Getting Found - Drift or Stay Put

[Guba]

I did talk to a friend who has conducted searches similar to the ones described (not lost divers, but lost craft in which people were cast adrift. His answer was pretty much provisional. In other words, it would depend on conditions.
IF currents were "normal" or light, the search pattern would start at the point of origin (last reported position). In our case, that would be the dive site. If there were no results there, then the search would escalate with the wind and current conditions determining the direction.
IF conditions were "heavy" with lots of wind and current AND it there had been a "significant" time, the search COULD be initiated close to the projected position, taking the enviornmental conditions into consideration. The danger with this is that by starting "in the middle" of the projected path, the victims could be missed and more time would be spent retracing steps.

I think that if I were the lost diver, I'd take into the consideration how much dive traffic might be at that location. If it's a popular wreck or reef, is there a chance that other charters might visit soon? If so, that would make me want to stick around if possible and attempt to attract their attention.

 

[String]

Asked elsewhere and got the response that they often use the prediction for a maximum distance travelled line and work within that.

Also general consensus is with any real current you'd get dragged under if totally anchored.

 

[NJMike]

Being new and inexperienced, I can't really add any insight. But I'd ask this question: if your SO did not come back from a dive charter, and for whatever reason...you did not determine that until 12 hours had passed from the time the boat left the dive site...

and you notified the CG immediately but had access to another boat that could depart immediately...where would YOU go to start YOUR search?

 

[MyDiveLog]

If it were possible to tie-off and stay put without significant stress due to current, waves, etc. I would. The risk of the searchers "missing me" due to looking downcurrent would be, IMHO, more than offset by the chance that:
1) The boat that lost me would be searching near to where we were diving
2) Another dive boat coming to or by that dive spot would see me
3) The idea that, even if they started out down current, they would EVENTUALLY cover the area of the dive site.
4) The larger chance that another boat would spot me ... the thinking being that simply drifting may pull me out of a boat traffic / shipping lane.

As others said, however, the local conditions would play a major factor. Also, if I knew that the prevailing current would sweep me towards an island, I might "go with the flow." Whatever happened, I'd be scared out of my wits.

 

[EvaL]

I think it depends on the situation. Several things determine how I would respond:
1. How much current is present and current direction (is it blowing the diver away from land?), is boat traffic heavier in the current direction (increased chances of being rescued)? If the current is too strong, it may be difficult to stay at a spot over prolonged period of time (even if there's something to grab a hold of) due to lethargy.
2. How good are the dive op and local authorities in SAR (search & rescue)? In the US (such as FL Keys or, say, Cozumel), I might not be too concerned if I drift away in a popular dive site/destination as there will probably be another dive boat I can signal to for help.
That said, I think it's always better to stay close to the original location (if possible) to increase your chances of being found.
In your 2nd hypothetical situation, you'll need a reel and it might be too deep to get back down to the wreck or rock and tie off the SMB at the end of a dive. I think a better alternative is to hang on to the buoy (hopefully there's one) and keep the SMB with me, so I can inflate it even if I drift away.
After a few experiences surfacing a distance away from the dive boat and having difficulty catching the attention of the boat crew, I now dive with an air horn and SMB off boats. I may even carry a dye stick (to color the water) if I'm diving far away from shore. And always inform someone on shore: who I'm diving with and what to do if they don't see me back from my dive by a certain time.
Dive safely.

 

[Green_Manelishi]

I carry a 330' reel and never dive below 130', so getting dragged under probably isn't much of a problem.


That's really the question. Would they be looking where I should be, assuming I'm drifting, or would they always check where I started, too?

Terry

With sufficient current you will be dragged under when you reach the end of your line.

 

[grassyknoll]

With sufficient current you will be dragged under when you reach the end of your line.

I have read this a few times and wonder if it's true. Not that I would ever question GMs dive knowledge but two things make me question it. I have never seen an ocean current completely submerge a bouy, be it a crab pot marker, morring bouy or other. I don't know how much lift bouyancy a standard bouy has but I would think a fully inflated BC and empty tank would be in the balpark. And the other reason I wonder is due to my experiences waterskiing, even getting towed along at 5-10 knots in a horizontal position, I would usually not be fully submerged (note, I did not say I was even close to being a GOOD waterskier).

If anyone is willing to tie off in a reasonable current and report back it would be very enlightening, any takers.....anyone?

 

[mthirsc]

An excellent question!!!

Perhaps a Coast Guard member will jump in with some input.

Perhaps the combination of the two is best.

Initially, tie off to the wreck or bottom, if possible. And then, if one finds the current is too strong to remain on the surface, go with the flow.

the K

I am in the Coast Guard and work a lot of open ocean drift cases. Mostly vessels but sometimes persons in the water. It is true that unless there is accurate information that you have the ability to remain stationary, search planners will assume you are drifting and will use software to calculate the effects of sea current, wind driven currents, and leeway on you, the "search object."

That said, if at all possible search aircraft or boats will be set through the last known position at the beginning of the search. If no one has reported you missing for a long time this may not be practical, and as time progresses the search area will travel very far from the last known position. As time progresses, the search area grows exponentially and assets are stretched thin and won't have the time to divert many miles just in case you are tied off to an underwater object.

I worked a case in Palau this year that involved two divers adrift for 36 hours before they were found. When they were first reported missing, the local dive boats covered the last known position and nearby areas, and this would happen in most cases.

In summary, tying off would give you the best chance of being found by dive boats and local mariners, but search planners will assume you're drifting. After 10 hours or so I can't imagine any benefit to holding on unless a) another boat might come dive that spot or b) the current is going to pull you further into open ocean. For example, here in Guam, there is 2000NM of nothing between here and the Phillipines, and that is where you are headed if you let go. I'd probably hold on.

 

[Cheekymonkey]

Well if you stay in place which sounds easier said then done, that will be the first place they look. Then any reputable agency will calculate currents and look at where you should be if your drifting. So I think either way... The tieing off to the bottom sounds interesting, but if you dive in places with high currents you will see the float balls underwater on occasion, and not because the line is too short, because the current is just ridiculous.

 

[String]

I have never seen an ocean current completely submerge a bouy, be it a crab pot marker, morring bouy or other.

It happens quite frequently here and those buoys have a hell of a lot more buoyancy than a divers BC.

The physics with this would be easier to explain with a diagram but there isnt one so i'll try to write it.

If you're anchored to the bottom imagine the centre of pivot at the bottom of the sea NOT the top (as in water skiing). Current is trying to force everything flat in its direction of travel. Therefore it pulls the diver on the surface across *and down* in its attempt to make the whole thing horizontal about the centre of rotation (ie the anchor point on the bottom). If the current is strong enough to overcome the buoyancy of the surface object it will get pulled down.

See it quite often here with 3kt+ currents - pot buoys in particular are prone to it.