What if...? Dive Planning & Trust Me Dives

[Cave Diver]

Of course, the problem with that in this scenario is that your boat is moored and cannot follow you until everyone else is on board. They will need to keep an eye on you as you drift, and if you drift too long, it could be a problem. That is why it is something to be avoided. If you ever have to do this, you should therefore shoot the bag as soon as possible so it comes up close to the boat.

A major consideration.

 

[MXGratefulDiver]

How do you know?

I thought you'd never ask ...

A few years ago, taking my Advanced Nitrox class, we're coming up from a 150-foot dive with about 12 minutes of deco obligation. At 70 feet, I shot my big bag ... which is a semi-closed ... on a 400-foot reel. Up it goes ... then suddenly it starts going sideways ... I let a little line out. It keeps going sideways ... I let a little more line out. All of a sudden it feels like someone's pulling it sideways ... I'm thinking it got intercepted by a passing boat or something. Not wanting to lose my bag and reel, I let the rest of the line out as we proceed up. At 20 feet, I figure out what the issue is ... there's way more current in the upper layers than the lower. Down at 70 feet, it was barely moving. At 20 feet, I figure we're doing about 2 knots. Now that we're moving at the same speed as my bag, I figure I can start reeling in the line while I'm doing my 20-foot stop. Only thing is, it feels like I'm reeling in a log ... damn thing's heavy! So I quit reeling till we're on the surface. Once there, I notice my bag sitting sideways, kinda low in the water. After reeling in the rest of the line, I noticed it was about 3/4 full of water.

Moral of the story ... current at 70 feet doesn't always tell you about current on the surface ... it can be completely different.

... Bob (Grateful Diver)

 

[Cave Diver]

A few years ago, taking my Advanced Nitrox class...

Moral of the story ... current at 70 feet doesn't always tell you about current on the surface ... it can be completely different.

... Bob (Grateful Diver)

Interestingly enough, part of my scenario was taken from lessons learned during my Trimix class. We had a few of those same lessons during a hot drop in a 4-5kt current.

I learned A LOT on that dive.

 

[Bubbletrubble]

All I remember about our wreck dive briefing is that you owed every member of the crew a case of beer if you came up the wrong line . . .

I've heard similar similar briefings about coming up on the wrong boat/mooring, whatever. Often, it's just friendly ribbing, but I disagree with using this method. It puts more stress on inexperienced divers to try and get back to their boat, instead of looking at other possible options.

I've heard those same briefings. I don't like the gist of such a briefing for the reason that Cave Diver gave. I wouldn't hesitate to come up the wrong mooring line if I thought that was the best option available.

Good pre-dive briefings walk a delicate line between being informative, covering all safety procedures, making dive customers feel comfortable, and being humorous. One of the best I've ever heard was given by a DM on a Catalina Island dive boat (King Neptune). It was the perfect balance of need-to-know info and self-deprecating humor. She referred to how she was "freakishly strong" on multiple occasions. :shocked2:

 

[Saudi-Diver]

While boat diving in Scotland we quite often end up being blown off the dive site after slack water has ended. It all ways amazes me how quickly the current builds. We are usually briefed by the Dive Boat to just deploy our SMBs and ride the current so as not to exhaust ourselves. Never been left in the water so far. I have Posiedon Cyclone Regs and they have never free flowed in any current I can hold my own in yet!!

 

[flots am]

Correct and all good points. But as they say, hindsight is 20/20

It's only hindsight once. Then it's "being prepared"

I've been teased about carrying a large SMB and a wreck reel on supposedly "easy" dives, but actually missed a wreck once and got blown off another one, so I'm willing to make an "extra" three items (SMB, finger spool, big reel) part of my normal kit, even if they aren't frequently needed.

flots.

 

[rhwestfall]

Moral of the story ... current at 70 feet doesn't always tell you about current on the surface ... it can be completely different.

... Bob (Grateful Diver)

Yep, 7 years of engineering school to learn that one... (actually it was a 3rd or 4th semester topic) and it was subsequently proven with my diving in the Niagara River....

and, it can be significantly different 25' down too.....

 

[boulderjohn]

Interestingly enough, part of my scenario was taken from lessons learned during my Trimix class.

While boat diving in Scotland we quite often end up being blown off the dive site after slack water has ended. It all ways amazes me how quickly the current builds.

I've been teased about carrying a large SMB and a wreck reel on supposedly "easy" dives, but actuall missed a wreck once and got blown off another one, so I'm willing to make an "extra" three items (SMB, finger spool, big reel) part of my normal kit, even if they aren't frequently needed.

I am just putting these three together to show how these circumstances can occur on what are normally considered "recreational" dives. The Speigel Grove is dived by recreational dives every day of the year that conditions warrant it, so John's scenario is an everyday possibility for recreational divers.

Yet the training to deal with it, as the first post above suggests, does not occur until a recreational diver decides to take technical training. In another thread I suggested that it is time to blur the line between technical and recreational diving and start teaching some of these things to recreational divers. John put this thread in the new diver forum, which I agree is where it belongs, but I believe just about all of the recreational dive agencies would argue that these are technical skills that should not be part of recreational dive instruction.

 

[rhwestfall]

...but I believe just about all of the recreational dive agencies would argue that these are technical skills that should not be part of recreational dive instruction.

and so we are back again to one very "hot" issue on my mind....

 

[Cave Diver]

@Cave Diver: Are there other moorings tied into the wreck? I've never dived the Spiegel Grove.

If there were a convenient mooring line nearby, my buddy and I could try to ascend using that. Although it wouldn't bring us directly back to our boat, it would get us to the surface without getting completely blown off the wreck. Once on the surface, we could inflate our signal tubes to get the crew's attention.

As a side note that I forgot to mention earlier. While both the SG and the O have alternate moorings, but neither goes all the way to the surface the last time I dove them. They are submerged about 15-20' so as to not be a navigational hazard and the DM will go down and tie into them.