GPS and time to fly - questions

[tarjan]

In the dive log, there is an option for gps coordinate entry. Sounds good, but there is also an X'ed out GPS button. I am guessing this is for future functionality. Anyone know if this is for future use with a purchased add on or is it something just disabled for now?

Second, time to fly. I had 4.5hrs fly, 17hrs desat on the clock. 22hrs before my flight and it was time to make a decision on diving or not.

One hour 25-40ft dive. Without the dive planner, I didn't want to start chancing anything so I did not dive though I am 100% sure the no fly time would still have been in the proper time range, though not full desat. That being said, the fly time calculator seems to be MUCH less than the standards I have read about elsewhere. Normally 18 hrs for one dive, 24 for multiples.

I'll admit, rule of thumb is conservative to a fault, but doing a series of boat dives (though with a 24hr period of no diving so I was desat before the days dive) over days and being told I can fly 4 hour hours after a dive that hit mid 80' depths for a short time seems... Odd.

So I want more information about how fly time is calculated and want to understand why it says it is safe to fly.

Are there studies done describing the calculation methods? I mean seriously, buying some extra time to be on land a bit more after a dive is great, but not always in the cards. I want to maximize my time making bubbles while not adding any real risks to my dives. If there is method to the madness and it is actually "safe" to make that one last dive, I want to make that one last dive!!!

 

[DiverLaura]

you can enter coordinates in

Database -> Divespots -> GPS Data

the "X" is to clear the coordinates that you entered.

you can also enter coordinates in myuemis log, and the dive community and portal coordinates back and forth via al three (SDA, Myuemis, myworld)

I will find out the time to fly information.

 

[tarjan]

One more thing, and this might be a serious bug.

When I came out of my dive, my device showed my post dive status as max altitude as around 10k feet. On the myuemis site it shows my max altitude as 3500 feet. I made sure I was reading that right, it did say feet. This could be a conversion issue, feet vs metric BUT I wanted to point it out just in case it is something else.

That's a safety item and needs to be correct.

 

[DiverLaura]

it is a conversion issue on the myuemis side, i'll pass it on. The "feet/meters" converstion in the computer is correct, it was updated in 1.2. Thanks for pointing it out...

 

[reo]

One more thing, and this might be a serious bug.

When I came out of my dive, my device showed my post dive status as max altitude as around 10k feet. On the myuemis site it shows my max altitude as 3500 feet. I made sure I was reading that right, it did say feet. This could be a conversion issue, feet vs metric BUT I wanted to point it out just in case it is something else.

That's a safety item and needs to be correct.

3500 meters equals 11483 feet. This could be an issue with myuemis displaying meters as feet. It used to be an issue on the SDA itself, but was fixed with v1.2. I'm diving on Tuesday and I'll pay attention to the Max Alt immediately after the dive and then see what displays on myuemis after syncing. Stay tuned.

Ron

Edit: I was interrupted while posting this. When I returned and finished, Laura's post above mine answered the question. Oh well...

 

[ijdod]

For what it's worth, the no-fly counter on my SDA is more conservative than my Suunto Vyper2.

 

[DiverLaura]

tarjan, is your computer running the latest firmware? (1.2)

From Ernst:

Flying after diving is a continuation of the decompression, as the ambient pressure drops below the surface pressure. Usually, the cabin pressure in an air plane at cruising level is about equal to a pressure in an altitude of 2’000 m (6’500 ft) above sea level. Theoretically one could fly, when the allowed altitude equals 6’500 ft (with no safety margin).

In the decompression model Uemis ZH-L8+, the cabin pressure used for the “do not fly time” calculation is equal to a pressure in an altitude of about 17’000 ft for safety reasons (at that pressure drop, the airplane would already be in a rapid descent and passengers would be breathing out of the oxygen masks).

The “official” rules for the “do not fly time” do not take in account the actual inert gas in the diver’s body. The basis for these rules are worst case scenarios and do even take in account the possibility of flying in non pressurized small air planes. The SDA will calculate the “do not fly time” with the calculated inert gas loading of the tissues. Therefore, our do not fly time will normally be shorter than the official rules.

 

[tarjan]

Great answers! Of course it means I really should have been fine on the dive with the big green moray eel. Live and learn!

I am definitely on 1.2 as well. Can't wait for the dive planner mode as well though I would also like to see an external GPS to put the coordinates in for me . Otherwise if anyone is interested, the easy way to do it is to get a camera/cameraphone that supports geotagging. Just take a picture of the dive site with the geotagging turned on. It will then store the time and the location in the exif data, easy to pull out later at your leisure.

I came to that conclusion a bit late for this trip

 

[reo]

3500 meters equals 11483 feet. This could be an issue with myuemis displaying meters as feet. It used to be an issue on the SDA itself, but was fixed with v1.2. I'm diving on Tuesday and I'll pay attention to the Max Alt immediately after the dive and then see what displays on myuemis after syncing. Stay tuned.

Ron

Edit: I was interrupted while posting this. When I returned and finished, Laura's post above mine answered the question. Oh well...

I've compared the Max Altitude found on my SDA logbook to the Allowed Altitude on the Pre/Post Dive Decompression data on MyUemis. For all the dives I've checked, the Max Altitude number is 2.54 times the Allowed Altitude number. These results are for Imperial numbers.

Ben B, maybe you could post your results using metric numbers.

I believe the error to be in MyUemis as Laura mentioned in a previous post.

I've opened a ticket on MyUemis.

Ron

 

[BB1]

I've compared the Max Altitude found on my SDA logbook to the Allowed Altitude on the Pre/Post Dive Decompression data on MyUemis. For all the dives I've checked, the Max Altitude number is 2.54 times the Allowed Altitude number. These results are for Imperial numbers.

Ben B, maybe you could post your results using metric numbers.

I believe the error to be in MyUemis as Laura mentioned in a previous post.

I've opened a ticket on MyUemis.

Ron

No worries, I will check back over last weekends data and make sure to have a good look at Sundays dive data.

I'll report back asap.