bouyancy without reference point.

[gr8jab]

Every PDC - and bottom timer - I've used is too slow to give me any indication of depth changes before Boyle has taken the wheel. Doesnt matter if it's wrist mounted or console mounted.

There may of course exist computers or bottom timers which can tell you your depth change within seconds, but I've yet to try one which does. So I prefer to count on old-fashioned, analog indicators.

I'm curious if the latency in PDCs is inherent in the sensing device, or an intentional feature of the software. Having a PDC readout that is too sensitive and fast to respond would be as useless as an overly slow one. Imagine there was real-time highly accurate data displayed. It would not be readable, since it would always be changing. It would not represent your actual ascent or decent, but rather every little twist of your body or movement of your arm. In fact, moving the sensor laterally in the water might actually induce a temporary false reading. Imagine your ascent alarm going 'beep' every time you went from horizontal to vertical body position!

I'm not advocating for anything. I'm just wondering if PDCs have a built in latency or moving average feature to smooth out the bumps and make the readings more user friendly, or are they just slow to collect data? Maybe they reduce the sensor sampling rate to save battery.

In sailplanes we have hyper-sensitive vertical speed indicators that can peg at max up and max down within seconds. Somewhat useless if it bumpy. Many include a 'averaging feature' where the previous 20 or 30 seconds are used to indicate a trend. Combining the two with the 'seat of your pants' is very useful.

 

[Lorenzoid]

Good question, @gr8jab --one I have wondered about myself. I agree with @Storker that a computer's indication of a depth change generally lags the optimal time at which the diver should have applied compensation (e.g., by breath, etc.). Wouldn't it be great if the ascent rate indicator that many dive computers include had a finer resolution, such that it would indicate very slight upward acceleration, and to boot, also indicated downward acceleration?

 

[scrane]

Auditory alert on deviation from a set point would be a feature on a computer that I would like to

 

[Griffo]

Good question, @gr8jab --one I have wondered about myself. I agree with @Storker that a computer's indication of a depth change generally lags the optimal time at which the diver should have applied compensation (e.g., by breath, etc.). Wouldn't it be great if the ascent rate indicator that many dive computers include had a finer resolution, such that it would indicate very slight upward acceleration, and to boot, also indicated downward acceleration?

My previous Icon I actually found too sensitive. Waving my hand would often set off the ascent alarm which was annoying. But it basically had a sensitive ascent bar on the right of the screen and a slower to update numerical display. It only did ascent though, it didn't go the other way.

 

[Ayisha]

Every PDC - and bottom timer - I've used is too slow to give me any indication of depth changes before Boyle has taken the wheel. Doesnt matter if it's wrist mounted or console mounted.

There may of course exist computers or bottom timers which can tell you your depth change within seconds, but I've yet to try one which does. So I prefer to count on old-fashioned, analog indicators.

The sampling rate and the level of accuracy probably need improvement in a lot of dive computers. I see many computers that only show 1 foot increments, which can create a sudden need for correction while maintaining static position.

I love that my xDeep Black shows 0.1 increments in depth, which makes it extremely easy to maintain static depth. By the time you hit .2 or .3 off your target depth, you know a trend is happening and you can tweak it very simply to ensure you're neutral before adding multitasking.
Meanwhile, if a person doesn't realize until their computer shows that they are already a foot off the target depth, a buoyancy shift is underway and involves a bigger correction. This can lead to over-correcting as well.

 

[Kharon]

I found my Icon sampling rate to work well in Belize. Every dive was a blue water safety stop. Vis was bad enough on shallow dives so you couldn't see the bottom. Never thought of the particles.

In order to maintain a constant depth I had to continuously watch the Icon and adjust my breathing. That constant focus was uncomfortable for me. I should have shot a SMB. I would have been a lot happier.

 

[jlcnuke]

The sampling rate and the level of accuracy probably need improvement in a lot of dive computers. I see many computers that only show 1 foot increments, which can create a sudden need for correction while maintaining static position.

I love that my xDeep Black shows 0.1 increments in depth, which makes it extremely easy to maintain static depth. By the time you hit .2 or .3 off your target depth, you know a trend is happening and you can tweak it very simply to ensure you're neutral before adding multitasking.
Meanwhile, if a person doesn't realize until their computer shows that they are already a foot off the target depth, a buoyancy shift is underway and involves a bigger correction. This can lead to over-correcting as well.

I'm curious as to what diving you're doing that being 12" off the target depth is a significant problem? GUE tech pass standards for good buoyancy requires maintaining depth within 3 feet, and rec pass at 5 ft so hearing someone say they are concerned that they might go up or down 12" seems odd to me. Obviously the better buoyancy, the better but wanting/needing to see tenth of a feet increments seems a bit excessive for the diving I've done/heard of.

 

[Lorenzoid]

I'm curious as to what diving you're doing that being 12" off the target depth is a significant problem? GUE tech pass standards for good buoyancy requires maintaining depth within 3 feet, and rec pass at 5 ft so hearing someone say they are concerned that they might go up or down 12" seems odd to me. Obviously the better buoyancy, the better but wanting/needing to see tenth of a feet increments seems a bit excessive for the diving I've done/heard of.

The finer resolution helps the diver perceive motion (or acceleration, I suppose a physicist would say) away from whatever depth the diver may be trying to maintain. Applying compensation as soon as the diver perceives motion rather than after perceiving a full foot of displacement helps with the ultimate goal of staying within that 3 foot or 5 foot window.

 

[Ayisha]

I'm curious as to what diving you're doing that being 12" off the target depth is a significant problem? GUE tech pass standards for good buoyancy requires maintaining depth within 3 feet, and rec pass at 5 ft so hearing someone say they are concerned that they might go up or down 12" seems odd to me. Obviously the better buoyancy, the better but wanting/needing to see tenth of a feet increments seems a bit excessive for the diving I've done/heard of.

The finer resolution helps the diver perceive motion (or acceleration, I suppose a physicist would say) away from whatever depth the diver may be trying to maintain. Applying compensation as soon as the diver perceives motion rather than after perceiving a full foot of displacement helps with the ultimate goal of staying within that 3 foot or 5 foot window.

Yes, exactly what Lorenzoid said more eloquently than I did. I found the .1 increments phenomenally useful during GUE Fundamentals. It was the most obvious when practicing drills across from someone and I could see from my precise depth that the other person was almost a foot higher/lower than me, but their computer displayed the target depth and they thought they were right at the target depth. Invariably, they would continue another .1 or .2 and suddenly their computer registered a whole foot different and they would correct or over-correct. They soon started looking at my precise depth on my computer to verify their depth across from me.

Regarding the 3 feet and 5 feet from the target depth, remember that is in total above and below the target depth. So not 3 or 5 feet above plus below for a 6 or 10 foot variation. For example, less than 1 foot below and 2 feet above (or ex. 2 + 3 for a rec pass) are the official standards. However, the expectation is that someone hitting 3 or 5 feet (or 30° trim) will likely go beyond those parameters when task loaded, and will be unlikely to pass. They teach and expect 0 fluctuation and 0° trim. If a diver goes beyond the parameters even once at any time, they will not pass. They may get a Provisional Pass to practice more and try again within 6 months.

If divers participate in Project Baseline surveying or anything that NAS 1 is required for, precise buoyancy is required. It's also useful for not silting up an environment.

 

[Jay]

It would be great if there were was a hover mode on the computer.

Has anyone tried honing skills using a blackout mask or closing your eyes for increasing periods of time ... all under careful supervision / safety etc.