Lessons from a dive scrubbed that didn't need to be

[TSandM]

Peter and I have been down here in the Sea of Cortez, diving off Loreto with a friend who owns a boat here. The three of us are experienced and very conservative divers, and Dennus, the boat owner, has been coming to this place and diving here for over 20 years. For the first several days of the trip, we have only been three on the boat, and we have dived very protected anchorages, because we were leaving the boat unattended.

Today, we had a boat tender, so we decided to attempt a pinnacle out between Danzante Island and the two small rocks south of it. We had reconnoitered the site a couple of days earlier, so we knew the topography. The real questions would be whether the seas would be calm, and how much current we would encounter at the site.

We motored out there and found it without difficulty. The site consists of two pinnacles -- one comes up to about 10 fsw, and the other about 30. Visibility was excellent, and we could see the rocks at the tops of both peaks. The wind was blowing toward shore, and there weren't whitecaps, but the sea surface was disturbed by the wind. Our first attempt to anchor was unsuccessful; the anchor dragged, and we pulled it up and tried again. The second time was fine.

We put out a current line, with a float on it, and it drifted slowly east. As was our practice on this boat, my gear was assembled and clipped to a gear line and thrown into the water. I was (uniquely) the first one dressed, and I jumped in the water to test the current. It was significant. I COULD make headway against it, toward the boat, but it took a lot of effort, and that was in the wind shadow of the boat. Outside of it, it was very hard. I could not get into my gear with it clipped off, because the gear line was dragging it, and I wasn't willing to unclip it. I told the guys on the boat that there was too much surface current to do this, and the decision was made to call the dive.

We then had an amusing (and stressful) half hour, trying to get the anchor free. Peter went down and cleared it, but each time Dennus would try to bring it up, it would catch on something again. Peter reported that there was NO current at depth, and the visibility was excellent.

In retrospect, here are the errors we made:

1. We did not prepare the dive as a current dive. We should, in addition to putting out the stern line, have rigged a "granny line" along the hull of the boat to the anchor chain. This would have allowed a diver to pull himself forward and use the anchor line for descent. It's standard procedure on the dives in Puget Sound where surface current can be strong.

We should have realized that gearing up in the water wasn't going to work with the wind-driven water movement we KNEW was there.

We should have had a procedure in place for the anchor diver to signal to the boat that the anchor was free. And if we had had a lift bag to hook to the anchor, we could have gotten the hook out of the rocks, and would have been spared damaging the winch.

This dive was probably quite doable, as Peter reported no current at all at depth. We just didn't set it up right.

 

[Belmont]

Good analysis of the situation, although after the fact.

Did you have a platform you could jump from or you had to do a back roll?

Donning in the water, why?

 

[TSandM]

The boat has a transom and a swim step. There is railing around the aft deck, so no back roll. It IS possible to don gear on the boat and step over the transom and giant stride off the swim step. It's just logistically easier to throw the gear in the water and don it there, which has worked very well for us on every dive but this one. I should have realized it wasn't going to work there, because the wind current was obvious.

 

[DivemasterDennis]

Thanks for sharing your experience. I learn alot from reading posts in this forum, and you comments on preparing the boat as part of the gear set up were very useful. That is especially true because I prefer to don my gear in the water when I can. As to why? It is a personal habit and very useful on a crowded boat. You just have to remember to check air and weight and all other equipment before tossing the rig into the water, and Debbie and do a final buddy check before descent.
DivemasterDennis

 

[dumpsterDiver]

The most basic proceedure for having a diver free an anchor is to have a boat operator, an anchor line tender on the bow and a diver. The diver enters the water and descends down the anchor line. When the bow tender judges that the diver is "pretty far down" (by looking at bubbles) he signals the captain to put the boat in gear and begin to run the boat upcurrent.

The anchor/bow tender then carefully pulls in anchor line, making ever effort to keep the anchor line slightly taunt and at the same time giving the captain directions as to the appropriate heading and speed to keep the boat just slightly down current of the anchor. The objective being to pull in about as much slack on the anchor line as possible and try to get the line near vertical or a little past vertical and to take the tension off the anchor. All this is going on while the diver is descending solo.

This is a big deal in deep water, in big seas, on a big boat in a heavy current, in bad visibility.

Now when the diver reaches the anchor, he grabs the anchor and since the boat operator and tender are doing their jobs, there is no longer any appreciable tension on the anchor line and the diver pulls the anchor free. Now he gives three very large amplitude tugs on the line, which the tender can feel because they are keeping the line slightly taunt. These tugs need to be large, full arm pulls so that the tender can distinguish this signal from the effects of the bow moving up and down in swell. They do NOT need to be super HARD yanks (so as to pull the tender overboard) but they need to be long pulls that are easily felt. Some people send up a floating signal device, I never did...but the value of this method would be realized when it is super hard to feel the tugs due to sea state, depth, size of anchor line etc.

When the signal is received, then the tender begins to immediately pull the anchor line up as fast as they can for a short period of time. This is intended to get the loop of chain off the bottom and the anchor off the bottom enough that it will not re-snag. The diver can also try to manipulate the anchor so it doesn't catch.

The diver should keep in contact with the anchor. Sometimes it might be possible for the diver to lift the anchor and hook a time into a link of the chain or a shackle so that the anchor can't really catch the bottom again.

Once the tender knows the anchor is free and is coming up without an issue, they should SLOWLY pull the anchor up and the diver hangs on the anchor and simply rides the anchor up. Obviously the tender needs to pull line in slowly. Depending on the depth and good judgement, the tender then signals the capt. to take the boat out of gear and allow the boat to drift backwards, so that the diver is never near the turning propellors.

That is they way I was taught anyway. There are a multitude of ways for this to get screwed up. The biggest fears are asscoiated with a heavy anchor being pulled loose and then flying down current and trapping the diver against a wreck or something and the diver being totally unable to free themselves because the anchor line is tight and they can not cut the chain.

The other easily foreseable screw up is that the tender does not pull line in and keep the anhor line taunt to feel signals. Then the diver is on the bottom, frees the anchor line and starts tugging on the rope and he just keeps pulling arm length after arm length of loops of loose anchor line around him, which could then tighten, catch and kill him, if the boat drifts back and pulls on it. So the diver needs to stop pulling and start swearing until the topside crew does their job correctly.

The whole process is pretty simple on a 20-30 ft boat, but it can be really hazardous with a 50-80 ft boat and heavy chain anchors etc...

It is hard for me to understand how or why it would be a good idea to put gear on in the water (when it is tethered to the boat) in a strong current from an anchored boat? Sounds impractical and very difficult, even in a mild current.

I would have just avoided all this trouble and pulled a float and done a drift dive..... Either you trust the boat operator or not...

 

[lsorenson]

I would have to agree with Dumpster to some degree but without being there I will keep my thoughts to myself... TS, pretty sure your diving doubles up there but may have been singles so depending on which setup may have an impact on how I would react to this situation.

For me, I always like to see a granny line used when diving in the ocean whether I need it at the moment or not. I also dislike gearing up in the ocean but I have done so myself. I would have thought once the current was found to be little to none at depth and if I could gear up minus fins on the boat, that the dive would or could have continued.

Just my thoughts but we all make our own decisions at the time. Sometimes in hindsight we may have wished a different choice but regardless to the decision made at the time, you guys made it and at the time; I probably would have agreed with it as well...

Best to all, lee

 

[lowviz]

...//... I always like to see a granny line used when diving in the ocean whether I need it at the moment or not. ...//...

So do I.

Even better, a cross between a granny line and a Carolina line. -something like a granny line that starts at 20'.

Imagine a 25# weight hanging from the stern near the entry point. A second line is secured just above the weight and this line runs to the anchor line. The second line is connected to the anchor line with some sort of sliding connection like a shackle.

Now you have a line from the boat straight down to your safety stop depth. Then you follow the second line down to the bouncing anchor line, usually at about 40'. Saves being yanked around if there is chop and current near the surface.

-a bit problemmatic on a 10 fsw pinnacle, though...

 

[TSandM]

Thank you, DD -- I think I will forward your post to the guy who owns the boat. We could all learn something about freeing anchors, I think.

I also think one of the lessons learned here was that gearing up in the water does NOT work in any kind of current. Gearing up this way was new to me; I have done any number of dives where we took gear OFF in the water, but not put it on there. I think I concluded that it's something one can do if the water is quite still, but it won't work well if the water is moving at all, and it's something I would prefer not to do if it is avoidable. Even when the water was calm, it was annoying easy to get something twisted or tangled in the gearing up process, even though I am quite facile with my gear.

We run a granny line on our boat in Puget Sound quite often -- I've never run it from a down line as described above, though. If we had taken the time to set one up on this dive, we would have been able to do the dive.

Live boating the dive would have been another option, but in this case, I think we would never have hit the pinnacle. Going DOWN the anchor line and then having the boat pull free and pick us up would have been a nice way to do things, but in this case, would not have been possible, because the anchor was stuck.

 

[dumpsterDiver]

Thanks, Live boating is never done with divers descending down the anchor line...because as you mentioned the anchor getting stuck is an issue, I've read about some people going down a shot line or something from a live boat... but I got the impression that was for really bad vis and deep water.

For a live boat.. the boat just runs you up current of the target and when you hear "dive, dive dive" everybody bails (like skydivers) and you descend. We do it in 200 ft with 4 kt currents.. (with a 0.15 mile lead +/-)..... should be easy to hit a 10 ft deep pinnacle with good vis and moderate current and the appropriate lead.

 

[TSandM]

Well, in Puget Sound, it's actually quite common for the dive boat to come in and anchor or tie to a buoy, drop divers, and then go live for diver pickup. I've never heard of or experienced a stuck anchor here, although I have had the charter operator ask us to make sure the anchor was clear of the wreck (which resulted in another of my "lessons learned" posts ).

I don't think I would want to do a "hot drop" off a small private boat, unless the person running the boat had a lot of experience doing that kind of thing. The guy who was boat tending for us on this particular day is an experienced boater and fisherman, but not accustomed to running a boat for divers.