"Riding your Computer Up" vs. "Lite Deco"

[Basking Ridge Diver]

Off topic. @Basking Ridge Diver I have done very few anchored dives. Why the extreme bounce?

When the wind is very mellow - you put down an anchor the current and the wind can stretch out the anchor line - remember it is not straight down - it has scope like an extra 75 feet depending on the depth. So if I grab a pile of mussels that weigh over 15 or 20 lbs I don't want to inflate to compensate for this extra weight - I will kick up. If I drop the bag - I am 15 or 20 lbs positive and I don't want that - so I kick up the line and at 20 feet I stop. I can sit for 3 to 5 depending - you don't drop all of a sudden but I am not staring at my PDC to monitor. Slowly your weight is pulling on the boat and the boat creeps in on you - you sometime barely notice other time you definitely notice especially at Slack tide and barely any wind... If the current is good and the wind is strong - no issue.

 

[Basking Ridge Diver]

The Oceanic Pelagic Z+ is a Buhlmann ZHL-16 based model. Its bubble models... especially RGBM that are likely to 'penalize' for ascent rates. They predict/recognize issues attributing to bubble formation and persist

My Veo 2.0 has both PZ+ and DSAT - I dive DSAT (45/95 GF) - very liberal and no violations.

 

[Basking Ridge Diver]

Not really.

I do own a cressi leonardo whose ascent rate alarm is a bit twitchy. Ascent rate is supposed to be one of the things it tracks. Looking at the log after a dive, it has way too many warning marks, probably just from moving my arm. I'm yet to notice any penalty on subsequent dives, so if it does indeed track ascent rates, there must be a duration that makes it "significant enough". I haven't bounced on the anchor line like that myself so I've no idea if those bounces could be long enough for it to count.

Definitely does not on the Oceanic - on top of that I have had to dress back up and drop down the line to free the anchor on a commercial boat - a true bounce dive - no penalties. I know because I have dove after moving to a new location and nothing in the log or shortening of the dive occurred on that dive.

 

[scubadada]

My Veo 2.0 has both PZ+ and DSAT - I dive DSAT (45/95 GF) - very liberal and no violations.

I have about 1200 dives on DSAT, very familiar. Dived a DSAT backup most of this time. Now, have a little over 70 dives on ZH-L to gain experience with the algorithm. It's not easy to match DSAT based on depth profile. Deep requires GF hi 100, mid depth 95 and shallow around 90. The two algorithms behave differently.

 

[stuartv]

Applying mathematical parameters to this is well above my intellectual capacity... and defining a +/- risk versus the safety stop would definitely be an algorithm exercise.

I own a Shearwater... so I'd be looking at my GF99 info to see what exact effect was being modelled in real time... and if it caused me concern, I'd make a decision accordingly.

If the computer's sampling rate was around 1 sec or less, I might pay attention to that. But, I think Shearwaters sample at 10 seconds (?). So, watching the GF99 when you are bobbing in sync with the wave period probably doesn't tell you much.

 

[Ayisha]

The question for me is this - on occasion my safety stop is literally a "hang" on the anchor line if I am carrying mussels or fish. The draw back is I can have a safety stop swing of about 8 feet - generally not much more than that. I can start at 20 feet and due to the slack in the anchor line I can go up or down by several feet and then I will readjust my safety stop depth.

You can just hold onto a jon line that you've clipped to the anchor line and you won't have that bouncing.

 

[KDAD]

÷1 on the Jon Line. But then you do have to establish neutral bouyancy with the load you are carrying. It's a bit of work up near the surface but doable. Just don't drop the bounty holing you down.

You could always add in a lift bag and not have to deal with the load. Sorry if too far off topic.

 

[Storker]

You could always add in a lift bag and not have to deal with the load.

This would be my preferred solution. I'm a bit wary about heavy catch bags, no matter if the diver tries to swim them up or compensates with their BCD. People have died by not realizing they ought to drop their catch bag.

So if I have a heavy catch bag, I just attach a lift bag or dSMB to it, send it up and leave it to the boat tender to recover it. Or, if I don't have a boat tender, I locate it after surfacing, and then drag it to the boat or to the shore.

 

[Basking Ridge Diver]

You could always add in a lift bag and not have to deal with the load. Sorry if too far off topic.

I thought about the lift bag but I was thinking the catch bag is still in the water so how does that help grab it and haul it in? Other than avoid the bouncing on the anchor line.
I actually think tying the bag off to the anchor line may be a better solution and easier to pull the bag from the water and then unattach when it is up on the gunnel. We shall find out...

 

[boulderjohn]

I thought about the lift bag but I was thinking the catch bag is still in the water so how does that help grab it and haul it in? Other than avoid the bouncing on the anchor line.
I actually think tying the bag off to the anchor line may be a better solution and easier to pull the bag from the water and then unattach when it is up on the gunnel. We shall find out...

You can also inflate the SMB or lift bag just enough to keep it neutral at your stop depth.