Don't move the upline!

[TSandM]

I thought I would share an incident from yesterday's dive, where we made a mistake that caused some difficulties, but luckily, no major problems.

We were diving a wreck, and the boat had put down a grapple. In the dive briefing, we were asked to make sure the grapple was free before we came up, so that the boat could retrieve it.

We were diving as two teams. One team was a pair of fairly novice divers, and the other was three much more experienced people. The trio (of which I was a member) got in first, and descended the line. The grapple was, in fact, trapped under a horizontal beam within the wreck, and would not come loose without being moved. We did not move it on descent, as the boat was tied to it at that point. The captain had told us that, after about 15 minutes, he would put a float on the line and move the boat, and at that point, we would be free to move the grapple safely.

We started our dive. The other team came down behind us, and we never saw them (which kind of surprised me -- it's not that big a wreck). After about 20 minutes of bottom time, we had done a circuit of the bow end of the boat, and came back to the grapple. My husband signaled, and went down and freed it up, and took it to the sand at the side of the wreck. He moved it about twenty feet or so, but far enough that it wasn't visible from the point where it had been, even if you knew where to look for it.

I wasn't very happy with us doing this at the point where we did, because we had never seen the other team. I didn't know if they'd even made it down, and if they had, we had now moved the upline to somewhere they wouldn't know where to look for it. In fact, they were unable to find it, found another line (from a grapple or anchor somebody had had to cut loose) and tried to ascend on that, only to find it ended partway to the surface. So our actions caused our less experienced team to have to do a blue water ascent, which they luckily carried out without incident.

The problem, of course, was that if anybody was going to try to move the grapple, it was going to have to be our team, because we were going to be able to cope with the buoyancy changes and any entanglement issues that came from trying to do this. (And we had enough gas, in doubles, to deal with the exertion of moving what turned out to be a very heavy object!) We hadn't arranged any way for the other team to let us know they were down or had ended their dive, nor any way for us to let THEM know where we had moved the line.

In retrospect, we should have talked about all of this on the surface. It would have been quite possible for the other team to have clipped off something (Dan was carrying a safety sausage, for example) to let us know they were down, and when they left, and we could have delayed moving the grapple until they were gone. Or, if we moved it earlier, we could have run line (we were all carrying spools) from the original site to the new one. We could have pulled out the spool before we ended our dive.

Anyway, I wanted to put this up because it's actually a pretty big mistake, which could have had much worse consequences than it did.

 

[Cacia]

Curious, what was the viz?

Also, what was the depth and current? When the grapple goes down, does it risk damaging the wreck? (what is used if there are possibly divers on the wreck?)
Did someone surface and then use wet notes? What would you say the aprox weight of the grapple? Did the twosome hear the engines start at any point?

(Is there a reason you all do not have subsurface bouys permanently attached to the wreck?)

Sometimes we trade spots with a boat that shows up with divers that need to descend and it always causes a little confusion. I mostly worry about boat traffic, but like you said, the proactive and inovative use of a SMB can solve an assortment of issues, allowing the boat crew to position the diver group.

 

[TSandM]

Viz was probably about twenty feet. You could probably have seen a diver at greater distances, but a thin line or a dark grapple on the grey bottom, no. Depth was about 65 - 70 feet. There was very strong surface current on descent (I had to pull myself down on the line) but one of the lucky things about this whole story is that it had all but died by the time we ended the dive. Thus the free ascending team didn't drift very far from the boat.

I suppose the grapple has the possibility of damaging the wreck. It could certainly knock off a couple of anemones, or maybe bang off a piece of rusted metal. But I think the major damage would be done by trying to pull it up when it's caught. I don't know why we don't have a buoy on that wreck, except I don't know who'd install it or who'd maintain it.

I should have stopped Peter when he went to move the grapple, and used my wetnotes to tell him what I was worried about, but I didn't do that. One of the errors of the dive.

I don't know how much the grapple weighs, but it just about maxed out the lift capacity of Peter's wing to carry it.

I have no idea if the other two heard the boat's engines start, or even why it would matter. We all knew the boat was going to move off the line, and since it wasn't anchored, it would have to use the engines to stay positioned above us. It's a jet boat, so props aren't an issue.

 

[Cacia]

I don't know how much the grapple weighs, but it just about maxed out the lift capacity of Peter's wing to carry it.

yes, I agree that is dangerous. What would the alternatives be?
I just asked about the engines because it usually means "something is up" and we would gather in the vicinity, somewhat akin to if you hear the rapping signal. Of course current and viz complicate that.

Funny thing about those mooring situations, is you feel the need to solve it or you would just sit there.

I guess you wanted to locate the other divers and then attack the problem? I think that is what I would want to do.

 

[do it easy]

yes, I agree that is dangerous. What would the alternatives be?

The times that I have freed the grapple, I attached a liftbag to float it and make it easier for the guy on the boat to pull it up. I usaully attached the bag after setting the grapple and add just a fart of air to make the bag stand proud. That way it's already rigged for the assscent. Of course if the liftbag would complicate the tie in and removal, then it's probably not a good idea.

 

[Rainer]

Yup, just talk about it on the surface. Once in the water, I would have tied of a line to the new location and only pulled the spool upon ascent. And why even bother moving it until ascent?

 

[Walter]

How deep was it? Would it have been possible to make another dive to release the down line?

 

[TSandM]

The grapple was set in about 65 or 70 feet of water. Since it was our second fairly long and fairly deep dive of the day, I wouldn't have been thrilled about bouncing to free the grapple.

We SHOULDN'T have moved it until ascent. But even when WE decided to end the dive, we had no way of knowing if the other team had already gone up. It was likely, because they were on single tanks and use gas faster than we do, but we also didn't know if they'd had a delay in getting in the water, or something that might leave them there longer than we stayed.

This really reminds me of some of the stuff I've read about caves. We needed a marker to tell us the other team was down and hadn't left yet. It would have been trivial to arrange, had we thought about it ahead of time.

Catherine, I think you guys mostly dive off boats that are anchored or tied in. In Puget Sound, almost all our diving is off live boats, so hearing the engines running is quite normal and signifies nothing.

 

[Ber Rabbit]

Diving where they hook the wrecks can definitely be a learning experience. I learned the hard way to carry a strobe and put it on the line, we tried a cyalume stick and it didn't show up very well in 2-4 foot visibility. Those blue (or green in our case) water ascents can really raise your heart rate, my DM and I couldn't find the line even though we knew it was next to the door on the starboard side of the tug. How the new AOW students found the stupid thing I'll never know because the DM and I searched for nearly 5 minutes but I remember hanging in the middle of nowhere at 15 feet for 3 minutes HOPING we would be somewhere near the boat when we surfaced.

The second wreck was when we tied the cyalume stick to the line to make it more visible. I missed that line too, I felt my student tug on my fin and turned to see what he wanted. He pointed 2 feet above me, I was swimming right under the line and couldn't see it. I had been counting standpipes (the wreck is upside down) and KNEW the line should be between the one I was looking at and the next one but I still never saw it. Having a strobe tied off probably would have made it a lot easier to locate that line.
Ber :lilbunny:

 

[Charlie99]

The times that I have freed the grapple, I attached a liftbag to float it and make it easier for the guy on the boat to pull it up. I usaully attached the bag after setting the grapple and add just a fart of air to make the bag stand proud. That way it's already rigged for the assscent. Of course if the liftbag would complicate the tie in and removal, then it's probably not a good idea.

Another advantage of a liftbag on the grapple that it dramatically improves the visibility of the grapple.

Although I haven't used them, I have heard other divers mention using breakaway links to lightly secure the grapple if it is just going to be used as an upline rather than as a mooring for the boat. A foot or two cord/twine with 30 or 40 pounds of breaking strength might do the trick. If you are afraid the grapple might snag, you just foul it on its own line a few feet above the wreck. Has anybody tried using breakaways?