"Ripping Current" definitions

[miketsp]

Many places where we dive there are strongish surface currents ( 2-3 knots) which ease off as we descend below 10m.

But once in a place called Guarapari, a place well known for current, we anchored and everybody was really surprised because there was no surface current. We threw in a line with a buoy and it just sat there with the line all bunched up. So we started the dive and went down. Really calm. Then we suddenly got within about 2m of the bottom and it was just like being in a fast moving river and we had to grab onto the rocks and just claw our way along. The really funny scene was that one of the group had problems equalising and was still about 4m off the bottom just floating there and he was looking down at us hanging on for dear life and asking "what's going on?".
So we clawed our way, hand over hand across the rocks "upstream" for about 20 minutes and then released to do the fastest drift dive I've ever done. I think we made it back in about 2 minutes.

 

[sidney]

Why would anyone WANT to hang onto a line like a flag. delayed marker up, drift, relax /

i second that.

 

[TCDiver1]

1 knot is strong

2 knots is every strong IMO.

Agreed. A true, two knot current is a lot stronger than most people realize. Very difficult to swim against in full scuba gear.

 

[Green_Manelishi]

Why would anyone WANT to hang onto a line like a flag. delayed marker up, drift, relax /

Because in some areas it is generally not considered wise to drift under a bag. Your bag will be mere flotsam/jetsam for the freighters and other boats to run over. This is especially true if you are diving in a river. The Piscataqua River is an example. I once completed a lobster-pot-recovery dive in a current estimated to be 3 knots and building. I had to hold onto the mooring chain and it was not very pleasant.

 

[redacted]

Why would anyone WANT to hang onto a line like a flag. delayed marker up, drift, relax /

When that line is the route back to the boat boarding ladder. And a comfortable drift is the route to the zodiac chase boat (or a missing diver search effort) and some more training on boat procedures.

But, all else being equal, I'd rather drift than flutter.

 

[TCDiver1]

Because in some areas it is generally not considered wise to drift under a bag. Your bag will be mere flotsam/jetsam for the freighters and other boats to run over.

Yup, like the Straits of Mackinaw in the Great Lakes. Its a major shipping lane for Great Lakes freighters. Strong current happens there quite a lot.

 

[String]

Yet more reasons why i hate the standard system abroad of anchored boats and fixed ascent/descent points

As well as shortening the dives by near 50% (you have to get back) they cause problems and unneccesary effort in currents.

Just glad its not done here

 

[daveg1]

Why would anyone WANT to hang onto a line like a flag. delayed marker up, drift, relax /

When the wreck you are on is in the middle of a shiping lane, and the only safe place to come up is under the dive boat.

 

[flw]

When the wreck you are on is in the middle of a shiping lane, and the only safe place to come up is under the dive boat.

I find it odd that whenever this argument crops up, the shipping lane thing is almost always the answer, yet it works every week for extended deco's in the English Channel, which is used every now and again by the odd freighter/ferry.
For most wrecks shallower than 60m or so, bagging off works well, all it means is that there has to be some sort of agreement as to bottom times, so that people stay reasonably close together, and everyone has to be kitted up and ready to go as soon as the tide starts slackening off.
There are tides round here abouts that are under the influence of both the N Sea and Atlantic tides, there is not a hope you will hold onto a line and ascend to an anchored boat, in Yell Sound they go up to 12 knots on springs, 5 is not uncommon.

 

[String]

We tend to dive in and around shipping wales around west wales area and bagging off works well, you hope to dive on slack, know you'll lose slack on the hang and just have to accept you wont be able to hold on or at very least its uncomfortable.

Surface cover has to be well trained and know its job on shielding and covering drifting divers but other than that, its not a problem.

The english channel is iirc one of the buisiest lanes in the world, divers use bags all the time and deeper dives, free floating deco trapezes are used without incident.

Add that to the fact anchoring in rough seas with strong currents isnt exactly the worlds greatest idea and the fact it greatly increases the boats response time in the event of a problem isnt great either.