Dealing with Downcurrents

[Dave Dillehay]

Reply to JAX...sorry we have not answered your question but I was waiting for someone with good info. However, I'll give you my guess ( and that is all it is). Given that downcurrents are an issue with steep walls and big coral heads making for channeling of those downcurrents, I don't think it will be much of an issue on the mainland.

One of our former DMs owns a shop in Playa and he might be able to give you better info. He is Manuel Acuna at Diving Playa del Carmen Dive Shop Mexico Dive Center provides ocean and cavern cenote scuba diving trips, padi courses in Riviera Maya.

Dave Dillehay
Aldora Divers

 

[DandyDon]

All life guards will tell you to not fight the current, but to swim parallel to the beach and you will soon be out of the current, and can probably let a wave push you back in. It is those who continue to fight the current who get into trouble.

Yeah, that's like trying to swim upstream in a fast river. We ain't salmon. Swim across the stream to get out.

The best bet is to do as your beach lifeguard told you. That is, to swim quickly across the reef and you will probably be out of it in 20 to 50 feet. They also may be difficult to detect but if you think you are swimming horizontally and all of a sudden you have to clear your ears, look at your depth gage and the reef rising above you!

Across the reef? You mean across the face of the wall?

We try to address this issue on every dive briefing, but especially at this time of year.

Good for y'all. I've never heard them discussed there; just here on SB.

I have been going to Coz for 10 years and these 2 threads are the first I have ever heard about downcurrents. How can that be?

How about that? I've brought them up at times here on SB but kinda hated being the only one usually so kinda dropped that warning. I don't see Coz as a beginner diver location as much as many seem to really. It can be okay for beginners but only with additional discussions, questions, and planning.

The thought of being suddenly sucked downward 30+ feet has me re-thinking nitrox...that bother anyone else?

A consideration yes. Unlike NC and Florida Keys wrecks and many other places where Nx is great, I am more likely to use Nx on the second or third dive of a day only for Coz.

I'd never heard of them either until I read numerous threads in the Accidents and Incidents section of this forum over a lengthy period of time. It's interesting all the things you can learn there that aren't taught by reputable diving agencies. One simple sentence about swimming parallel and up could save lives.

I had this very realization earlier today, and decided that the risk of nitrox is far too great to ever consider. Perhaps under different dive conditions like quarries it would be ok, but in areas with the potential for strong currents? It's not worth the risk, imho.

I like Nx almost anywhere else but Coz, and I'll use it there some - but the prices charges by most Ops are a bit high in part because there is only one supplier and in part because they seem to mark it up even tho the labor is the same with the air tanks they get fromt he same supplier.

Generally they follow the curve of the wall, just like a waterfall. If you move away from the wall horizontally you should swim out of it. You might be able to move side to side along the wall as well, but it could be hard to determine how wide the "fall" is.

I'd hope anyone doing this type of diving would be comfortable enough to do a blue water ascent away from the wall if necessary.

Yeah, I had a difference over this here on this forum with an expert diver/Inst/Op who said to climb the wall while I preferred to get away, but I was outclassed even tho I felt right. Just get away and do an ascent watching your depth gauge and computer to avoid fast ascents.

If stuck in a nasty down welling getting away from the wall is better??? How?
Please explain.
Thanks

Climbing wall without gloves can hurtcha! Besides, with the waterfall going over you, you have to deal with it sometime. There are also risks of getting your reg pulled out or you mask pulled off. Just get out of the stream...!

Umm . .. If I may ping y'all again . . . are these also an issue in the Playa Del Carmen waters?

I get a chuckle out of PDC questions on the Coz fourm. I always ask them on the main Mexico forum but then maybe I miss a lot of answers from Coz fans who go over there, but don't follow the main forum.

I've only dived PDC a few times. Once we crossed to dive with a turtle gathering, dozens of them getting ready to make whoopee I suppose - and the current was swift, but no walls. Another day we did 3 dives but no walls. As PDC diving is not known for walls like Coz, even if you have currents - I don't think you'll see down currents. Still, if you discover yourself in one, get out of it.

A word of warning about strong currents and your regulator exhaust flap - if you find yourself holding on to something for dear life like a reef or any other object and the water flow is rushing by you, do not turn your head perpendicular to the flow to allow the water to pass through your exhaust port. It could turn back the rubber flap and your next breath would be water instead of air. Had this happen to me in a ripping current as I was holding on to a wreck line.

 

[Jax]

Thanks, Dave, Don; It's a wee bit difficult to ascertain the underwater topography, even on Google Earth.

 

[Cave Diver]

The thought of being suddenly sucked downward 30+ feet has me re-thinking nitrox...that bother anyone else?

No. One thing I always find interesting is how people used to routinely dive deep on air well beyond a 1.6 PO2 without experiencing effects of Oxtox, but everyone seems to make the assumption that Nitrox will bring about an instantaneous hit if you cross that threshold.

Being caught in a downcurrent may seem like an eternity at the time, but odds are it's just a couple of minute event. If I suddenly found myself thrown well below my target depth on a recreational dive with limited gas, I think I'd be more grateful for the decreased nitrogen loading from Nitrox than the increased chance of Oxtox. Unless you're already really pushing your PO2 limit, an extra 30'+ for 5 minutes or so is likely to be a non-event, IMO.

Your mileage and experience may vary.

 

[firstdive2005]

I agree with cavediver on the nitrox answer.

Generally when I use nitrox it is on my second and third dives at Coz. They are nearly always going to be dives at lower depths of 80fsw or less. These dives can be along some walls but these arent likely to be affected by the wellings.
I have been caught in wellings several times, the first was the baptism by fire. My next and subsiquent events where what I call fun. I used the wellings as part of my dive at that point. I have only been in one where the person diving with me that got caught may have gotten hurt but I got to him so he did not get hurt. It's simple if your close just swim to them, and grab them hard and fast when close. Flaring stops the tumble affect pretty quick. The reason I dont freak out while trying to figure which way up is that I know I'm going to get out of it soon. This is based on my first and subsequent welling events. I had been told to swim away from the wall. Thats what I did. Got in the blue and the current drifted me a bit and I swam back towards the wall.
I was at Manzanillo diving the pinnacles and the current there was unbelievable. I just loved that dive. I'm sure some divers not versed in currents would have needed a thorough cleaning of the wet suit. There are many, many dive sites that must have questions put to the locals in way of what to expect, common or not.

I am so happy this topic has been greatly discussed as it will in my opinion help put at ease a lot of divers that may get caught. As Don stated he brought it up before. I hope it comes up again to remind us. When I brought it up I searched the Coz forum for reports and did not find any recent ones. I hope people bring this topic to the diveboat regularly. It is a great way to talk safety. This is a great way for divers to connect. Talking safety. kev

ps. As far as dms discussing every point of Coz drift diving to their divers, I dont think they are able to hit every topic and I believe it is up the the divers to ask a lot of questions also. And never be shy about it. just a thought, out loud of course.

 

[DandyDon]

Riding Nx deeper than 1.6 ppo is not something I would suggest risking. I made it beyond 1.8 once in an oops, but don't want to again. Save the Nx for the second dive. I've known divers who like Nx on every Coz dive, and they don't carry a 19 cf pony of common air like I do - some even "dive it on air computers" without analyzing! I don't agree with any of that, but to each his/her own. I've seen 6 divers leave by ambulances over the years but haven't seen one die yet at least.

 

[Dave Dillehay]

Dear FishOutUvH20,

That may be a good suggestion for people on the beach "but just waiting to conserve energy" (while going down) is not an option I would ever suggest to divers. I have never been a life guard but I have been a DM in Cozumel for many years. My suggestion was to first try to horizontally swim out of the downcurrent, and the suggestion to swim to Blue Water is equally as good in a really serious situation--but to just ride it down and conserve energy may be fine for rip currents on a beach, but could be deadly on a down current. Your point about being ever vigilant and making decisions on existing conditions is well taken, but for almost every situation I have seen in Cozumel, since 1992, down currents are easily taken care of by the cross reef or blue water strategies.

Its really not a big deal to do so, just be prepared.

Dave Dillehay
Aldora Divers

PS I would not worry about using nitrox in a situation where down currents may exist. Oxygen toxicity is a time dependent effect, and there is absolutely no chance that a down current could keep a reasonable diver down for more than a few seconds, or minutes at the most.

 

[FishOutUvH2O]

Dear FishOutUvH20,

That may be a good suggestion for people on the beach "but just waiting to conserve energy" (while going down) is not an option I would ever suggest to divers.

Dear god, I hope no one else misread my post like that. The first part of my post (post #2) is to correct a common misconception for dealing with surface rip-currents at the beach, not dealing with down-currents while diving. But, most importantly, it was meant to emphasize my main point; which was that each situation may be unique and that trying to apply one hard and fast rule may not work. It's better to take the time to figure-out what your situation is and the best course of action to deal with it.

If anyone else got the impression I meant just let the down-current take you, I apologize. I certainly don't advocate that as a method for dealing with one. And if anyone read my experience dealing with a down-current in firstdive2005's thread on this subject, you'd notice it definitely wasn't a course of action I thought to be a good idea.

 

[DandyDon]

Anyone else think this would be a good thread to stick to the top of this forum...??

 

[bhalah]

Anyone else think this would be a good thread to stick to the top of this forum...??

I have not been able to come up with any significant reasons about why it would be a bad thing to do