Downward currents?

[S. starfish]

A couple weeks ago I was diving with a buddy from my club, one of my first times doing so outside of our organized club dives and at a location I'd never been. The site itself was great, and the person I went with was a great buddy. While down at about 55ft we hit a really strong lateral current which would have been very difficult to fight. It swept us along quite quickly which we took advantage of for a bit, then ascended about 10 to 15 ft to escape it. All went well and we finished our dive at a more shallow depth, finished up and headed home.

I'm currently AOW with 36 dives, though I did my OW 3 years ago. If they mentioned anything about currents then I've long forgotten it, as they've never been an issue at the spots we usually dive. My biggest concern (especially here in BC, where there are some tremendous vertical drop-offs) is hitting a downward current and not knowing what to do. Do these exist? If so (I'm almost positive I've read about them here before), what's the procedure to escape them calmly and safely?

I've frequently encountered downwelling currents at various sites along the lower mainland (whytecliff, ansell, furry creek, copper cove etc.). In my experience through they've never been anything but mild and the only way one could get you in trouble is if you never look at your depth gauge. Keeping an eye on anemonies, feather stars and the movement of sediment over the rock walls should give you a pretty good clue as to what's going on. They're mild enough that simply adjusting your trim so that you're finning upwards a bit is all it takes to maintain your depth. To the best of my knowledge there isn't anything around here that will take you on a whirlwind ride to 200ft.

Whytecliff can get some pretty interesting currents along the wall/cut. I've noticed that on certain occasions the current along the wall seems to run in two side by side vertical circles flowing in opposite directions. I've done dives there where I let the current take me from about 40ft down to 80, along the wall, back up to 40ish and then back to my starting point. Quite strange but lots of fun if you enjoy a leisurely paced drift dive.

 

[TSandM]

As everybody else has said, downwellings tend to occur where currents hit vertical surfaces -- I also understand they can occur where a lateral current comes to the edge of a dropoff and "waterfalls" down, but I haven't been in one of those. The downwellings I've been in haven't been very bad. It has been easy to recognize you're headed down, and kick up and inflate a bit until you are out of the current. I'm actually far more afraid of upwellings, because I've been kicked up more than 20 feet very fast on occasion. This happened to me in Indonesia, but it has happened to my husband on a San Juans dive. It's the only non-scooter-related buddy separation event I've had in over 700 dives.

 

[MauiScubaSteve]

My deepest dive to date is due to a downward current, at Molokini Crater off Maui. When you drift around the East tip at 120', where the sharks hang out (Shark Ledges), there is often a strong down on the outer slope of the submerged cinder cone.

My assignment that day was to shadow Slippery Ron who I was warned would not be paying attention to anything but shooting pictures of the grey reef sharks most likely to be below us. Even though everything went exactly as expected I was at 148' when I got ahold of his ankle to drag him up. His gauge showed 155' max. We returned quickly to 80' to begin a leisurely multilevel drift and still made a 30+ minute dive that my Suunto didn't complain about. The Captain and bosses told me I didn't do too bad???

In that situation, swimming straight up produces a perpendicular to current trajectory.

 

[MXGratefulDiver]

As everybody else has said, downwellings tend to occur where currents hit vertical surfaces -- I also understand they can occur where a lateral current comes to the edge of a dropoff and "waterfalls" down, but I haven't been in one of those. The downwellings I've been in haven't been very bad. It has been easy to recognize you're headed down, and kick up and inflate a bit until you are out of the current. I'm actually far more afraid of upwellings, because I've been kicked up more than 20 feet very fast on occasion. This happened to me in Indonesia, but it has happened to my husband on a San Juans dive. It's the only non-scooter-related buddy separation event I've had in over 700 dives.

One of your favorite dive sites ... Waterman's Wall ... is known for downcurrents. Scott and Casey found one last month when we dived there ...

... Bob (Grateful Diver)

 

[paddyp]

http://www.scubaboard.com/forums/accidents-incidents/223686-my-scariest-dive-so-far.html