Planning and executing dives with V Planner

[declan long]

Hi Everyone

Today i bourght v planner and i have read the infomation on the algorithm and how to use the program but i have a couple of questions and some things that i would like clarifying please.

I am not interested in people saying that it says the answers to theese questions in the info because i can not find answers to my questions. Maybe someties we just need somebody to explain something in a deffernt way even if the answer is there?

So, just some infomation about my diving, i intend to use v planner to plan my dives and i have a sw petrel with vpm/b unloced so i use this algorithm.

So, my questions:

When i plan a dive with v planner and plan the same dive on my sw petrel i get similar results as expected but when we dive obviuosly the computer will follow me and not the plan. So it is very rare that we stay at the maximum depth for the entire bottom time like v planner assumes, yes we can plan dives as multi level but this is something else, for example on a wreck we plan a dive to 55m and we spend some at 55, some at 51, and so on..... So when it comes to the ascent and we ascend at say ten m/m if i was to have my first stop on my slate at say twenty four metres and my computer was showing twenty one metres, which stop should i do? which stop would you do? so basically follow the slate or follow the computer? if i was following the comuter then what is the point in the slate? as a backup you may say? but if i have been following the computer so i have not made for example that twenty four metres stop then surely now the deco according to the slate is incorrect.

So what do you do and reasons please?

Would it be fine to follow my slate but just make sure that the computer clears from whatever i do? as stops do clear even when you are deeper.

QUESTION TWO
So when i plan some dives with v planner i notice that i get stops for seconds, i understand that this is due to ascent times etc but when i have a stop for twenty secs do i follow this or just round it to one minute or ascend through the stop?

I hear that theese seconds and one min stops are actually just a slow ascent.... can someone explain this in some detail please and what do you do,, how do you write it on your slate?
Would my sw petrel computer show theese as stops or not?

FINAL QUESTION
Any body plan witj actual bottom time on v planner not including the descent time and how? for example a dive to two hundred metres the descent may take five mins but the botto time would only be seconds, how can you plan for a one min bt for example.



I know this is a long post and i thourougly appreciate all of your help.

DECLAN LONGx

 

[ajduplessis]

Q1: I dive the slate, computer as failover. All my planning and emergency effort is based on what is on the slate. I dive my plan and stick to that, simple really.

Q2:I don't really pay attention to stops made up of seconds, if your ascent is within the 10m/min they will clear before you hit the next ceiling in any case and secondly because I dive from my slate. If I recall correctly vplanner can round-up seconds somewhere within the settings.

Q3: Here I read "bounce" diving if you refer to seconds or min or 2 BT. Therefore no information provided as this is not part of my believe system.

 

[tursiops]

#1: Dive the computer, use the slate for a backup. Otherwise, set the computer to be just a bottom timer and dive the slate. The chances the computer will fail during ascent are slim, so reverting to the slate is not a big jeopardy.
#2: Reset V-Planner to give one-minute stops.
#3: Bad example; you are not ready for a 200m dive! V-Planner lets you set your descent rate, and that is separate from the BT you set...but the "BT" still includes the descent time. Live with it, it gives you a little conservatism.

You are discovering the problems of using V-Planner (lots of deeper stops) and of using a slate and computer. If backups and redundancy are really important to you, get another Petrel, and carry that instead of a slate that is based on a square profile.

 

[boulderjohn]

Q1: I dive the slate, computer as failover. All my planning and emergency effort is based on what is on the slate. I dive my plan and stick to that, simple really.

#1: Dive the computer, use the slate for a backup. O

See? You get a choice!

Yes, some people do it one way and some do it the other way. There are good arguments for either method.

The one caution comes if you use a different brand of computer, like the Suunto HelO2 and use it as the backup to your slates. If you continue to use your Petrel as a backup and follow the slates instead, it will be no problem. The Petrel will continue to adjust, so if you run into some problem that prevents you from following the slates, you can turn to the computer and find it ready to guide you to the surface no matter what the circumstances. If you use an HelO2 as a backup and follow the slates, it may decide that you have departed too much from its plan and go into error mode, giving you no backup. If you have such a computer, it will be wiser to use it as the primary and the slates as a backup.

 

[Diver0001]

When i plan a dive with v planner and plan the same dive on my sw petrel i get similar results as expected but when we dive obviuosly the computer will follow me and not the plan. So it is very rare that we stay at the maximum depth for the entire bottom time like v planner assumes, yes we can plan dives as multi level but this is something else, for example on a wreck we plan a dive to 55m and we spend some at 55, some at 51, and so on..... So when it comes to the ascent and we ascend at say ten m/m if i was to have my first stop on my slate at say twenty four metres and my computer was showing twenty one metres, which stop should i do? which stop would you do? so basically follow the slate or follow the computer? if i was following the comuter then what is the point in the slate? as a backup you may say? but if i have been following the computer so i have not made for example that twenty four metres stop then surely now the deco according to the slate is incorrect.

Ascend using certain principles. Vplanner as a sanity check, computer as plan B.

QUESTION TWO
So when i plan some dives with v planner i notice that i get stops for seconds, i understand that this is due to ascent times etc but when i have a stop for twenty secs do i follow this or just round it to one minute or ascend through the stop?

Either roll through it or hold it depending on whether or not your clock is ahead or behind your ascent schedule. Those stops are intended to limit your *ascent* rate...........You do understand that, don't you?

FINAL QUESTION
Any body plan witj actual bottom time on v planner not including the descent time and how? for example a dive to two hundred metres the descent may take five mins but the botto time would only be seconds, how can you plan for a one min bt for example.

In my mind there are phases you need to go through as a newbie tek diver and much of it has to do with how well you understand deco theory.

read.... voraciously and intelligently. For the time being measure with the thumb and cut with the scalpel (which is what most of deco theory is). Eventually you'll start to realize that it's all much easier than you thought.

R..

 

[PfcAJ]

What deco glass did you take?

 

[eelnoraa]

hmm, should this be cover in your tech training??

 

[OMANDIVER]

see Erik Browns V Planner tutorial. google Team Blue Immersion and you will find it. its just HIS opinion but adds to your overall knowledge base

 

[MasterChief D]

FINAL QUESTION
Any body plan witj actual bottom time on v planner not including the descent time and how? for example a dive to two hundred metres the descent may take five mins but the botto time would only be seconds, how can you plan for a one min bt for example.

I think the easiest way would be to calculate the descent time, based on your descent rate, add this to the total desired bottom time and input the sum into VPM as the bottom time - don't know of any other way.

 

[Diver0001]

I hear that theese seconds and one min stops are actually just a slow ascent.... can someone explain this in some detail please and what do you do,, how do you write it on your slate?

I wanted to get back to this question.

In terms of nitox diving, your ascent can be broken up into three main stages

1) the deep/bottom part where you ascend from your maximum depth to where you start offgassing
2) the intermediate phase where you slow your ascent down after off gassing starts
3) the shallow phase where most, if not all of your required stops are done

The idea is to ascend as follows:

1) From the bottom to your off-gassing depth, you ascend @ 10m/min.
2) When you reach your off-gassing depth, you slow your ascent to 3m/min
3) When you reach your shallow depth you do required stops and slow your ascent to dead slow. Dead slow is a vague concept but @ 6m or less you should be thinking in terms of 1m/min or even slower unless there is a compelling reason to go faster..

So... connecting that to the short stops Vplanner shows you. If you look at those stops and add up the whole depth you traverse from the first stop to the first stop longer than 1 min and then divide it by the number of minutes of stops then you'll see that it's going to give you an "average" ascent rate of 3m/min.

That's the same ascent rate I said you would be looking for in part 2 of your ascent.... ergo, you can see the stops as a handy way for you as a diver to strictly control your ascent rate. When you're in the intermediate phase and you use both your clock and your depth to control these stops then each ascent you make will be spot-on 3m/min.

The next question is where you put the first of the 1 min stops. That's the offgassing depth. Keep in mind here that if you do extreme dives using multiple trimix mixes and such that this technique will probably break down, but for Nitrox or air you can use this as a rule of thumb.

Historically there have been three rules of thumb for finding your offgassing depth

1) ascend from the bottom to 80% of your maximum depth (for air diving, probably too deep)
2) ascend from the bottom 2 ata (20m) above your maximum depth (for air diving probably too shallow in some cases)
3) ascend to 1/2 of your maximum depth (for air diving probably in the ballpark)

I'll add a 4th way to this, which is the Diver0001 method. Use it at your own risk.

What I do is to use 21m for all my air and nitrox dives as the fulcum point and do the following:

1) Ascend to 21m at 10m/min and stop. Change gasses. After this, the ascent slows to 3m / min, which means 1 min stops every 3 metres.
if
a) the total bottom time when i left the bottom was 45 min or less extend this stop to 2-3 min to take advantage of the oxygen window
b) if the total bottom time was 45-55 min then insert a deep stop at 18m as well (extend the stop by 1 min)
c) if the total bottom time was over 55 min then insert the deep stop at 15m instead (extend the stop by 1 min)

breaking this down:

for air/nitrox diving 21 metres is significant because that's when you can change to 50%. It's also pretty close to what rules #2 and #3 above will give you if you're diving deep.

doing (a) (extending the stop where you change gasses) just takes advantage of the oxygen window. Once you change over to 50% your breathing gas will have less nitrogen in it than the gas you were using on the bottom so even if you wuold have been on-gassing with bottom gas, you will start to off-gas for a while after you change to your deco mix. That makes 21m an obvious spot to make an extended stop

(b) and (c) take advantage of knowing what you know about the RDP. What it does is insert a second deeper stop at the point during the ascent when all of your faster compartments are off gassing and your slower compartments still have a "time buffer" before you get to the NDL at that depth. For example, for air diving the 18m NDL is 56 min. So if you're at 18m and your bottom time was 45 min then you know that everything is off gassing except the slower compartments which will become saturated at 56min, so in theory you could extend that stop to 11 min and still be off gassing all of the compartments that were saturated on the bottom.

Hence, 18m is an obvious spot to put in a deep stop. This is also the reason why I put the deep stop at 15m if the bottom time was longer, even though it might seem somewhat counter intuitive at first glance to put in a "deep" stop at a shallower depth. The point being that if your slow compartments are getting saturated that spending too much time at 21 and 18 metres could be counter productive for your deco.

As for writing it down.... I don't. All I need to remember is this :

21 metres

That's it. Everything else is stuff that just becomes your SOP

What I do write down are the required stops, which are the stops longer than 1 min and contingencies including if you have to do deco on back gas or you have stayed 5 or 10min longer on the bottom than you were aiming for.

All of that can be put like this

depth..target....+5.......+10.....backgas
========================
9m // 4min // 6min // 8min // 15min
6m // 8min // 12min // 15min // 23min

etc etc. Those aren't real numbers I just made them up for this example of how i write it down.

My ultimate fall back and my ultimate sanity check is to follow what the computer says. I'm not one of the cool kids that thinks computers are for losers so I actually use one, but I've never done a dive where the computer wasn't clear well before I was done with ascending using the Diver0001 method.

Any of that make any sense?

R..