How well do you hold stops?

[GrimSleeper]

Depends on the dive and the gas load. If I've spent the bulk of the bottom segment of the dive shallower than planned depth, it's been an easy dive and I'm running a conservative schedule, then frankly something quite a lot like the planned ascent will do me - as long as I'm within 1m/3ft, it's all good, it's really about the shape of the deco curve and doing the time. That tightens up at high ppO2 on gas switches, just because CNS exposure racks up exponentially as ppO2 increases.

For bigger dives or dives that come closer to the edges of the plan, stops get a lot tighter, but as Rob observes, nobody can hold really precise stop depths without that being pretty much all they're doing and it becomes much more of a team effort. As AJ says, you should be able to hold stops exactly, but that doesn't necessarily mean you have to - you should be able to work out exactly how important that precision is.

 

[bradells]

I'm one of those metric people ... I try to stay under a half meter, and usually succeed, until I start doing things other than keeping an eye on my depth (such as mask clearing)

BRad

 

[Ste Wart]

Just out of curiosity, what "range" do you consider acceptable for a stop depth.

Depends. -/+ 25CM in the early portion of deco. Towards the end when I'm starting to get cold from the hang and my breathing rhythm is shifting then -/+ 35cm.

The first 1/2 of the dive we descend along a sloping bottom to anywhere between 33 and 38 metres depending on the day. The swim out is usually 20-25 minutes depending on depth. The computer usually shows running out of no-deco time about where we turn the dive (few min before or after). During the swim back we'll go part way over the bottom and then make an ascent to mid water so as not to accumulate too much deco-time and then hit our stops while free swimming. This is all done with zero visual reference because our viz is limited to about 3 metres. It's also sometimes done in the dark. The tasks are split so one of us controls stop depths and uses his body and light-beam to create a visual cue for depth and the other controls navigation.

We both have pretty good buoyancy control and over time we've developed much tighter control over this manner of ascent. We deliberately don't use a DSMB for reference because it would defeat the purpose of the exercise. Deco usually clears by the 9 metre stop according to the computer but the dive plan includes about 10-12 minutes at 6m because it takes that long to swim back to the point that we re-encounter the bottom again. The last part of the dive is usually another 8-10 min--give or take--from 6 metres and up and we'll surface after 45 or 50 minutes.

We're doing this strictly as a skills exercise to practice making clean stops and navigating accurately using nothing but instruments. We've probably made 50 dives like this since we started with it and I'd say we're getting pretty good at it.

This dive plan however is a different story, it sound like you are flying the computer for the dive. What is the back-up?

 

[alewar]

I try to hold stops within a foot. In conditions like what you describe, I would be challenged to do that.

BTW, Imperial divers have an advantage, because our gauges don't change until we've gone off depth a foot. Metric divers have that pesky 0.1m gauge change, so you know immediately if you are going up or down. I love metric settings to help me polish things to a fine shine; Imperial makes me feel better about things

GUE divers should always use metric

 

[Diver0001]

This dive plan however is a different story, it sound like you are flying the computer for the dive. What is the back-up?

No flying the computer. I gave the information about what the computer said to give you a rough idea of the kind of dives these are.... namely to sketch the idea that these are by no means 'big' dives.

Our ascent and stops are not custom cut per dive. They are same for all of these dives regardless of the deco obligation. They've been specifically worked out so as to cover any bandwidth of bottom time we'll accumulate. Remember, the dive is simply an exercise in ascent and navigation and the pattern is fairly similar from one dive to the next. In fact, even if we didn't get in deco at all, which does happen some of the time, then the ascent remains the same because that's the point of the dive.

R..

 

[Centrals]

GUE divers should always use metric

Depth(m), tank size(L) and content(bar) as well?

 

[chillyinCanada]

Are you people holding your shallow stops, horizontally or vertically? TS&M I'm putting you down for horizontal. Diver0001? Centrals? Ste wart? And all the rest of you?

 

[Diver0001]

Horizontal.

 

[Ste Wart]

Horizontal

Sent from my couch using tapatalk

 

[waterpirate]

Turtled and horizontal in clear water, vortizontal in low vis and current.

I think this is a loaded question. If the point of a dive is training, then the bar should be set at zero deviation. That level of underwater dressage on training = a acceptable level of performance if it all goes south on a non training dive.
Eric