Ten Foot/3 Metre Stops in Heavy Swells?

[Reg Braithwaite]

I was headed out to dive The Tiller this morning but they called teh dive on account of 4-6 foot waves (chime in here with your stories of doing dives in waves so big that you had to avoid surfers when ascending).

Any ways, the question that crossed my mind on my forlorn drive back home was this: does heavy wave action affect the shallow stops, especially the last stop? Taking five foot swells, for example, that means that the peak is five feet above the average water level and the trough five feet below it. So a ten foot stop ought to be five feet below the trough.

That being said, is that what actually happens if you read a depth guage? Do you hang motionless five feet below the troughs of the waves and fifteen feet below the peaks? Or does your gauge (which reads pressure) report that you are bouncing from 5 to 15 feet of depth? Do you feel the waves under such circumstances?

Just wondering what people have reported when doing 10 foot stops in heavy waves.

(I ought to know the answer from experience, but the simple truth is that until recently I have been doing my stops at 5m, and since I switching over to DIR-style one minute ascents, I haven't been out in anything serious.)

 

[D_B]

The gage bounces.
... not that I know, but I would think that safety stop at 20ft would be a safer idea because of the pressure changes going on at 10feet?
(sorry, not DIR, didn't notice the forum before I posted answer)

 

[Underwater Ogre]

The gage bounces.
... not that I know, but I would think that safety stop at 20ft would be a safer idea because of the pressure changes going on at 10feet?

Agreed...better to be safe then sorry

 

[Jim Lapenta]

Make the stop at 20. Not only easier to keep track of depth but easier on the arm if on the anchor line. Best thing to do is not make contact with it unless there's a current. Then a jon line is the ticket. If no current, use the line as a visual as opposed to tactile reference.

 

[Blackwood]

As was mentioned, the gauge reflects the swells.

 

[MonkSeal]

Then a jon line is the ticket.

AFAIK jon line is not DIR.

 

[Tigerman]

Youll feel 5 foot waves quite nicely at 10 feet, especially if youre doing a shore entry/exit.
Since you mentioned surfers, if youve got waves and a shore exit you can "surf" to the shore yourself

 

[DA Aquamaster]

A Jon Line may or may not be DIR, but it is a good idea none the less in 5' swells in a current. The line will be jumping and it is very hard on the arm and potentially hazardous. I am aware of at least one fatality where the lack of a Jon Line in heavy seas was a suspected contributing factor to AGE.

Personally, I am a big fan of doing the last deco stop or safety stop at 20' in large swells and many of the boats with Carolina rigs have the line set at 20' for that reason. With regard to a Jon Line it makes sense on a long deco in open water in a current, large swells or not.

When I consider that "DIR" originated in a cave environment, the DIR forum does not tend to be my first resort for the last word on offshore diving subjects such as Jon Lines, SMB's, uplines, etc. You may want to consider posting in the general techncial forum.

 

[Rick Inman]

In current (no swells) I have used a spool quite nicely.

 

[nadwidny]

When I consider that "DIR" originated in a cave environment, the DIR forum does not tend to be my first resort for the last word on offshore diving subjects such as Jon Lines, SMB's, uplines, etc.

While it may have originated in the caves I can assure you that there are hundreds of people diving DIR in open ocean enivronments.

For the OP, if there is a heavy swell running do your final stop deeper and don't try and hold on to anything like the anchor line. If you're not trying to stay attached to anything then you will move up and down with the water. If there is a current running then you will have to consider it's speed and look to either floating deco, kick against the current or use scooters to maintain position. As a last resort we have gone to using our spool as a sort of Jon Line but we let out enough line that we aren't affected so much by the ups and downs of the anchor line.