Where Is Your GF?

[scubadada]

Using my dive Excel spreadsheet for a dive to 100 ft for 25 minutes produces 6 minutes of deco at 10 ft with 75/95, 3 minutes for 85/95, and 1 minute of deco at 95/95. The difference is significant. I would stick with 75/95. If you're not doing any deco than 95/95 might be an option.

If I'm not doing any deco, it doesn't matter what my GF low is. I'm looking at my time at 10 feet. I pad my stop for 3-5 min as it is

 

[scubadada]

Hi @EFX

Your deco times for a 25 min dive to 100 feet on air did not make sense to me, so I ran them on MultiDeco and on my Shearwater Teric. Using 1 min stop times on MultiDeco, I got 0:20 at 20 ft and 5 min at 10 ft with 75/95 and 5 min at 10 ft with 95/95. With the Teric, I got 1 min at 20 ft and 6 min at 10 ft with 75/95 and 6 min at 10 ft with 95/95.

 

[EFX]

scubadada,

Thanks for posting the screen shots of MultiDeco (MD) above. My ss calculates deco times for every phase of the dive including ascents. MD does not break out the ascents. My bottom time of 25 minutes is in addition to the descent time and not part of it as it is in MD. In MD you need to set the time to 26 minutes and make sure you set the descent rate to 60 fpm and the ascent rate to 30 ft/min. I made a minor change in the ss and recalculated and got the following results: for 75/95 total deco time was 9 minutes after rounding up and 7 minutes for the 95/95. In MD it was 9 minutes for 75/95 and 9 minutes for 95/95. Another thing to keep in mind is you have to add the ascent time to the first stop as part of the overall total deco time when comparing to my ss.

For those loyal fans who are using my ss keep the above differences in mind. I'm going to post a major release soon so look for that. There are some known bugs that I'm working on so be patient.

 

[tursiops]

scubadada,

Thanks for posting the screen shots of MultiDeco (MD) above. My ss calculates deco times for every phase of the dive including ascents. MD does not break out the ascents. My bottom time of 25 minutes is in addition to the descent time and not part of it as it is in MD. In MD you need to set the time to 26 minutes and make sure you set the descent rate to 60 fpm and the ascent rate to 30 ft/min. I made a minor change in the ss and recalculated and got the following results: for 75/95 total deco time was 9 minutes after rounding up and 7 minutes for the 95/95. In MD it was 9 minutes for 75/95 and 9 minutes for 95/95. Another thing to keep in mind is you have to add the ascent time to the first stop as part of the overall total deco time when comparing to my ss.

For those loyal fans who are using my ss keep the above differences in mind. I'm going to post a major release soon so look for that. There are some known bugs that I'm working on so be patient.

It is unfortunate that you must redefine terms (like BT) that already have agreed definitions.

 

[EFX]

I'm not redefining anything. My spreadsheet was designed for a different purpose than MultiDeco so comparing the two the differences must be kept in mind. Another SB member asked me to change the ss to conform more to other dive planning software but this would defeat my primary purpose of it being an educational tool. The important fact is that after taking in the differences my ss is in very close agreement with MD.

 

[scubadada]

I'm not redefining anything. My spreadsheet was designed for a different purpose than MultiDeco so comparing the two the differences must be kept in mind. Another SB member asked me to change the ss to conform more to other dive planning software but this would defeat my primary purpose of it being an educational tool. The important fact is that after taking in the differences my ss is in very close agreement with MD.

However, it prevents you from effectively communicating with people who are using standard definitions. To use your spreadsheet, one must be aware of the caveats and take them into account to make a comparison to planning applications or dive computer planning.

 

[EFX]

I explained the differences to you so you could make a meaningful comparison. I hope that was effective enough communication. But, you have a good point and in order to preclude future issues I will explain the differences in my ss under the dive_help tab. Thank you.

 

[scubadada]

Using my dive Excel spreadsheet for a dive to 100 ft for 25 minutes produces 6 minutes of deco at 10 ft with 75/95, 3 minutes for 85/95, and 1 minute of deco at 95/95. The difference is significant. I would stick with 75/95. If you're not doing any deco than 95/95 might be an option.

scubadada,

Thanks for posting the screen shots of MultiDeco (MD) above. My ss calculates deco times for every phase of the dive including ascents. MD does not break out the ascents. My bottom time of 25 minutes is in addition to the descent time and not part of it as it is in MD. In MD you need to set the time to 26 minutes and make sure you set the descent rate to 60 fpm and the ascent rate to 30 ft/min. I made a minor change in the ss and recalculated and got the following results: for 75/95 total deco time was 9 minutes after rounding up and 7 minutes for the 95/95. In MD it was 9 minutes for 75/95 and 9 minutes for 95/95. Another thing to keep in mind is you have to add the ascent time to the first stop as part of the overall total deco time when comparing to my ss.

For those loyal fans who are using my ss keep the above differences in mind. I'm going to post a major release soon so look for that. There are some known bugs that I'm working on so be patient.

Sorry, for those of us who are not familiar with your spreadsheet, we would not know that your bottom time does not include the descent time. We would not know that your deco time includes the entire ascent. Out of interest, for your no stop dives, do you call your ascent time, your deco time, as in every dive is a deco dive? What about the safety stop?

 

[EFX]

Attached is a screen shot of the spreadsheet (ss) showing two profiles. The first is an NDL dive to 60 feet for 45 minutes. The second is a deco dive to 100 ft for 20 minutes. Both are air, no second or deco gases, GF: 65/90, starting at sea level in salt water using imperial units.

Even in MultiDeco the deco time must include the ascent. Are you not decompressing on the ascent? The difference is MD doesn't separate the ascent segments in the plan. If you are planning a deco dive why do you care about ascents? You only care what the time of each deco stop is. Ascents are superfluous data and therefore MD doesn't show them. Since the ss is educational I show them. The NDL dive on the ss shows no deco time in the deco column but does show the no stop remaining for each segment of the dive. For every profile entered on the ss the ceiling is calculated and if it is 0 or negative NDL's are calculated. If the ceiling is positive it is a deco dive and a deco ascent schedule is generated showing the deco time for each segment. Since ascents are part of the deco ceiling calculation the time is included as part of the total deco time for the dive.

Each profile on the ss can contain up to four separate depths or way points. Safety stops are not automatically calculated since that limits the options for users. They can be entered as a separate depth using any time you want. The ss supports multilevel dives and repetitive dives. It supports up to five separate profiles. By making the profile's SI large you can isolate the profiles from one another.

 

[tomcatbubba]

Since it wasn’t on the list, 50/60.