs. Some have suggested I convert, but once we discuss the pros and cons, even they agree, it wouldn't make much sense.

FWIW, the guys that come on trips with me where it's 100% recreational diving, just dive OC like the rest of us common folk. Dragging a big unit, and a bailout is IMO, just overkill for this type of diving. Unless you're on a dedicated RB trip, you're likely limited to an hour or so in the water, plus you have all the maintenance hassles and so on. In other words, wrong tool for the jpb.

As for your specific blimpiness, I think it's just the nature of diving rebreathers.

Depends on taste. I don’t mind the prep and cleaning. I have done rec liveaboards where I was the only one in CC and enjoyed it. I could dive much more conservative GFs and also stay deeper longer if there was a reason for it.

 

[mr_v]

My solution to the trim issue was to buy lighter fins and just DPV everywhere I dive.

Don't use equipment to solves a skill issue. If you use DPV everywhere, you will not learn proper kicking and breathing techniques. Also, if you're butt heavy, how do you solve the trim with the DPV? The DPV may compensate buoyancy here and there, but trim is trim. What you probably do now is diving in a seahorse shape while DPV is dragging you around rather ineffectively. Hardly a solution.

You need to spend more time on the unit and proactively work on the trim. With a BMCL setup learn to move air to the legs and feet as you add air to the suit (you're diving dry, right?). Then:

1. Lift your chest slightly to inhale
2. Begin exhaling slowly while initiating a kick and lowering torso; assuming frog/modified frog kick
3. Glide for 1-5 seconds or however long you are exhaling the breath
4. Go back to step 1

The sequence above helps inhalation while moving you to a more horizontal position so that you can glide on the exhale. You'll minimize your cross-section and your movement will become more effective.

 

[Tief*]

Yes, I had the same problem when I first got into CCR diving with OC buddies. I needed to build up more hours on the unit. I also told the buddies we needed to slow the pace down. It was better diving for everyone. Enjoy your journey on the CCR.

 

[bipolarbear]

Don't use equipment to solves a skill issue. If you use DPV everywhere, you will not learn proper kicking and breathing techniques. Also, if you're butt heavy, how do you solve the trim with the DPV? The DPV may compensate buoyancy here and there, but trim is trim. What you probably do now is diving in a seahorse shape while DPV is dragging you around rather ineffectively. Hardly a solution.

You need to spend more time on the unit and proactively work on the trim. With a BMCL setup learn to move air to the legs and feet as you add air to the suit (you're diving dry, right?). Then:

1. Lift your chest slightly to inhale
2. Begin exhaling slowly while initiating a kick and lowering torso; assuming frog/modified frog kick
3. Glide for 1-5 seconds or however long you are exhaling the breath
4. Go back to step 1

The sequence above helps inhalation while moving you to a more horizontal position so that you can glide on the exhale. You'll minimize your cross-section and your movement will become more effective.

Thanks for the advice; I should have mentioned I'm diving wet. I dive in tropical climates, max depth 100m, max runtime 2hrs, so most of the time my 'exposure protection' is tec shorts and a t-shirt! I know that when I dive dry I can move air into my legs to compensate.