Wall dive advice - low experience diver

[terrylowe]

I wrote it. It was inspired by an incident in Grand Cayman where a newly certed diver was supposed to under the supervision of a guide.

http://www.scubaboard.com/forums/accidents-incidents/283416-diver-death-cayman.html

Well heck Jim! I just started hanging around SB last year, so I missed this 2009 thread. Out of curiosity, dummy me, I clicked on it. I read the first 100 posts, then got sucked in. I just HAD to read the next 2000 or so posts. I wised up and just flipped through the last 2000 or so...

Anyway...interesting read!

 

[Pliny]

Whether or not there is a hard bottom under your dive, you'll still need to work out the weighting. You will still want to do a weight check, but you can get close with some math. You'll need two numbers to do the conversion you want. First the total weight of you and all your gear but not your wetsuit. Seawater has a density of about 1.025, so you need 2.5 percent more weight (ignoring the volume of the weights themselves) to account for the additional weight of the water you are displacing. Then add 3 pounds for every pound of neoprene. Add that to the weight you had in the pool.

 

[Jim Lapenta]

Well heck Jim! I just started hanging around SB last year, so I missed this 2009 thread. Out of curiosity, dummy me, I clicked on it. I read the first 100 posts, then got sucked in. I just HAD to read the next 2000 or so posts. I wised up and just flipped through the last 2000 or so...

Anyway...interesting read!

Even more so for me. I heard the account first hand, have a copy of his computer profile and the autopsy report. The OP and her husband traveled from North Carolina to take my AOW class after they realized on that trip that even though they had been diving for years they were doing essentially trust me dives. We had a great time and remain friends.

 

[vladimir]

Seawater has a density of about 1.025, so you need 2.5 percent more weight (ignoring the volume of the weights themselves) to account for the additional weight of the water you are displacing. Then add 3 pounds for every pound of neoprene. Add that to the weight you had in the pool.

Pliny is correct, but, to be totally clear: with all your equipment on, including lead, step on a scale (literally or figuratively). Take that weight, multiply it by .025, and the result is the amount of weight to add to your weight belt. If you weigh 250 pounds fully equipped, add 6.25 pounds for the transition to saltwater. If you were properly weighted for freshwater, you will be properly weighted for saltwater. Of course, a proper buoyancy check in the water is always the final determinant of proper weighting, and you should do one in a shallow area with a sandy bottom before any wall dives.

 

[ben_wilson3301]

Besides all the other things listed. Pay attention to your ears... If you have been swimming around for a while and all of the sudden need to equilize you probably haven't been watching your depth because you are going deeper. Thats why you needed to equilize again.

Some people get distracted and this helps them stay on track. A gauge is better, but your ears are another tip to use.

 

[tlehman]

Pliny is correct, but, to be totally clear: with all your equipment on, including lead, step on a scale (literally or figuratively). Take that weight, multiply it by .025, and the result is the amount of weight to add to your weight belt. If you weigh 250 pounds fully equipped, add 6.25 pounds for the transition to saltwater. If you were properly weighted for freshwater, you will be properly weighted for saltwater. Of course, a proper buoyancy check in the water is always the final determinant of proper weighting, and you should do one in a shallow area with a sandy bottom before any wall dives.

Thanks. That's all I was really looking for... a starting point. And it sounds like it is in the same range as when I dove in Puerto Rico. Now I know something to be sure to note in my log book! I weight 185 plus the gear so we're in the same range. Thanks.

 

[DevonDiver]

A responsible dive operation will counsel and assess you before taking you diving.

Some dive operations will insist that you only do dives that are within your personal capabilies. This is a responsible attitude. Other dive operations will assure you that 'you will be ok' and that the dive guide will look after you. This is less responsible. Regardless of the professionalism of the dive guide, you will be abdicating responsibility for your personal safety to another diver. This is often called a 'Trust Me' dive. They may seem fine... until something goes wrong and/or the dive guide turns out to be less than attentive.

The issue with wall dives, is that you won't have a solid bottom beneath you should you encounter buoyancy issues. In some locations, the bottom of the wall itself may be well beneath your safe dive limits (or even beyond anyone's safe dive limits).

The safety implications of buoyancy issues where there is no bottom to stop your descent are obvious. In addition to that, you may suffer from apprehension that will make the dive unenjoyable.

Be sure to voice your concerns to the dive staff. Get a realistic appraisal of the dive site and be honest with yourself about whether your skills and confidence make that specific dive within your comfort zone. If you have doubts, opt for an easier dive location.

 

[hawkenph]

Hi all,

I just did my first wall dive last wk. I was a bit nervous and I am still working on my buoyancy. So, what I did was just stayed as close to the wall as I could to where I still had some bottom under me. But, I kept looking over the edge. I still don't feel to comfortable yet with a full wall dive. But, I will keep working on it. I have a good dive buddy and we are both heavy on safety. I also, got into a habit of having my dive computer in front of me to keep an eye of my depth.
Kurt in Cebu

 

[vladimir]

In some locations, the bottom of the wall itself may be well beneath your safe dive limits (or even beyond anyone's safe dive limits).

There's no way to know, but that seems to be the case with the dive in question. From Stuart Cove's website:

What Is A Typical Dive Profile?

Once you have boarded your boat and before leaving the dock, your crew will discuss several desired dive sites. If you have suggestions on particular sites or types of dives you want to do this trip, be sure to speak up. Based on your suggestions our crew will recommend specific sites to visit during this trip.
Typically our first dive will be a deep dive following an 80 ft for 30 minutes profile. Most likely this will be to one of our sites along the Tongue Of The Ocean wall. This wall runs for 120 miles and reaches 6000 ft in depth. (No - you don't have to go that deep.) At your deepest point we will reach 80 feet, with an average depth being 50 to 70 feet.

Once everyone is back on board we will move the boat to your second site. After an appropriate surface interval our staff will brief the second dive.

Your second dive will be either one of our shallow reefs or one of our wrecks. A typical profile for this dive will be 30 to 50 feet for 50 to 60 minutes.

 

[Dantheengineer]

The "no, you dont have to go that deep." Is a joke that regularly features in the pre-dive briefing.
It's difficult to discern vocal intonation from written script. But the friendly smile and the resultant laugh from the boat is often reassuring to newer/lesser experienced/nervous divers. (Get's old after a few hundred times tho....)

Suffice to say, know your buoyancy and you'll come back. Dont and you might not. That same can be said of many dive ops and locations. Having a cert means you understand enough of the dangers to be safe. If you dont remember or aren't sure.....there is NO dishonor in a refresher course. The more it turns out you actually did remember.....the more time the instructor'll have to show you more. Increasing your understanding, familiarity and comfort in the water.
The fact that you're even asking the question sets you above the usual resort style diver we enjoy in these waters.......
Every set of nice new aqualung rental regs has a suunto depth gauge. (right next to the SPG which is also worth keeping an eye on)
They dont do check out dives....If you're qualified. You're qualified.
They do keep a fairly close eye on you during the first dive. (Believe me, there's enough of'em)
You can't actually "Fall" 6000' fast in water (unless MASSIVELY over weighted). You'll have time to do something about it. You might however exceed your depth limit for training. Just familiarize your self with the inflation/dump mechanism in the "shallows" and move easy.
Have fun.