Dealing with current

[Rusty Roo]

The issue is not just the regular splashing around the reef kind of dive, the issue is what happens when the current cranks and the dive has a strong potential to turn into a cluster that you regret getting into. The less capability you have to swim in your scuba equipment, the more likely you will be to end up in one of those situations.

Average ocean currents are in the range of 2 to 3.5 knots. That's about 2 to 3.5 times faster than most divers can deal with at their absolute best. Statistically, we must restrict our diving to only the very best ocean conditions that represent about the bottom 1 sigma of the bell curve for the distribution of ocean current speeds. For an arbitrary location, about 97% of ocean conditions are not really good enough for most people to plan on conducting a dive in without external help and/or being tied to the surface in one way or another, and there is a high probability that that the conditions will deviate beyond what is expected leading to a bad dive. If you can double your effective swimming speeds, that 97% will drop to something more like 83% chance of bad or un-diveable ocean conditions. If you can handle on the order of 3 knots you can deal with the statistical average meaning you've got about a 50/50 chance of being okay in a randomly selected location. Add some planning to the situation to attempt to get good conditions and the likelihood of a bad dive can drop to a very acceptable level. At about 6 knots, you'd be okay in about 97% of all ocean conditions.

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really curious where you got your numbers from?

also

"and there is a high probability that that the conditions will deviate beyond what is expected leading to a bad dive."

scenario boat dive

i don't understand this. for example say you dive a reef where the current is dictated by the tide. you know at xxxxH the current will change direction and even if you don't know then you adapt the plan, i think being so rigid that you would rather swim against a strong current than drift and deploy an smb is so idiotic i wouldn't bother.

scenario shore dive

i'm more inclined to swim against a current on a shore dive as you can't get picked up. but i think brains will overcome brawn as being smart, hugging the reef taking a lot of little breaks rather than one long swim will be the superior tactic.

also, swimming against a 6knot current - are you mad?

 

[REVAN]

really curious where you got your numbers from?

From looking at NOAA data. I have not done an exhaustive survey of the planet's oceans (not sure if the complete data exists), but it should be somewhat representative.

also, swimming against a 6knot current - are you mad?

It was posed under a an 'If' clause looking at different speed capabilities. If you can swim at 6 knots, there is little you couldn't deal with. Open ocean currents generally don't exceed 5 knots maximum. If you could move at 6 knots, the only locations you'd likely have to be cautious of are channeled waterways where restrictions through landmass can intensify the the flow.

i'm more inclined to swim against a current on a shore dive as you can't get picked up. but i think brains will overcome brawn as being smart, hugging the reef taking a lot of little breaks rather than one long swim will be the superior tactic.

I agree, completely. Also, I'll raise your wager to include using brains to make swimming easier instead of relying on brauwn to push a dirty configuration through the water. This is what I'm doing. I'm using brains to design better swimming gear. That way, I won't need to work so hard when I do need to swim. I will still use the reef and other tactics to make it easier.
As I have said:

I like my diving to be easy, relatively inexpensive and fun.

 

[billt4sf]

Thanks everyone for the comments. Sorry it took me so long to get back to you.

I found Diving Dubai’s comments to be most on the mark for what we need. Yes, I was asking more about the Indo-type unpredictable currents than about drift diving which we have done with pleasure and without issue. We already know that typically current is less on the bottom, and to can duck in the lee of rocks or whatever to relax. We would not knowingly get into strong currents – one reason we don’t usually dive wrecks, and we are even cautious about open-sea pinnacles. But what happens when suddenly a strong current is there?!? That’s the question.

For the possible surface drifts, we carry DSMB’s (one each), whistles, mirrors, lights on all dives. Maybe we should step up to the air horns as well. Can you easily keep them from going off unexpectedly?

I found Diving Dubai’s comments most useful! I wrote down the following:

1) Think about contingencies before splashing – if a current springs up, know what the options are.

2) The adrenaline can really take over – and did so in a big way on the scary dive I linked in my OP. Your comments on doing your best to relax and pay attention to buddy, computer, and air, and also finding ways to take breather(!): try to get to the bottom, check out the terrain, use the reef hook, …

3) Often, unexpected warm water can mean down currents, unexpected cold water can mean up current. And yes, in my scary dive I had no clue when I was going up or down – it all just happened.

4) Carry Gloves in case they become necessary

5) I like the suggestion of fixing the reef hook to be able to use half the line length when necessary; to have a plan to clip it to the BC when you think you might have to use it; and to use it to grab a breather and collect your thoughts.


A few of you suggested becoming slightly negative when using a reef hook, and I appreciate that suggestion. I did see a number of my colleagues using reef hooks and ending up at a rakish angle because we didn’t know or think to become a bit negative while using them.

As to suggestions that I found not particularly helpful to us for what we need now:

a) Don’t do the dive if you expect a large current, and if you find one, go up. Dudes, the issue is that sometimes you get currents which are NOT expected. As I said above, we do not typically dive in anything but a weak current. In the “scary dive” that I posted in Lessons Learned, NO ONE expected a strong current. We timed the dive with respect to tides and the moon to expect a mild to medium current. At first, it was. Only after maybe 20 mins did the sh*t hit the fan. Some people DID try to simply thumb the dive once they felt the current: they were also caught in the current and had as bad a time as I did! As did the DMs.

b) Once they hit the down current, some divers DID inflate their BCs. None said it did them a bit of good. All were carried to between 50 and 100’.

c) I have heard to try to swim perpendicular to a current, but I got to tell you: that would have been damn hard to pull off. I suspect that even the strongest swimmer might have only been able to go a few meters? Hard to imagine having the skill and strength of mind to make that happen while you’re being shot up and then down multiple times.

d) As to swimming against current: we can’t. We don’t. Unless it’s really, really small.

e) We are pretty set with our gear. We had some GREAT instruction for Fundies and we’re sticking with that. We're not going to change our fins.

Thanks all!

- Bill & Emily

 

[diver0008]

I suppose on a boat dive, if worse comes to worse, you can always deploy your SMB and ascend.

I have experienced many dives with very strong currents shore diving on Bonaire, as I tend to enjoy venturing into rarely visited waters.

Often a serious surge, and crashing waves in shallow water can make getting out and back challenging, particularly if there is a cross-current as well. I have found that once you get into deeper water, the problems subside, and as many have said here, swim into any current initially.

I have had to abort entries, once last year at the White Hole. My buddy made it out, but I could not make any headway, or even get a chance to put on the fins. I was getting pummelled. I headed back to shore and caught my breath. I was successful on the second attempt.

Recently I encountered very violent entry and exit conditions at a few remote sites on Bonaire. While keeping my eye constantly on my compass, and staying horizontal and timing my forward thrustings, I always managed to make it out. It can take a while. When I do, I relax for a few moments, check my air, and how I feel, and then determine how long I will stay out and my direction and profile. I must say that I am an expert swimmer, and quite fit. I would not attempt the dives that I do otherwise. I do use my arms when fighting my way out and back.

I really enjoy beating the challenging entries, but it is often a very physical endeavour that requires accomplished swiming techniqe, and great attention to your compass and SPG.

 

[Diving Dubai]

@billt4sf Thanks for your kind remarks, and I'm glad you found my posts useful.

To answer you question about airhorn (such as the Dive alert - I use a different brand but the principle is the same) They are fitted on your LP inflator line and require a positive button press to operate so they don't go off accidentally.

I'm now a convert to the stainless steel pointing stick. mine has a wrist lanyard. I find you can just place it on something firm and easily halt yourself or stabilise yourself where you may not get a reef hook in, or before you have time.

One downside with reef hooks is that sometimes its hard to find something firm enough to hold you. Nothing worse than it letting go.

With your DSMB I hope you have a decent length of line. If there is a current and you deploy it the DSMB will go further horizontally than it will vertically. You don't want the line to go taught and pull you off the reef. I have an Apex Spool They are really compact but have a lot of line - I use the 45m one and recently even though I only deployed it from 6m depth the surface current pulled off almost 50% of the line

Being negative with a reef hook. That's a hard one. If your anxiety goes up your diaphragm drops increasing your lung capacity thus your buoyancy. So yes dumping air is good in the short term but you will need to inflate once you get relaxed. Having a short line is useful but the disadvantage is that you can get bumped around on the bottom. Where as you might find letting out some line gets you in a smoother flow. Trial and error I'm afraid and every situation is different.

One last piece of advice. Get really comfortable with your kit and be able to find your accessories by feel in a calm manner. Struggling to get something out of your pocket or un-clipped raises the anxiety etc.

But in reality what you experienced was unusual and at least you have the experience as a building block

 

[Littlerayray]

I do all of my diving so far in the st lawrence the only way to beat the current is either hug the bottom or hide behind a structure I also find pulling myself along on a dedicated line more efficient then finning in most cases go with the flow cuz you will burn through your gas real quick fighting the current if drifting enjoy the ride watch where you are going so you don't end up like a bug on a windshield when an unexpected obstruction gets in your way

 

[cneal]

A few years ago I splashed with a three other divers in Saba. By the time I had my camera handed to me I could not see the others. I went to the bottom and used my hands on the rocks to pull myself to the anchor line where we were supposed to meet. I still remember that it was at 20 feet and I just had to get to 20 feet and go into the current to find the line. I waited on the anchor doing a flag impersonation for a few minutes and then used the line to get back to the boat. Once on the surface the current was easing. But the other three divers, which included my wife, were picked by a fishing boat a couple miles away in five foot waves and well away from the island.

One of the divers has never dove again. My wife refuses to leave the boat if there is more than minimal current. I always listen to the briefing for the depth of the anchor line so I can find it in adverse conditions.

The rest of the divers from the boat got into the water a minute earlier and were able to get deep and avoid the burst of high current. The lesson here is that conditions can change quickly and you have to be ready to deal with it.

 

[dmaziuk]

Neutral Buoyancy describes a dive with a freshly minted instructor and an OW student (? or just certified diver -- I forget) and getting into a current like that at the bottom. It ends up with the student getting picked up by a boat miles away and never diving again, and the instructor resigning and giving up DMing.

A pretty enjoyable read overall, BTW.

 

[chillyinCanada]

Diving Dubai, great stuff thanks for all. I also use the pointer on a lanyard and have used it and my reef hook to claw myself forward a number of times. At one time, I lost my good pointer from Raja Ampat and replaced it with a pretty thing that soon bent. I've replaced it with another very solid Indonesian handmade pointer.

Another Raja Ampat 'unexpected' current that had us all clawing our way along, I thought I'd drop deeper and hug to the bottom as best possible. I wasn't the strongest of the divers and made very little headway, which was personally concerning until I looked up and to my right to see every other diver doing no better.

Bill, I also have a Dive Alert. It's never gone off on its own and I've had it for 15 years. I'm more amazed that it still works when the button is depressed. I've only ever used it twice to get attention but felt the item paid for itself the first time and paid me back in multiples the last time!

I've learned how to do everything by touch (except fill my smb and read my comp/gauges). Learn your gear, play practice when conditions are good. Do visualization exercises.

Definitely take any chance you get to rest your heart rate and breathing, whether that's because you're hooked in or you've found shelter.

I'd love to be able to tell you how to successfully and easily extract yourself from a down current . . .but I can't. sure hope I learn before more trouble comes that way.