Deco stations and protocols

[Jetsam]

This has been sparked by the debate going on in a recent thread about reels.

As I have seen and used deco stations, this part is based upon my experience of them, these are simple manageable types for 10 divers with a single bar, not a nightmare of wires and poles.

The wreck is shotted, the first divers tie the shot in. The second pair take the station in and tie it at the selected point (usually 21m). There are 2 points to unclip the station, at the tie in at 21m, and higher up incase of a misunderstanding, usually 6m where the station is.
A system of marking the divers in and out is used at the 21m tie in. Commonly a clip or boltsnap that each diver places on the line going down and collects going up. There is another system at the bottom of the shot, quite often a strobe, they not only mark the shotline, but also serve to let the last divers know that everyone is up, so they, as the last ones cut the shot to wreck tie in, the skipper can then collect his weight as soon as the station is detached.

All divers are told that they must get back to the shot. Whether they reel off, or can navigate succesfully, that is their choice. But they must get back. The use of a station is preferable in busy waterways, as it helps the skipper have a less stressfull time, and is generally safer for the divers.

The skipper is under instruction to follow the deco station.

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This is where the debate started with some others. If a diver comes up on an DSMB by choice, it is generally acknowledge that he/she has fu*ked up. If he lost his way back to the tied in shot then it's a fu*k up. If the station has been detached as it is going under with the pull of the tide, and there is still a diver on the wreck "hiding" to "maximise" his/her bottom time then that diver has fu*ked up (sorry MattS, but it's true). There are very few instances where it is not that divers fault. If it's a medical emergency, then shit happens sometimes.

Chasey's reeling up is not something I would do, and I doubt many would, therefore I'm going to ignore Mark Chase. It would be up with the DSMB.

The skipper will follow the station, but if he has to keep an eye on an SMB, then he will as much as he can, but if he loses sight, then he stays with the station. At this point the CG *WILL* have been alerted, and it is possible they would have been appraised of the situation before this point. The skipper has therefore carried out his duty of care.

As to providing a cover boat, most dive boats don't have space for a tender or a second skipper, unless they are really big, but there should be no need, if everyone follows the protocols. Other risk assesment considerations are that you may need to treat the dive as an overhead enviroment, you KNOW you need to get back to the shot, so have adequate reserve/redundancy to complete this.

The divers should ideally co-ordinate their bottom times, and a basic understanding of the tide and how long is sensible to do on the wreck is also useful. Unfortunately too many want to base there dive time upon their available gas and total deco time rather than what would be ideal given the tidal conditions.

At the end of the day diving can be hazardous..... just accept this.

If people don't like this situation, then don't do the dive. It's quite simple really.

Regards

[Mark Chase]

Dispite the fact your ignoring me I agree with everything above appart obviosly from your "Oh Poo" choice of action.

Also if you didnt notice on the previous thread. The diver lost for several hours (not dead) out of Dover returned to his primary tie in and found the shot was no longer on the wreck. The waster had failed / broken than the station loaded with divers had dragged the shot off the wreck and away.

ATB

Mark Chase

This may help some people



Note diver still not on the 6m stop is hanging on the detached transfer line. Emergancy release clip is at the top of this line.




ATB

Mark Chase

[Gareth J]

I've done team deco for a number of years now. Tagging in on descent, having to return to the shot, & decompressing on a trapezze.

It makes real sense when you have long hangs, anything over 30 minutes, or if you are in or near a busy shipping lane. Nice to have all that support & extra gas sitting on the trapezze if anything goes wrong.

I've missed the shot & trapezze three times.
Once because no one (& I mean no one) could sort the blue shot out from the hundreds of bits of blue rope floating off the wreck towards the surface. The skipper got a hell of a shock as 10 DSMB's hit the surface, apparently all within 5 minutes of each other (did he take the piss on the next outing when we put the trapezze in).

Second time was in the channel islands. Bad weather coming in, we where supposedly the last pair, & we supposed to cut the waister as we left the bottom. We returned to the shot slightly early, checked it was still in position, moved further up the wreck as one of the last pairs passed us returning to the shot, when't back 5 minutes later, no shot (still inside our planned run time). We drifted down the wreck then bagged off when we couldn't see any sign of the shot. Apparently the guys on the shot felt the whole thing give way. The skipper was less than impressed! I must admit feeling somewhat worried as we drifted along all on our tod with no surface support. Couldn't have been that bad, the skipper found us before the reel blow started - very hairy return to Dartmouth from what I remember.

Third time was kit failure, on independent twins one of the second stages failed. We tried to swim back & it became obvious that we wheren't going to make it so we bailed out, popped a DSMB & ascended, drifted onto someone elses shot decompressed a while until they pulled their shot. Then had a long swim/wait for the boat to find us. I skipped all the deep stops to get on the travel as early as possible, ascending up the other shot, when they pulled the shot out we seperated.
I must admit the look on their faces as they descend their shot to find two divers on it was a picture, less funny when they ascend past us then pulled the shot.


Generally if you aren't on the trapezze it's your own fault! Couldn't agree more.

Gareth

[Jetsam]

Originally Posted by Mark Chase

Also if you didnt notice on the previous thread. The diver lost for several hours (not dead) out of Dover returned to his primary tie in and found the shot was no longer on the wreck. The waster had failed / broken than the station loaded with divers had dragged the shot off the wreck and away.

I am aware of that incident, but it is not strictly the same scenario, there was no deco station, just the shotline, and it was the weight of the boat on the end that snapped the waster, the anchor jumped and then caught further down the wreck.

It's not a commonly encountered situation when using a deco station. The boat is usually standing off.

Nice drawing by the way

Regards

[The Purist]

The group I dive with has been using a station since we started doing 'deep' wrecks back in the late 90s. In all that time I think we've had two pairs of divers fail to come back up the line - both caused by poor navigation on the wreck.

Our deco station & procedure has evolved over the years to the point where some skippers (you reading this Mr K ) actually deploy it for us. Seriously, the most important thing is to ensure that the skipper is fully aware of the procedure and that the divers listen to any thought the skipper has about the best way to deploy from their boat etc.

We use strobes to mark the bottom of the shot, 1 per diver, but don't rely on these as a marker for who's ascended. We use a prussic loop to fix the transfer line to the main shot, with a pin release clip at each end. We also stage a cylinder of 50% on the transfer line and O2 on the 6m bar but these are belt & braces rather than integral to bailout plans.

Using a station successfully involves a team approach from everyone on the boat - but when in heavily trafficed areas such as the end of the lanes there is no way I'd want to rely on the skipper tracking a bunch of blobs & fending off the shipping from each. Unfortunately a significant amount of deeper diving seems to be done by groups of individuals who just book spaces on boats, so there's nobody to coordinate the approach needed for a station to work.

Yes there are con's to stations - they require proper navigation (but you ARE paying attention down there aren't you?), can require a bit more effort to monitor your buddy during the ascent and when TSHTF you still have to be able to bag off, but IMHO the pros still outweigh the cons - YMMV.

[Jetsam]

Since I'm not too sure that some who maybe don't use this system could be a bit baffled I'll add in a few scenarios ( and I'm bored!).


1. The perfect dive.

The shot and station are in as described in the first post and as per the drawing. The divers are deployed over about a 15 min interval. They complete their dives, and ascend, removing their own strobes from the bottom, and clips at 21m, and eventually end up on the bar. The last divers return, seeing 2 strobes (their own) they have a quick scan to see that no-one has taken their strobe off but is still nearby. This done, they cut the shotline to wreck waster that was tied on by the first pair at the beginning of the dive. They ascend to 21m and see just 2 clips (their own) they take them off, a quick check then disconnect the station. They then complete their stops and eventually join the rest on the bar. As the station drifts away, the skipper nips in and pulls his shot back. He then shadows the divers on the station until they are all up and the station is recovered aboard.

Everyone is happy


2. The not-so perfect dive.

As above, but the last pair return to the shot, and see 2 strobes still on it, they remove them and cut the waster and ascend to 21m. Here they see 3 clips!! At this point they take their 2, but must leave the station clipped on, there may be one more diver, who's strobe may have fallen off. They ascend to the station, but then it becomes obvious that some muppet forgot to remove a clip! Ok, no problem, detach at 6m and drift. The skipper can still pull the shot and all of the lower station rope comes with it, so nothing is lost.

Someone will have a red face, but no harm done


3. The complete cock up.

As above, but the last pair return to the shot and see 4 strobes still on it. They remove their own strobes, but assume 1 pair are still down and leave the waster. They ascend to 21m and see 4 clips. They take their own but leave the station tied in. They ascend to 6m. There they all have a bit of a bumpy ride until they decide the last pair are overdue and detach at 6m. The shot is still tied (well) in. The skipper may lose his weight and all the lower station ropes are lost with it A pair have got bored/lost and decided to DSMB up..... Muppets!

Assuming they do get back there will be mucho swearing and they may not be invited back. They could also get an invoice for the lost equipment if it is unlikely to be recovered.




I hope thats clearer, some groups may have variations on that theme, and I'm not saying what's best, just that system works if everyone is on the ball.

Regards

[Mark Chase]

Originally Posted by Jetsam

Since I'm not too sure that some who maybe don't use this system could be a bit baffled I'll add in a few scenarios ( and I'm bored!).


1. The perfect dive.

The shot and station are in as described in the first post and as per the drawing. The divers are deployed over about a 15 min interval. They complete their dives, and ascend, removing their own strobes from the bottom, and clips at 21m, and eventually end up on the bar. The last divers return, seeing 2 strobes (their own) they have a quick scan to see that no-one has taken their strobe off but is still nearby. This done, they cut the shotline to wreck waster that was tied on by the first pair at the beginning of the dive. They ascend to 21m and see just 2 clips (their own) they take them off, a quick check then disconnect the station. They then complete their stops and eventually join the rest on the bar. As the station drifts away, the skipper nips in and pulls his shot back. He then shadows the divers on the station until they are all up and the station is recovered aboard.

Everyone is happy


2. The not-so perfect dive.

As above, but the last pair return to the shot, and see 2 strobes still on it, they remove them and cut the waster and ascend to 21m. Here they see 3 clips!! At this point they take their 2, but must leave the station clipped on, there may be one more diver, who's strobe may have fallen off. They ascend to the station, but then it becomes obvious that some muppet forgot to remove a clip! Ok, no problem, detach at 6m and drift. The skipper can still pull the shot and all of the lower station rope comes with it, so nothing is lost.

Someone will have a red face, but no harm done


3. The complete cock up.

As above, but the last pair return to the shot and see 4 strobes still on it. They remove their own strobes, but assume 1 pair are still down and leave the waster. They ascend to 21m and see 4 clips. They take their own but leave the station tied in. They ascend to 6m. There they all have a bit of a bumpy ride until they decide the last pair are overdue and detach at 6m. The shot is still tied (well) in. The skipper may lose his weight and all the lower station ropes are lost with it A pair have got bored/lost and decided to DSMB up..... Muppets!

Assuming they do get back there will be mucho swearing and they may not be invited back. They could also get an invoice for the lost equipment if it is unlikely to be recovered.




I hope thats clearer, some groups may have variations on that theme, and I'm not saying what's best, just that system works if everyone is on the ball.

Regards

Sounds spot on to me

[warmwaterdiver]

Originally Posted by YD

You must spread some Reputation around before giving it to Jetsam again.

great post