Does a scooter count as 'redundant buoyancy'?

[bipolarbear]

In a real emergency I would ditch what I could do without. No equipment is worth my life or in other words: when I'am dead that equipment won't be of any use to me.

So the real question here is: at what depth do you plan to ditch what and can you still get up? If so, no problem as far as I'am concerned. I do not believe in strict protocols, but doing what works. A drysuit alone is no guarantee either you can make it to the surface with all your gear.

This is a really tough question, and one I've thought about but never really planned any procedures for.

On a dive like today, 80m, if I had hit my inflator at 70m and the wing failed, I would have thumbed the dive, pointed my scooter up, and ascended. I would have used the scooter to maintain my position in the water column during any mandatory deco stops.

The situation would be much worse if it was a square profile and the wing failed at say the 15 minute mark after considerable time spent at 80m. I would have considerable deco at that point. I think I could still use my scooter, but it would be difficult, and my stops would definitely be sloppy.

What about if the wing failed AND the scooter failed? That is a bad day indeed. I like to think I could deploy one or both of my SMBs to achieve positive buoyancy, which on my calculations would be ok, but if would be a total **** show in reality. I'd inevitably have to clip an SMB to my harness to do bottle rotations and gas switches. It would be awful. I like to think I would probably make it out without getting bent.

 

[chrisch]

I've never owned a lift bag and it sounds like I should look into one. The SMB approach is clunky. Can a lift bag be stowed in the pockets of tec shorts, or is it too big?

The devil is in the detail. A dSMB can give some bouyancy - of course - the issue being how much and how much you need. A lift bag is not going to be substantially different. Both these options have the problem that you can use up quite a bit of gas adjusting the lift to get a slow controlled ascent. A drysuit is much easier to (ab)use for that task.

If you are diving 80m after 300 dives you have not enough experience to either argue the other person was wrong (which they were IMHO) or that you have the what-if knowledge based on stuff going wrong in the past.

I hope the discussion gives food for thought and it is good you have opened it out to accept suggestions and wider opinions.

 

[bipolarbear]

The devil is in the detail. A dSMB can give some bouyancy - of course - the issue being how much and how much you need. A lift bag is not going to be substantially different. Both these options have the problem that you can use up quite a bit of gas adjusting the lift to get a slow controlled ascent. A drysuit is much easier to (ab)use for that task.

If you are diving 80m after 300 dives you have not enough experience to either argue the other person was wrong (which they were IMHO) or that you have the what-if knowledge based on stuff going wrong in the past.

I hope the discussion gives food for thought and it is good you have opened it out to accept suggestions and wider opinions.

Thanks for this input. No debating that a drysuit is better as redundant buoyancy than eff-ing around with lift bags and / or SMBs.

As to your remark about my experience, no arguments there. I launched into tec diving hard and fast, doing my AN/DP/Helitrox at the 50 dive level and then completing Advanced Trimix and Advanced Wreck at around 100 dives. I acknowledge I am absolutely a 'beginner' when it comes to this stuff, but I try and take a risk-averse approach to my diving, have an intellectual interest in the physiological aspects of decompression diving, and have had a few scares in my short diving career (including what I feel was a 'near death' one in a wreck recently) to push me far into the conservative zone with future dives.

 

[Capt Jim Wyatt]

For planning purposes: NO

IRL if everything else goes to hell: Yes

 

[Gone for diving]

I've never owned a lift bag and it sounds like I should look into one. The SMB approach is clunky. Can a lift bag be stowed in the pockets of tec shorts, or is it too big?

My diverite 50lb open bottom lift bag.



| 50/140LBS Scuba Diving Lift Bag Cave Wreck Diving Salvage Refloatation Gear Equipment with Over Pressure Valve

50/140LBS Scuba Diving Lift Bag Cave Wrack Diving Salvage Refloatation Gear Equipment mit Überdruckventil - AliExpress 18

Smarter Shopping, Better Living! Aliexpress.com

a.aliexpress.com

 

[bipolarbear]

My diverite 50lb open bottom lift bag.
View attachment 864617
View attachment 864618

| 50/140LBS Scuba Diving Lift Bag Cave Wreck Diving Salvage Refloatation Gear Equipment with Over Pressure Valve

50/140LBS Scuba Diving Lift Bag Cave Wrack Diving Salvage Refloatation Gear Equipment mit Überdruckventil - AliExpress 18

Smarter Shopping, Better Living! Aliexpress.com

a.aliexpress.com

This thing is tiny. Thank you. I will add it to my gear, I have space and 50lbs of lift is huge.

 

[johndiver999]

I would think that a smaller smb(s) that would be completely filled at depth (with over-pressure valves) and clipped off, would provide a manageable and uniform amount of lift,

A 50-lb lift bag would be a hand full and would be expanding on ascent, so would require frequently and timely attention, unless you plan on sending it to the surface and winding yourself up a reel?

How much lift max is required?

 

[justinthedeeps]

Probably the immediate answer to your debate is a drysuit.
The wisest deep divers in SE Asia seem to go that route and seem to cope with surface heat.

But want to be some metres deeper without venting any gas? Just scoot there.
Want to bump up a few metres shallower without swimming there? Scoot
Counter a sinking situation, loss of wing, or a mild downcurrent? Scoot scoot

Should you need it? No
But you don't need fins, either? [at least according to latest showoffs]

 

[PfcAJ]

I mean, if my wing failed I can point my scooter to control my buoyancy. It has plenty of power, plenty of battery life, and could easily propel me upwards even on a dive with 3+ decos or stages.

I can swim up my doubles with a wing failure. I use stiff Jet fins and am relatively fit. But I suppose the concern is that if your wing failed at 10m during the descent on an Advanced Trimix-level dive, you wouldn't realise until you hit your inflator at the planned depth and I know there's no way I can swim up with full tanks in that configuration.

I understand the risk with double bladder wings which is why I have avoided them to date. If I did dive with one, I would of course dive with the second inflator valve disconnected.

Ditch the heavy tanks and you’ll be very close to neutral. Trimix is light, and a single tank of oxygen or 50% doesn’t weight much at all.

 

[grantmac]

With AL tanks and a balanced rig I think you're alright (I say from a few steps behind you). A full 6' DSMB should be more than enough to get you to your O2 stop as you drain tanks.

That said I'd consider attaching a 50# lift bag to your scooter. Less to save you and more to save it in the event of a flood.