DIR- Generic Drifting deco - when to shoot bag?

[Wibble]

I think the "black" SMB thing comes from fishermen's habit of using black bin liners as flags on their buoys. These are actually easier to see in certain conditions in higher latitudes where mist and low sun is common.

When sailing this is quite clear as it stands out from the mist, but more so when its calm.

There's a bit of a consensus that orange SMBs are "normal", yellow are not normal and are used to alert the surface should there be an urgency below. Problem is the skipper needs to know what it means; is it that you need a drop-tank thrown in? If so, bring one and mark up your bags with clear lettering.

 

[kensuf]

I like to go to the highest point of the wreck, on the lee side, and shoot the smb before leaving. The crew on the boat gets told before I jump what time to expect to see our smbs pop and what our expected run-time is so they should have no surprises. I prep the bag and reel before the dive, so it's pretty quick to deploy and shoot.

There are some great comments in this thread about the volume of gas needed shooting a bag/smb at depth vs shallow as well as what to do if you miss the target - re-read those.

 

[johnkendall]

Something to bare in mind if looking at what is done in the UK is that we have very large, but predictable tides.
So the concept is this, Drop all the divers in down the shot, slightly before slack water. Timed ideally so the end of the planned bottom time is at around the end of the slack water time.
This means if a team heads up early, they are heading up in relatively still water and not moving much relative to the wreck. Teams that then head up at the end of planned bottom time are pretty much in the same place as anyone who came up early.

Depending on the teams, and the skipper will dictate whether it's one bag per diver, or one bag per team (When ever we fill a boat with GUE teams, we will do one bag per team if agreed with the skipper in advance)

Once the skipper has seen all the bags he's expecting, then he'll pull the shot up and then follow the bags as we drift on deco.

In terms of where we send up the bag, again, it's based on discussions with the skipper, but my preference is to ascend to around 27m depth (90ft) and send the bag from there. It normally only takes a couple of minutes to get there from a 60m or so wreck, so we haven't really moved much relative to the wreck itself.

For deeper wrecks, then it is a bit location dependent, and we'll either use a deco station on a lazy shot, or we'll bag from deeper.

HTH
John