Downwellings

[rods]

I just finished reading an article in Scuba Diving Magazine in regards to downwellings. The article talked about two incidents involving them, one ending badly and one ending good. I was wondering... how common it is to encounter one? I must admit, as a beginning diver, the prospect of running into one of these is somewhat scary.

The other aspect that I got out of the article is the fact that our lives are put in the hands of people we hope to be competent with particular dive sites. Are there certain things to look for to avoid a place that may put you in harms way and make a good dive trip end badly?

-Rod

 

[old_mike]

August 6th, 2000: 1st dive of the day at a site called Kehe Daeng off of Kakaban Island, Indonesia, i ran into a downwelling. We got carried to 153 feet (from 105 feet) in seconds! I swam sideways to get out of it as soon as i noticed that i wasn't going up even though i was finning and inflating my BC. Apparently, upwellings and downwellings are kinda like rip currents: they don't seem to be all that wide so it should be a simple matter to swim sideways out of them. That was what i had read and that was what i encountered in practice.

A few minutes later, i ran into an upwelling (MAN WAS THAT WATER COLD!!) and ended up going from 95 to 80 feet within a few seconds (my computer didn't approve of that ascent rate!) i kept swimming (finning like a bat out of hell) sideways and was out of that problem in a few more seconds (which seemed like hours at the time). Next thing, I am at 65 feet, encounter some nice warm water but oh !#$%!@#$! its a down-welling and i end up at 78 feet. Once again, i keep finning horizontally along the edge of the wall and get out of that one within seconds.

As for dive guides? I have little use for them (my buddies and i are trained biologists so we are used to spotting the tiniest of critters) but others completely disagree. The guide on duty when we went to 153 feet was too busy flirting with a 16 year old female diver to pay us any heed.
Another dive guide nearly cost me my sense of hearing and equilibrium several years ago by physically dragging me back down when i was trying to abort my dive (major pain in the ears), so my view is particularly negative. Any others out there with similar or opposite points of view/experiences?????

 

[DVG]

You ask two very good questions.

I have hundreds of dives in the ocean and in the St. Lawrence River which often has a 5 knot current and I have never encountered a downwelling so I consider them rare. I have been warned of them in the river but never met anyone who has encountered one. However I have thought about them and prepared mentally a procedure in case I get caught in one and I suggest every diver who dives in current should do the same. Which sort of slides into your second question about dive guides. YOU must always be prepared to take care of YOU. You have to make an evaluation of the dive plan (there should be one even if you have a guide) and your underwater activities independent of the dive guide regardless of where you are. You have to take into account your comfort level with what you are being asked to do and REFUSE to do it if it is not comfortable or fun. You are diving dangerously if you are diving courageously. I hope you are as lucky as I am and have a dive buddy who agrees on this principle.

 

[rods]

Thanks for the input guys...

DVG what would your procedure be? Would you swim across the current like Mike, or (as the guy in the article I read) would you drop your weights and inflate your BCD? I'd like to have a game plan (other than panic) if I run into one.

 

[DVG]

Sorry Rods, I had a family emergency and this is the first chance I've had to answer you.

My procedure will depend on where I am. If I am near something to grab such as a wall, as in Cozumel, I will grab and work my way sideways till I am out of it. If I am not able to grab something, I was advised by a commercial diver to swim with the flow but at an upward angle and to the side. Apparently the downwellings are not that large. I will definitely be pumping up the BC to slow the decent and be prepared to dump to slow the ascent. Do not dump the weight belt since that could lead to an uncontrolled ascent. Just my .02.

 

[rods]

Thanks for your input. I really appreciate it!

Hope all is well from your emergency.

-Rod

 

[old_mike]

one additional thing: there are places in the world where downwellings are frequent if not twice-daily occurrences (with the tides). The Galapagos come to mind, that hellish little wall in Indonesia (happens twice a day i later found out: too bad it slipped the guide's mind) I would think that anywhere there's a big wall at the base of a reef there would be opportunity for downwellings on a regular basis. All i can say is keep them eyes a' open!

 

[Tekk Diver]

...well then.

 

[DocVikingo]

Here is a piece I did a while back for Undercurrent http://www.undercurrent.org/ on down and upwellings. Hope you find it informative---->

http://www.undercurrent.org/UCnow/articles/Upwellings200102.shtml

Best regards.

DocVikingo

 

[Jambi]

:scared:
Just the thought scares the heck out of me. Oh well, now I have another reason to dive more often, practice!