Blue Water Diving: Got Any Tips?

[Mike Boswell]

The Red Tide is so thick off San Diego right now that it's hard to find decent vis near shore, and the ocean is literally the color of the Mississippi River for many miles out to sea.

So...My wife and I and a photographer friend did our first blue-water dive today. We took the boat out to the "9-mile bank" about 9 miles offshore where the water depth is about 2,000 feet, found a floating kelp paddy, dropped the anchor down 90 feet and tied it to a bow cleat, and jumped in.

First we played with four big Mola Mola under the kelp for a while and then attached our 25-foot jon lines to the anchor rope and just drifted under the boat, watching the jellies drift slowly by. Some of the jellies floating by pulsed and blinked with light, like alien space ships out of a Steven Spielberg movie.

The surface water was very clear - vis was probably 40 feet - and warm at about 61.5 degrees F, but starting at about 60 feet the water turned cold and dark, full of brown pea soupish stuff. Earlier we had stopped to watch some huge Fin whales, and I supposed that this stuff was their dinner.

All was fine, except it was difficult to maintain a constant depth. I was always either floating up or down in the water column, and with few visual clues it seemed like the only way to maintain depth was to continuously be looking at one's depth gauge. This was not a good option, because the parade of fascinating creatures drifting by was just too engrossing.

Can anybody give me some pointers about blue-water diving?

 

[randini]

Never done it, but from what I recall from my ex universities dive program, BWD requires a central "safety diver" that is maintaining a constant depth, kind of like a dive master. The other "satellite divers" are connected to the safety diver via ropes with releases. While the satellite divers are out and about the safety diver's job is to pay attention to the satellite divers and is constantly checking their depths (via the ropes) and if any of the satellite divers start to descend too far (judged by the angle of the rope connecting the satellite to the safety diver) the safety gives a couple of tugs to get satellite divers attention and signals them to ascend. It requires extra gear and practice. An outline for blue water diving can be found at UCSB's website HERE. Just scroll down to blue water diving and get the sea grant manual on blue water diving and read it.

DO NOT TAKE BLUE WATER DIVING LIGHTLY! People have died doing it, even entire groups have died together.

 

[Thalassamania]

I've done a lot of Blue Water diving and I'd be glad to answer any questions.

John Henie's book (Sea Grant) is a good start.

...

DO NOT TAKE BLUE WATER DIVING LIGHTLY! People have died doing it, even entire groups have died together.

If memory serves there was a single incident, with recreationaly trained divers, where there were two on the rig, with a badly tied off downline that was heavily weighted and their tethers attached with snap clips to their weight belt (one case) and BC (another diver). The down line parted from the float and started to drag them down. One diver dropped his weightbelt making things much worse for the second diver who was unable to release the snap clip that was now being pulled very hard by about seventy total lbs. of lead. You only need a few lbs. for the down line and you should always use the tether system described in the book with the ring and spinnaker shackle.

 

[Lee Taylor]

I am an engineer/inventor with many patents. It sounds like what you need is a device that measures depth and continuously operates the inflator to maintain a set depth. I don't think it is on the market yet. It sounds worthwhile. I think we will see it in the future.

 

[Peter Guy]

Mike, why would you want to maintain a constant depth? What I found fun was going up and down watching the critters. To me, maintaining an appropriate depth range was fine -- just like on a wall where I'll go up and down within a set range.

My depth gauge is sufficient for that.

 

[Thalassamania]

Your individual tether is typically 10m long, that gives you a sphere 10m in radius around the pivot diver that you can work. Typically one will observe/photograph/collect one organism and then move onto another within that sphere. The pivot diver can change where the trapeze clips to the downline as needed.

 

[TSandM]

Mike, do you have your depth gauge on your wrist? That helps a lot.

We do a lot of practice of holding precise depth in midwater as training for staged decompression dives. What I have found is that, if I have NO visual reference (buddy, upline, or structure) and I begin to watch something in the water, I will be very likely to go where it goes, whether it ascends or descends. Because I have my gauge on my wrist, I don't get very far before the deviation gets corrected, but honestly, I would find an hour spent in entirely blue water to be extremely fatiguing.

When we did the black water dive off the Big Island, we were on tethers. Given that we were more than a mile offshore, that currents are possible there, and that the surface water wasn't very flat, I was glad of the tethers. I wasn't worried about getting excessively deep, but I was worried about getting separated from the boat.

 

[Thalassamania]

The tether system that we use provides a visual depth reference (the angle of the tether line going back to the trapeze) as well as a secure method that prevents going too deep or too shallow or getting separated from the boat. I've seen the single tether system that the folks here use and I do not care for it, it may work fine if you're out there for the experience of seeing the environment, but if you need to get some work done, I'll stick to our system.

 

[Crowley]

Without a refererence or tether the whole experience can be a little disconcerting. We do blue water dives here in the summer looking for hammerheads and the guide becomes the reference point for the other divers. Without a reference, regular monitoring of the depth gauge or computer is essential, no matter what is swimming by,

Good buoyancy control is paramount of course, and having a dive computer is, I would suggest, essential, and many models have depth alarms that can be set to beep (incessantly) when you hit a pre-defined limit.

Happy diving,

C.

 

[Herk_Man]

I am an engineer/inventor with many patents. It sounds like what you need is a device that measures depth and continuously operates the inflator to maintain a set depth. I don't think it is on the market yet. It sounds worthwhile. I think we will see it in the future.

Perhaps a more low-tech suggestion. A variation on the audio-variometer like is used in sailplanes to let the pilot know if the aircraft is ascending or descending. If you are steady then you get a very low frequency audio cue. Descents would be low frequency hums and ascents would be high frequency tones.