Multiple 25 foot drills in a row???

[PfcAJ]

Practice from 15 ft hovering and due to just a small amount of expansion you should be able to pull the SMB back down without going up repeatedly. We do this while training people to deploy an SMB.

^this. Just yoink it back down.

 

[Superlyte27]

The "Double Ender" trick is to put a Double Ender onto your line. Then let out 3 or 4' of slack... The double ender keeps the slack tight so line isn't blowing all over the place. It's simply weighted straight down. Now, inflate your bag as hard as you can.... you'll watch the double ender start to move up towards you taking out the slack. Grab and unhook the double ender and clip it back to your d-ring. Piece of cake until you get really proficient.

 

[guruboy]

I'll have to try that next time im practicing. Thanks for the tip.

 

[beanojones]

The "Double Ender" trick is to put a Double Ender onto your line. Then let out 3 or 4' of slack... The double ender keeps the slack tight so line isn't blowing all over the place. It's simply weighted straight down. Now, inflate your bag as hard as you can.... you'll watch the double ender start to move up towards you taking out the slack. Grab and unhook the double ender and clip it back to your d-ring. Piece of cake until you get really proficient.

Oh to occasionally dive with divers that can dive!!

Tricks like this are out there, but when teaching I never get to steal other people's tricks because I never get to see them.

 

[gizmo1972]

DCS affects people differently i have had 3 mates teaching ow sitting on the platforms doing drills then doing CESA for 6 students all in all he did 10 partial ups and 6 full downs 6 full ups and then spent the rest of the day in the chamber!!!
if your going to do smb deployment tie a line to the top then you can vent it annd pull it back down
chamber runs arnt cheap or fun!!

 

[beanojones]

if your going to do smb deployment tie a line to the top then you can vent it annd pull it back down
chamber runs arnt cheap or fun!!

The problem is for someone working out SMB deplyment that extra line is an extra bit of "must get right".

I'd go with the "trade places with someone who wants to also do a bunch of SMB practice" Each spend 20 minutes under and the other spend 20 minutes up top, then swap. Wash rinse repeat.

(Agreeing with the CESAs are a problem idea, and that at least would give me pause to do a nuch of runs to the surface.)

 

[supergaijin]

Plan it out on tables and see what it says....
Oh wait, tables don't go as shallow as 25'. Hmmm, must be a reason for that. I wonder what that reason is.

Watch your ascent rates, and you got nothing to worry about. As long as your ears don't get tired of clearing, you can do it over and over indefinately.

I'd be wary of following this advice. People (usually instructors) do get DCS from mulitple shallow ascents ie. while performing multiple CESA's.

I don't think there have been any studies for multiple ascents like this. The ratio is good according to Haldane's 2:1 ratio theory. However AFAIK his experiments didn't involve multiple decompressions. Decompression theory has moved on from the early 20th Century of course. Nowadays some people take more and more notice of the Tiny Bubble Group which believes 'silent bubbles' may in some cases turn up the volume to give you DCS. Silent bubbles are increased by effort- multiple ascents involving 'effort' is not a good combination IMO.

A few ascents will not be a problem. Personally however I try to avoid them as much as possible. I certainly would not advocate that you can do them indefinitely without risk.

 

[Tortuga68]

Not a very scientific approach to the problem, lol

The best example I have was when I was working as a commercial diver in a Dam. My job was to tie the crane to the submerged tree and pull it out. I followed the trees up over and over and over, literally 100 times per day for a solid week. The tender would unhook the tree on land, and the crane operator would put the cable back in my hand, for me to go back down and tie it to another tree. Wash, rinse, repeat

This is not scientific either. You'll find anecdotal evidence to support both cases (no problem vs some evidence of possible DCS). IIRC PADI changed their recommendation for CESA to partial ascents. I once had a little ping in my shoulder after multiple shallow ascents, might have been DCS, might not. Won't be doing it again though.

^this. Just yoink it back down.

Agree, you're practicing deployment more so than ascending. Maybe do one ascent at the start of the dive, multiple deploy/retreive, and one ascent at the end of the dive - that should be enough

 

[Damselfish]

The tables may not go shallow, but they also don't assume multiple ascents in a row. Plus part of practicing this skill is that you're maybe going to screw up sometimes and get caught and pulled up or something. So how lucky are you feeling?

Personally I wouldn't do it. I would pull it down - just work with a partner who can dump the air from it on the surface if you want to practice with something too deep/too much air to pull down.

 

[beanojones]

IIRC PADI changed their recommendation for CESA to partial ascents.

Unfortunately this is not the case.

There's a reason other than it's a pain why people don't like teaching OW.