Diving off small boats -- Questions

[TSandM]

Peter and I bought a boat in February, and because of our rather dismal spring and summer, we haven't had it out much, so we don't have a lot of experience with the different issues that can come up when diving off a small boat. (We haven't dived a lot off anybody else's small boat, either!)

Yesterday, we had a situation come up. For our second dive, we were going to do a barge that sits in rather open water. There was a definite breeze, and the surface was a little choppy -- it wasn't bad when you were in the water, but the wind was making it hard for the boat to stay in position. We tried to anchor on the wreck a couple of times, but once the anchor fouled, and the second time we were dragging it, despite adequate scope. It was decided to create a shot line and shot the wreck. The shot line had a fender at the top for a float. The three divers were dropped on the buoy and went down the line to the wreck.

On ascent, we came up the line, and surfaced at the buoy. Because of the wind, we had some surface current, and it was hard to keep station at the buoy. The boat wasn't far downwind, and my two buddies started to swim to it. I didn't, because I didn't think the captain had told me he was in position. I was right, and he wasn't, and he told the other divers to go back to the buoy, which they did. He was trying to position the boat so we could swim downwind to it, and it wouldn't be upwind and drift down onto us. We eventually muddled through everything, and we all got back on safely, but it was impressive how far we drifted from the buoy in the process.

The questions that came up are these:

If you are ascending the line, is there any point in shooting a bag? The captain of the boat was worried about a large tug and its towed ship, that appeared to be heading straight for our buoy, but I'm not sure an SMB could have been seen any further than the buoy, nor, by the time it was seen, could the tug have changed course. (The captain contacted them by radio, but by then, it was obvious they were going to miss us.)

Once the divers are on the surface, what is the best thing for them to do? Should they try to make for the boat, or stay with the buoy until the captain okays an attempt to reboard?

Who's in charge, once the divers are on the surface?

What should be discussed in the pre-dive briefing about procedures for diver retrieval, other than signal the boat you're up and wait for instructions?

Yesterday's trip was a huge learning experience on a currently steep learning curve.

 

[Sas]

Hmm, I never dive off an anchored boat, they just put down a shot line so I am fairly used to the situation you are describing. If I navigate back to the shot line, I don't launch an SMB. When the boat comes to pick me up, they always have me swim away from the buoy towards the boat. If a diver is struggling they will hold out a long pole or throw in a rope they can use to get back to the boat. There have been a few exceptions to this, one time we were on the surface for 10mins+ waiting as the boat had to go get some people who had drifted into the shipping lane, we put up an SMB as a ferry was heading right towards us in choppy water, even though we were near the buoy.

If I drift away from the buoy whilst I am on the surface, if the shot is removed during the dive (sometimes they pull it out before I start my ascent), or if I don't bother navigating back to the shot line, I always launch an SMB and the boat comes to pick me up. I leave them in charge of where they want me to go when they are getting close! With who is in charge out of the divers, well we tend to hang on to one another as soon as we come up as it can be fairly rough so never considered that someone might swim away or not, we tend to just sit there but that has never been discussed, just seems to be what happens with the people I dive with. I think I would prefer to always stay where I am, rather than swim towards the boat. Generally slack water is well over by the time I ascend so swimming doesn't get me very far, I am either drifting with the current or swimming futiley against it! - guess it depends where you dive though.

The briefing that they give is where we should aim to surface based on what kind of current will occur after the end of slack water, we are warned we might be left on the surface a while as they always pick up people closest to the shipping lane, they tell us to launch an SMB if we don't emerge near the buoy, they tell us to move clear of the buoy as the boat approaches and we are also warned that the shot may be removed during our dive so not to worry if we navigate back to it and find it gone. I find this adequate as a briefing.

 

[dumpsterDiver]

If you are always going to come up the shot line, then you probably do not need to shoot smb's. It might be nice so that the boat driver knows for sure when you are on your deco/safety stop, however.

If there is any kind of current, you will be unable to ascend a shot line with a float on it ,because it will be sucked underwater when the drag from the ascending divers affects it.
So you should be prepared for that to not be an option. In other words be prepared for a drifting deco/safety stop hanging from your smb's.

When you do this, it is nice when the boat operator comes close to you and guns the engine a few times, so that you know the boat is with you and you are not drifting away and lost.

As for the boat pick up... The divers should stay together. Ideally they would let go of the shot line float and begin drifting when they are sure the boat operator sees them. This will aid in the pick up because it is harder to manuever the boat to a fixed, non-drifting object, plus the boat can get tangled in the line so the boat operator probably doesn't want you on the line for pick up.

To pick up drifting divers with a live boat is not hard. The operator slowly approaches the GROUP and then puts the boat in neutral and glides up to them from the UPwind side. You want the boat to be blowing over onto the divers, not having them chase it down wind. Edit: The boat would normally be approaching at a 90 degree angle to the wind unless the sun is low and visibility is impaired.

A nice little accomodation for drift diving from a small boat is to attach a loop of line from the bow to the stern that just reaches the water. Make sure it can't get pulled to the prop or something silly. This allows the divers to hang onto the rope, hand up gear and wait on the side of the boat in a safe position while each diver climbs in the back of the boat. It is certainly safer then hanging behind the divers climbing a ladder.

As for who is in charge? I never thought of that. You just hang together and wait for the boat. Everyone must face the boat and be prepard to fend off the bow and to prevent from being pushed under the boat by the wind. It is best to keep one hand on the side of the boat as it slides by on the pick up, to make sure you can't get hit by the boat if a wave picks it up and sets it down near you.

Forgot a super important drift diving rule: DO NOT swim horizontally at a very shallow depth (like 5 feet). It is very easy to float up from that depth unintentionally and you could easily be ascending ahead of your bubbles, which means it is easy to get hit by the boat. Always come up under your bubbles (if no smb) and if you have extra air, it is nice to purge the reg at 5 feet for 10 seconds which sends up a huge plume of bubbles that is very visible to the boat operator and should therefore be easy to avoid unless it is very rough.


Also the smb would probably mean nothing to a tug boat captain. The boat operator must drive the boat agressively to protect divers and he needs to try to make radio contact with other traffic to warn them of his inability to move.

 

[TSandM]

it will be sucked underwater when the drag from the ascending divers affects it.

I don't understand this -- Are you talking about when you come up the line in significant current, and have to hold onto it? We weren't holding onto anything, so we weren't affecting the line or the buoy.

The idea of having a trail line has come up in our own discussions, and sounds like a very good idea.

I'm interested in the idea that it's preferable to have the boat upwind and drifting down on the divers. This is what our pilot was specifically trying to avoid. In current, it always seems that the boat tries to be downcurrent from the divers, and let them drift down on it; is it different in wind?

 

[dumpsterDiver]

Well if there is no current and you use the shot line as a visual reference only then it will not be sucked down obviously. But IF there is a current, 3 divers on aline will make a bunch of drag and can easily suck a float down and the divers will begin to sink also, even though they are holding onto the line.

You also need to understand that CURRENTS don't matter. The boat and the divers on the surface are affected the same by the current. The only differential is the wind (the divers are not really affected and the boat is affected a lot). If the divers pay attention, they will not get sucked under the boat from the wind pushing the side of the boat, especially if they keep a hand on it and hold onto a line which extends from the stern to the bow (or midship to the stern). yes?


it is much safer to have the operator slow the boat to a stop and then let the boat drift sideways 2-10 feet laterally to the divers.

It is safer to let the wind do the work than try to use the props to get very close to the divers..

 

[gcbryan]

I've been diving off a small (private) boat at Possession Point Ferry in current with a live boat which was using a trail line. This works very well. I don't think it's a good idea at all to rely on divers having to exert themselves significantly to try to make it to the boat in current. As far as who is in charge...the captain! For the most part the divers should stay together and wait for instructions from the captain. Hopefully, most of this is covered by the captain in the pre-dive brief.

It's also good if there is a line running along the side of the boat. This is also useful for an anchored boat in current so the divers can hold on and pull themselves along to the line that goes to the anchor.

 

[don Francisco]

The OP touches on another point about the dangers of diving in or near commercial shipping lanes. Please don't read this as an attack on the divers, but as a reminder that even if you do everything right there are other dangers out there.

The captain of the boat was worried about a large tug and its towed ship, that appeared to be heading straight for our buoy, but I'm not sure an SMB could have been seen any further than the buoy, nor, by the time it was seen, could the tug have changed course. (The captain contacted them by radio, but by then, it was obvious they were going to miss us.)

Question- what would you have expected from the tug if it were on a collision course?

At the range that a commercial vessel can spot divers, surface marker bouys, or alpha flags flying on small boats, they are likely to be beyond the point where they can maneuver around them. This is especially true of tugs with tows, which already have severly restricted limited maneuverability.

It isn't a matter of right of way, it a practical matter of collision avoidence. I don't know about divers per se, but lots of pleasure boaters have died from collisions, despite possibly having the right of way, in crowded waters such as Long Island Sound, and other similar inland waterways.

You have to be extra cautious diving near shipping lanes, planning not only to avoid them, but also making sure that wind and current won't drift you into them, lest you put your captain in the difficult position of deciding whether to save his boat or save his divers.

 

[gcbryan]

In keeping with the above post, my (limited) experience in these waters regarding small boats is making sure that you have redundancy if your boat dies in the water at the wrong time which would include a smaller trolling motor and backup communications equipment in case the boat's battery dies.

I have been on a small boat in the narrow passage leading out to Waterman Wall when the engine died just as fog became 100% and we then heard the horn of the ferry. Definitely, don't count on a larger ship avoiding you even if you have the right of way.

 

[Siantis]

I work on a 60' research vessel, and here is what we do most of the time: The divers should ALWAYS ascend on the down line and float, unless there was a prior agreement with the crew (or in an emergency where you would shoot your SMB). We have them sit on the buoy until the boat maneuvers into position. Depending on conditions, we normally back right up from downwind (the vessel's screws are well forward of the stern).

When in position we wave the divers to drift/swim the very short distance to the dive platform. There are also life rings and heaving lines ready to be put over.

The only issue we encounter on occasion, is that if you have to give a shot ahead on one of the engines, you can blast a diver back away from the vessel (also good if they've pissed you off ).

As for the tug and barge, I'll assume that the boat was flying a dive flag, but i realize that they can be quite small for a recreational vessel. Basically you have to be alert, monitoring radar and aggressively radioing oncoming traffic.




Edit: Probably should of put a disclaimer about backing up to divers in here somewhere. DON'T try it with an outboard, I/O, or a boat where the props could easily come into contact with the divers, or unless you have really good boat handling skills, etc etc.

 

[TSandM]

Yes, this boat has an outboard motor, so in reality, it can't maneuver when the divers are actually attempting to board.