Strong Currents, Upwelling, and Downdrafts

[ghoombahds]

I am unfamiliar with all three and would like to hear anyone's opinions on how what to watch for, when they occur, how to predict them with any accuracy, and how to deal successfully with these three potentially dangerous forces.

Thanks!

ghoombahds

 

[3-Ring Octopus]

Strong currents? Around here we usually face those associated with tides (a lot of Jetty and Inlet diving..). To solve the problem we try to dive at high slack (that is...high tide before it starts to ebb). We try very hard never to fight a current..but if you have to (mistime your dive or "overstay your welcome") we try to fight the current (wrong word..never "fight" a current.."go against" is better) on the way out...and let it carry us back in.

Upwellings and downdrafts are things I've got very little experience in dealing with. (at least severe ones..) I'll leave that to someone else! lol

Cheers,
Austin

 

[TSandM]

Where I dive, strong currents can be predicted by large tidal exchanges. I don't think that's true elsewhere.

I found in Indonesia that I could suspect up or down currents by watching the contour of the wall we were diving. If the current was blowing along the wall, and the wall made a right angle turn, the water had to go somewhere, and often went either up or down. You couldn't necessarily predict which, but you could be alert for the first signs when you felt them. I understand you can also have downcurrents when water is sweeping across a horizontal surface and "spills" over an edge.

For the magnitude of the up and down currents we experienced in Indonesia, normal buoyancy adjustments were enough -- inflating or deflating the BC, maybe with a little finning. That's not the case when they are stronger, I know.

 

[3-Ring Octopus]

We're from the same part of the world, TSandM.... (Okay..so I'm not "from" here..but I live/dive here now! )

We'll be up in your neck of the woods on the 6-8 of March..making some dives at Seacrest Park (Alki Cove 2 more than likely...maybe a day trip to Edmonds) in West Seattle.

Cheers,
Austin

 

[ArcticDiver]

Different areas react differently with tides and current changes. Some I've seen are smooth rivers of water. Some are veritable whirlpools. Some are elevators. So, the only reliable method is to get the advice of a qualified person in the area you are. Even then you might get surprised.

In your home area you will soon enough pick up the clues.

 

[MXGratefulDiver]

We're from the same part of the world, TSandM.... (Okay..so I'm not "from" here..but I live/dive here now! )

We'll be up in your neck of the woods on the 6-8 of March..making some dives at Seacrest Park (Alki Cove 2 more than likely...maybe a day trip to Edmonds) in West Seattle.

Cheers,
Austin

Post your trip in the Orca Bait forum ... if you're planning afteroon/evening dives perhaps we could hook up ... I'm always up for diving with fellow ScubaBoardians ...

... Bob (Grateful Diver)

 

[dive_lover88]

I may not be that experienced...but i have experience down currents and also strong current.

I got caught in a strong outgoing current and had been swept about half a click from the boat and half the group that was with me had to fin all the way back.

Downcurrents i have experienced that in Manado,Indonesia. We got hit and within a matter of moments i went from 15m to 28-29m. That really caught me off guard and i got entangled in my hoses and nearly got into a big mess.

What i have learnt to watch out for natural marks, like in wall diving at the point where there is a curve, that is when the current is strongest. And also not to panic when in a down current,just keep adding air and fin your way out. Stop adding air when you feel you're out the current's grip

 

[akbpilot]

One thing I learned in my limited experience is that the vertical flow direction of a current can change quickly in relation to your position in the water column. On one of my OW check-out dives in Cozumel the instructor was leading my wife and I through some 'coral canyons' (for lack of a better term). Current didn't seem particularly strong. I was in the rear, entered the canyon a couple of feet higher where the current ran over the coral rather then down the notch, got behind my bouyancy curve a bit and ended up riding across the outcropping and meeting them on the other side. The directional change and velocity in a couple of feet of depth was quite noticeable. The instructor later advised to watch the path of bubbles of the people in front of you if diving in a group as a predictor of current direction. Sounds like it would work in at least some situations.

When I learned to fly my first instructor told me to picture air flowing around obstructions, mountains, etc., like water flowing in a stream. Over the years I got pretty good at it. Now if I can just picture water flowing like air I'll have it made.

 

[Charlie99]

The directional change and velocity in a couple of feet of depth was quite noticeable. The instructor later advised to watch the path of bubbles of the people in front of you if diving in a group as a predictor of current direction. Sounds like it would work in at least some situations.

Paying attention to marine life also gives warnings in some cases. Barracuda and some types of sharks will often hang out in a spot by swimming against the current. Fish swimming pointing up or down and swimming, but staying at the same depth is a pretty good hint that something's fishy.

Learning to watch fish in surgy conditions is good training for picking up currents, as well as being useful in knowing where one can swim into shallow areas without being thrown over the top of a reef. Just like people sheltering from wind, you will see the fish use canyons and cracks.

When I learned to fly my first instructor told me to picture air flowing around obstructions, mountains, etc., like water flowing in a stream. Over the years I got pretty good at it. Now if I can just picture water flowing like air I'll have it made.

As others have noted, the most common reason for downcurrent and upcurrent is a horizontal current passing by some sort of discontinuity.

Some people (but definitely NOT me) can sense the possibility of nasty currents/downcurrent/upcurrents by looking for unusual ripples or wave patterns on the surface. Sometimes a good, knowledgeable boat captain can spot, or at least "sense", potential problems before a dive starts.

 

[ArcticDiver]

Just have to tell a pertinent war story:

Diving off a Liveaboard in the Bahamas. Bit storm system to the South; another to the North. I was diving 29% EAN. Capt drops us off for a Live Boat Dive along a wall. Seas were 3-4 ft but manageable.

Very early in the dive I was drifting along at 70' when I turned to go around a coral head. I went down so fast I had no time to do much of anything. Tried swimming away from the wall; no effect. Tried inflating my BC; no effect. Of course all the while I'm finning up; also with no effect. Just as I decide a chamber ride is preferrable to dying and I'm getting ready to drop my weights the downcurrent let me go; at 150'. The bottom there, as I recall, is in excess of a 1000'.

After stabilizing and ascending back up to a reasonable depth and then to 20' I went through the decision process on whether to continue the dive, or to abort. I decided I'd had enough and surfaced to find the boat going away from me; of course. After getting their attention I got back on board,

The boat's divers were scattered over almost a mile. An instructor who was in the trip was absolutely petrified as he had the same ride I did.

We took a break and then continued our dive schedule. VERY educational.

NOTE: No recriminations, or "you should have done this or that", or any of that nonsense. This is a story about what happened in the past for folks to read and think about and come to their own ideas about how they would handle the situation