View Full Version : Delayed SMB
I have a question concerning the issues surrounding the deployment of delayed SMBs.
Other than 'train in the use of your equipment', which is unfortunately what I have found on the reports of the Incident Reports, are there recommendations regarding the deployment of a delayed SMB in respect to 'when'. I have my own views on this, which may or not be valid, but what worries me a little is that I have so far failed to get a concensus of opinions from the various diver friends I have asked recently. Some will always deploy before leaving the bottom or before making the ascent from wherever ascent starts, others will deploy in mid water somewhere during the ascent.
Having been out of the 'training circuit' for some time, can someone illuminate me as to what is current advice/training practice as opposed to what is the subjective preference of one or the other diver.
Thanks a lot
Jeanne
edward haynes
10-09-2003, 21:26
Jeanne
From the BSAC 2002 Instructor Manual:
Sport Diver open water lesson 04 - Be competent and confident in their ability to: 1/. Deploy a DSMB 2/. Ascent using a DSMB 3/. Conduct a decompression stop using a DSMB.
Diver Leader open water lesson 01 - Be competent and confident in their ability to deploy a DSMB from mid water whilst controlling their buoyancy.
HTH
Edward
Chris Cherrington
11-09-2003, 09:27
>is that I have so far failed to get a concensus of opinions from the various diver friends I have asked recently. Some will
Mmm... I fear there will be no concensus Jeanne. I recently bought a new DSMB - they come with about 15m of line so they are intended for mid-water deployment on all but shallow dives perhaps??
They best ascent is back up the shot line. If you miss it then you "need" another visual reference point. Clearly from the bottom is best, but you need a reel with enough line to do this. My DSMB has 9m of line - enough to do stops if I miss the shot. I would take a reel plus DSMB if I "expected" to do an ascent on it for some reason - big wreck etc.
I suggest go with your own views - if you are happy with them - and don't worry about what is "correct" - your common sense will tell you if you are off-message! Your experience will tell you what works.
Dive safe.
Chris
Nigel Hewitt
11-09-2003, 09:57
I can't comment on training only practice...
I fear there will be no concensus Jeanne.
Agreed. Different dives require different methodologies so a dogmatic rule will never work.
I recently bought a new DSMB - they come with about 15m of line so they are intended for mid-water deployment on all but shallow dives perhaps??
That's frankly your choice. Most shops have more than one reel in stock. I have 50m on the primary reel/DSMBi and 21m on a spool on the spare DSMB stuffed in a pocket. They are just what I chose to buy not some magically *correct* value.
The best ascent is back up the shot line. If you miss it then you "need" another visual reference point. Clearly from the bottom is best, but you need a reel with enough line to do this. My DSMB has 9m of line - enough to do stops if I miss the shot. I would take a reel plus DSMB if I "expected" to do an ascent on it for some reason - big wreck etc.
Gulp. So last man down bagging off the shot doesn't suit your scheme of things? Most deep water skippers seem to prefer one blob per diver so they can count you off the bottom and then follow you on the tide as you do stops. Hanging on the shotline only really works on neeps and short run times here on the tidal south coast. If the shot is in solidly enough to take several divers hanging on it it isn't going to come up.
I suggest go with your own views - if you are happy with them - and don't worry about what is "correct" - your common sense will tell you if you are off-message! Your experience will tell you what works.
Here we agree. I would recommend going equipped to deploy from the bottom but if that doesn't suit the dive then cut and stick a plan as you go. The only key point is that if you have stated a plan to your surface cover stick to it.
nigelH
Chris Cherrington
11-09-2003, 16:03
Gulp. So last man down bagging off the shot doesn't suit your scheme of things? Most deep water skippers seem to prefer one blob per diver so they can count you off the bottom and then follow you on the tide as you do stops.
Depends on the skipper Nigel - I agree with you here, but our club tend to dive sub 35m and tie off the shot on a light line. A commercial skipper is a different animal to a BSAC diver/cox.
Chris.
derek perry
12-09-2003, 09:39
Jeanne
The other posts are quite right, there will be no consensus and you go with what suits you best. The method I use is to deploy from 10. metres. I do not use a reel. I have 10mtres of 4mm to 6mm thick line wrapped neatly around my DSMB with a heavy karabiner on the end. This is fixed to prevent accidental unravelling and hangs on my BC. The Karabiner also acts as a weight and when I deploy this takes the line down. I then hold the DSMB out while it is filled and as it goes to the surface the line runs through my hand loosely. The advantage of this method is that you don't have flimsy reel line all over the place likely to catch on people. The line is taught under the weight of the karabiner and when deployed you end up with a nice thick line to ascend. When on the surface I either collect the line up to hand into the boat or just hand in the DSMB and the boat crew pull up the 10mtrs of line. I have been using this method for 15 years and have never had a problem.
The only thing is you need to be disciplined in buoyancy while you unravel the line at 10 metres.
Derek
steve swift
14-09-2003, 12:03
I have always taught the following order of preference for ascent:
shot if tidal flow (and navigation!!) permits
2 man deploy DSMB with reel attached to something on the bottom
1 man as above
2 man deploy negatively buoyant kneeling on the bottom
1 man as above
2 man mid water deploy
1 man as above
Plus
Each of the above should be practised regularly
Each diver should have their own DSMD in case of separation
The DSMB should be attached to a reel so you dont have to waste time unravelling line
The DSMB and reel should be attcahed and ready to go in the pocket or wherever to save time
If you use your Primary DV to try and inflate the DSMB you will concentrate so much on that the tsak that you wil lose buoyancy and start off for the surface.
The exhaust method will fill the DSMB too slowly to get a good fill before you have to let go.
IMO if you are in a current and come up from 30+m to 9 or 6m before deploying a DSMB, you could be swept out of sight, especially as the mid water deployment inevitably leads to a poor inflation. As a cox/ DM I like to know where my divers are as soon as I can.
As other posters have mentioned, there are a number of variables in the equation that make a dogmatic approach difficult, but i have found that my approach spares me from getting more grey hairs when i am DM/ in charge of diving operations.
Steve
> The DSMB and reel should be attcahed and ready to go in the
> pocket or wherever to save time
That's just not feasible with bigger reels. My pockets aren't big enough.
> If you use your Primary DV to try and inflate the DSMB you
> will concentrate so much on that the tsak that you wil lose
> buoyancy and start off for the surface.
That needs practice, then. I no longer have a primary DV, but when I did, that was the way I filled the blob.
> The exhaust method will fill the DSMB too slowly to get a good
> fill before you have to let go.
Not true. It's possible to fill one of the AP red blobs (9l? Cna't remember) at 6m without creating a problem. Deploying from deeper is significantly easier. The trick is not to miss with your exhaled gas...[1]
> mid water deployment inevitably leads to a poor inflation.
Not true. This is an important skill - if your divers are getting poor inflation, that is something they need to practice.
Vic.
[1] The trick to not missing the bag is to get your head over to the right as far as you can. And then get it over some more. Horizontal would be good, but not necessary - but you really do need to get your head over much further than you think...
I have always taught the following order of preference for ascent:
shot if tidal flow (and navigation!!) permits
2 man deploy DSMB with reel attached to something on the bottom
1 man as above
2 man deploy negatively buoyant kneeling on the bottom
1 man as above
2 man mid water deploy
1 man as above
Just a couple comments which you can take onboard or ignore as you see fit.
Shotline ascent. Always worth asking the skipper if he actually wants you coming back up the shotline. Some like to take the shot out before the tide turns. Some want everyone on a DSMB so the skipper does not have to run back and forth between drifting DSMBs and the shot. On busy wrecks (like the Kyarra on a Bank Holiday) 100 divers using the same shot is not the best of situations.
As for the preferred method I teach a number of methods and allow the trainee to use whichever they prefer. I like to emphasise that it is a skill you need to be able to do alone as separation is definately a time you will need to make a DSMB ascent.
I would think that your list could be viewed as a progression rather than a preference. Certainly I now almost always send a DSMB hovering in midwater whilst my buddy looks on. Personally I find a solo midwater deploy the simplest and fastest method. Obviously divers need to assess their own competance against the situation, it would be plain stupid to try a mid water solo deploy for the first time from 20m with deco to do.
Plus
Each of the above should be practised regularly
If you can do the worse case compentantly, why the need to practice the others?
Each diver should have their own DSMD in case of separation
Agreed.
The DSMB should be attached to a reel so you dont have to waste time unravelling line
Disagree. There is nothing wrong with using a fixed line. It works particularly well on shallower dives.
The DSMB and reel should be attcahed and ready to go in the pocket or wherever to save time
Disagree. You may want to use your reel for something other than DSMB. You should know how long it takes to assemble and how long it takes to deploy and adjust bottom time accordingly. If you tell the skipper you are diving a 25mins bottom time your buoy should be on the surface at 25mins, not 26mins.
If you use your Primary DV to try and inflate the DSMB you will concentrate so much on that the tsak that you wil lose buoyancy and start off for the surface.
Disagree. You should be capable of maintaining buoyancy while clearing a mask, switchingn regs or deploying a DSMB. Personally I think too many divers think is acceptable to lose buoyancy control as soon as they have to do something else, it simply is not.
The exhaust method will fill the DSMB too slowly to get a good fill before you have to let go.
Disagree. You need two good breaths from anything deeper than 20m. From < 20m you would be better off using a smaller buoy. Personally I will not inflate a DSMB to the point where it is dragging me up prior to letting it go, it is plain dangerous. In fact I prefer trainees to lose the fixation with filling the buoy.
IMO if you are in a current and come up from 30+m to 9 or 6m before deploying a DSMB, you could be swept out of sight, especially as the mid water deployment inevitably leads to a poor inflation. As a cox/ DM I like to know where my divers are as soon as I can.
Aggreed. I was taught that you should always maintain an unbroken and marked route to the surface. A shotline tied to a wreck is a marked route. If you drift off the wreck you need to deploy.
Regards
Matt
nick kay
15-09-2003, 14:51
1. Take a look at the 2002 Incident reports. See how many were due (directly or indirectly) to DSMB usage - frightening...
2. (In an ideal world) each diver should have a primary DSMB and reel and a secondary
3. Get back to the shotline. If you think you won't be able to, then deploy a distance line
4. If you get back to the shotline and you need to get off it (current...), then you need to be able to deploy midwater
5. Learn how to deploy from the bottom:
5a. Reel fastened to the wreck
5b. Double reel with your buddy holding the reels (at worst he has a reel and so do you)
5c. All by yourself
6. As was pointed out to me yesterday "why don't we teach the use of droplines???"
As to where its taught:
a. Ocean Diver, Sports Diver, Dive LEader
b. Advanced Nitrox, ERD
Note however, that some Instructors may never have been taught the use of a DSMB and unless they've gone on to Advanced Nitrox, have possibly never been exposed to the differing methods
Personally (in order of preference):
1. No (appreciable) current - get back to the shotline
2. Fix the reel to something & deploy dsmb
3. 1st diver double reels, 2nd deploys the bag
4. 1st diver reels, 2nd deploys the bag
4. someone doesn't like you, so whatever (safely) works...
iainmsmith
16-09-2003, 10:09
Personally (in order of preference):
1. No (appreciable) current - get back to the shotline
2. Fix the reel to something & deploy dsmb
3. 1st diver double reels, 2nd deploys the bag
4. 1st diver reels, 2nd deploys the bag
4. someone doesn't like you, so whatever (safely) works...
My thoughts are that a good, neutrally buoyant single-handed mid-water deployment is fairly difficult unless practised very regularly. However, if one only ever uses mid-water deployments when needed (everything else having gone wrong) then one will never do it often enough to be able to do it safely.
From this there follow two possibilities:
1) Never do a dive where you might have to do a mid-water deployment.
2) Work up to doing single-handed midwater deployments and once mastered, do them on every dive you do.
Iain
:=Personally (in order of preference):
:=1. No (appreciable) current - get back to the shotline
:=2. Fix the reel to something & deploy dsmb
:=3. 1st diver double reels, 2nd deploys the bag
:=4. 1st diver reels, 2nd deploys the bag
:=4. someone doesn't like you, so whatever (safely) works...
My thoughts are that a good, neutrally buoyant single-handed mid-water deployment is fairly difficult unless practised very regularly. However, if one only ever uses mid-water deployments when needed (everything else having gone wrong) then one will never do it often enough to be able to do it safely.
From this there follow two possibilities:
1) Never do a dive where you might have to do a mid-water deployment.
2) Work up to doing single-handed midwater deployments and once mastered, do them on every dive you do.
3 - get a DSMBi crack off it goes done<1 min :)
iainmsmith
16-09-2003, 11:47
:=From this there follow two possibilities:
:=
:=1) Never do a dive where you might have to do a mid-water deployment.
:=
:=2) Work up to doing single-handed midwater deployments and once mastered, do them on every dive you do.
:=
3 - get a DSMBi crack off it goes done<1 min
Until you discover that you forgot to fill the bottle... :0)
I.
:=:=
:=3 - get a DSMBi crack off it goes done<1 min
Until you discover that you forgot to fill the bottle... :0)
d'oh refer back to previous training on nrmal DSMB release providing your DSMBi is AP Valaves
Chris Tibble
23-09-2003, 20:48
:=:=:=
:=:=3 - get a DSMBi crack off it goes done<1 min
:=
:=Until you discover that you forgot to fill the bottle... :0)
d'oh refer back to previous training on nrmal DSMB release providing your DSMBi is AP Valaves
Which you haven't practised recently because you always use the crack bottle... ;-)
Chris
Nigel Hewitt
23-09-2003, 21:28
>>>3 - get a DSMBi crack off it goes done<1 min
>>Until you discover that you forgot to fill the bottle... :0)
>d'oh refer back to previous training on nrmal DSMB release providing your DSMBi is AP Valaves
>Which you haven't practised recently because you always use the crack bottle... ;-)
I wish...
There was the time I forgot to fill it (The Tompson), the time the valve blew and it went flat on me (Vobster), the time the thread clapped out where the DIN fitting screws into the blob (M2) and last weekend when I had to pinch its O-ring as the one had dropped out of the suit inflation (Black Hawk).
That's this year. I'm getting all to much practice inflating the darn thing manually.
*sulk sulk*
nigelH
John Duncan
26-09-2003, 16:35
AS I see it, you should follow the plan that the dive marshall or Skipper of the boat requires. If the plan is to return to the shot, do that. If the plan is to drift off the wreck, after deploying DSMB then do that. The person in charge of the dive (knowing the site as well as they should do) should know the best way to finish the dive...
JD
Thanks everyone for a very informative and if I may say so, varied account of everyone's preferences and experiences, as well as the learned view. For what it is worth, here is how I approach the subject:
1. Agree in the dive plan the ascent method (back to the shot or deploy DSMB before ascent, or deploy DSMB in mid-water, all will depend on the circumstances, the site, the skipper's expectations, the experience of the buddy, etc.) and agree who's going to do what, and have a back up plan!
2. Dive the plan!
3. I always carry my own reel and DSMB, and I like my buddy to do the same.
4. My preference is, unless the shot is the obvious and agreed ascent method, to deploy the DSMB before ascending. Those reasons are personal I know and not the only option, but I feel much more in control, deploying from a point where I can have better stability (eg. bottom or wreck), have contact with my buddy, in a similar position, in case of something going wrong before ascending, better control of the air expansion (OK, makes diddley squat difference from 10 meters, but you will know that it does from 30 or more, in comparison) or, if deploying along a wall, have visual datum point of potential trouble, such as being pulled up by a jammed reel before ditching. I have always found it slightly odd, and I know this is personal prefence again, to deploy halfway through the ascent unless there is a very good reason for it rather than routine, when potential separation can be a real issue, especially in a tide or poor viz, or limited diving experience of the buddies, and when pressure differences can really take you aback the closer to the surface you get, viz. inflation rate of the saussage. I know we should be trained for all eventualities, and every case and method have their merrits and drawbacks!
Thanks for a good and well approached topic, much appreciated from all of you.
Jeanne
4. My preference is, unless the shot is the obvious and agreed ascent method, to deploy the DSMB before ascending. Those reasons are personal I know and not the only option, but I feel much more in control,
I would say that is the very best reason to do anything. Use a technique which makes you confident.
I have always found it slightly odd, and I know this is personal prefence again, to deploy halfway through the ascent unless there is a very good reason for it rather than routine
The main thing is to know that you can do it when there is a very good reason.
A lot of divers get comfortable sending from the bottom and never move on. Personally I look to improve skills however I can. I used to practice sending DSMBs on drifts, which gets you used to the idea of deploying while floating. Now I find it suits me to deploy hovering above the wreck rather than attached to it. Confidence comes with progressive and regular practice. My latest trick is the one hand deploy, tricky but I am getting there.
Regards
Matt
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