Running time or stop time - which do you use for deco dives?

[MikeFerrara]

I use stop times but I got in the babit on noting when I get to my first stop. That makes it easy to check my runtime for the stops if I want to.

 

[PerroneFord]

This is a VERY interesting topic. I am not a technical diver yet, but I do try to plan my dives like I am. I use runtime with V-Planner/M-PLan.


Though this might be a poor assumption I'd surmise that if you are early to your first stop (assuming it's not a gas switch), you just do the normal stop time, and when you get to the normal first or only gas switch, you make up the difference in time and get back on plan, using the oxygen window to full effect.

If you are late leaving the bottom, I'd guess it would be wise to make the normal stops and just BE late all the way through the plan, or make up the difference at the first gas switch and extend the last stop, and perhaps take extra time after the final stop getting to the surface. I could see how stop times would be VERY effective for fixing an issue if you left the bottom late. But I think running a second run-time profile with a +5minute bottom time would also be effective.

I think in both instances, you'd want to make DARN sure you had sufficient gas to finish the plan. I could see this being an issue if you were early onto the stop at the gas switch and were carrying a smaller bottle. Especialy if you or a buddy were dealing with a lost deco gas and you were SHARING that bottle.

 

[limeyx]

This is a VERY interesting topic. I am not a technical diver yet, but I do try to plan my dives like I am. I use runtime with V-Planner/M-PLan.


Though this might be a poor assumption I'd surmise that if you are early to your first stop (assuming it's not a gas switch), you just do the normal stop time, and when you get to the normal first or only gas switch, you make up the difference in time and get back on plan, using the oxygen window to full effect.

If you are late leaving the bottom, I'd guess it would be wise to make the normal stops and just BE late all the way through the plan, or make up the difference at the first gas switch and extend the last stop, and perhaps take extra time after the final stop getting to the surface. I could see how stop times would be VERY effective for fixing an issue if you left the bottom late. But I think running a second run-time profile with a +5minute bottom time would also be effective.

I think in both instances, you'd want to make DARN sure you had sufficient gas to finish the plan. I could see this being an issue if you were early onto the stop at the gas switch and were carrying a smaller bottle. Especialy if you or a buddy were dealing with a lost deco gas and you were SHARING that bottle.

What we do is:

Plan dive for given bottom time and depth. All stops are in # of minutes. For now, gas switch is always 70 feet. Deep stops are all 1 min up to 70.

Then we plan deco for +/- 5 mins and +/- 10 feet. If you can do this in your head, it's much easier than taking 4 tables.

The important number in our case is gated on the deco bottle -- single AL40. Gives a max of about 30 mins of deco.

For instance, today we planned 150 for 25 mins -- 25 mins deco.
Actually ended up doing 130 average for 30 mins. 20 mins deco.
Since we had memorized a 20 minute deco plan (which is same as 5 mins shorter bottom time at 150 feet), we just ran that one.

 

[Scared Silly]

Thanks for all the replies. Interesting, seems like a fairly even split between stops and runtimes. Though I did not mention when I do my tables I do mutliple tables for +/-5 minutes. I will have to look at being able to use a table for -5min and -10ft as currently I have not worried the depth as I watch that carefully ;-).

 

[double80s]

I write both RT and stoptime on my slate. I´ll also write the depth were off-gasing starts.

If I get to the first stop early (and don´t feel like hanging around) I´ll just follow the stoptimes and move on up.

I do memorize stoptimes before the dive.

Same

 

[limeyx]

Thanks for all the replies. Interesting, seems like a fairly even split between stops and runtimes. Though I did not mention when I do my tables I do mutliple tables for +/-5 minutes. I will have to look at being able to use a table for -5min and -10ft as currently I have not worried the depth as I watch that carefully ;-).

Yeah, but it's not a popularity contest
You need to weigh up the pros and cons of each method.

What use are runtimes if your actual dive time is different?
Say you bail out at 10 mins on a 30 min planned bottom time.
Now you stops say start from 35 mins. What use are they? You aren't going to hang at your stops an extra 20 mins just to sync your bottom timer up with your deco schedule, right?

I think you need to have a good idea of the deco you need to do in your head. Memorize your first deep stop depth, gas switch depth and stops for "min" deco (couldn't find the wreck/dive site) and a deco schedule that takes into account deco stops for the planned dive, and +/- 5 mins of deco (if you are doing dives where 30 mins is about your max deco)

 

[matt_unique]

Depends on the reason for your times to be "off". Total time is necessary as the basis for the stop times of course. At X minutes, you begin your ascent. When you reach stop 1, use your stop times. Your plans (slates) should always include multiple contigencies - planned time + 5 min for example, planned time - 5 min, lost deco gas, etc. Some people also carry contingency depth plans.

I tend to exceed my total time by a few minutes (< 5 min) but I always begin the ascent right on the money. I make a point to be at the point of ascent before the number clicks over to "ascent time". I realized I was ascending slower than what I had programmed in V-planner. With a few adjustments I was pretty much right on the money in terms of reaching the surface at the correct total time. I would never reduce my stop times unless I was following my plan - 5 min contingency.

--Matt

 

[johno1]

I've done it both ways, and although the stop time technique took a little getting used to, I prefer it now. Having stopwatch capability helps alot especially with a seconds timer. The Suunto D3 is great for this.