Learning about my Freedive Recovery Vest

[Bill McIntyre]

I had an interesting experience today and was puzzled for a while. Maybe it will be of value to someone as dumb as I am, and the rest of you can think (or even say if you wish) "any dummy should have known that."

Just in case you don't know, the Freedive Recovery Vest can be programmed to automatically inflate if you exceed your user-selected trigger time or depth.

I had been diving for about 30 minutes and my best dives were about 15 seconds shorter than the trigger time I've set in my FRV. Then for some reason, I felt super relaxed and my next dive was 11 seconds longer, or only 4 seconds shorter than my trigger time. I wish I could figure out why I improved so much so that I could duplicate it in the future, but that isn't the point of this story.

Then I felt so good on the next dive that I improved by 5 more seconds, which meant that I exceeded my trigger time by a second. I swam back to the boat to verify my trigger time, and it was what I thought it was. So then I wondered why the vest had not inflated. I suspected that it might be because the Aeris F.10 watch started counting dive time at a shallower depth than the FRV, but I wasn't sure. I increased my trigger time by 10 seconds and continued diving, but was even more conservative than usual.

Now that I'm home, I checked the on-line manuals. Sure enough, the FRV starts timing a dive at 6 feet and ends the dive when you ascend to 3 feet. The watch start depth can be set for 2 feet, 4 feet, or 6 feet, but the factory default is 2 feet, and my watch is set for 2 feet. That means that my FRV will time a dive slightly shorter than my watch. The difference must be what saved me from an inadvertent inflation.

I'm not sure what you can do with this information, but I thought I'd pass it along.

 

[Stephan Whelan]

Bill - interesting info - you given the info to Terry Maas?

 

[Bill McIntyre]

Bill - interesting info - you given the info to Terry Maas?

Yes I did. He said he just got an Aeris watch, so he was aware of the difference in depth at which timing started.

 

[Jon]

Sounds like a simple difference in programing. I know that in my tech diving days I had two different computers that would be off as much as 6' on a deep dive, but that was due to one being calibrated salt water and the other to fresh water. Once I did the calculation i realized they were both reading the same pressure, just different depths because they were set to different water densities. I'm not sure how the vest would be able to accommodate all of the different watches on the market.

Jon

 

[Bill McIntyre]

The vest couldn't possibly accommodate all the different watches, and I don't think its a big deal anyway. If the vest starts timing a dive at 6 feet and my watch starts at 2 feet, how much is the difference in time? Unless you start dives very slowly, its insignificant.

I only brought this up in case someone happened to have a dive fit in that narrow window so that he wondered why his vest didn't inflate even though his watch said he exceeded the trigger time. If, for instance, I had a trigger time set for 1:30 and my watch read 1:32 when the vest actually inflated, I doubt that my body would notice.

 

[Bill McIntyre]

Today I had an interesting experience that is probably a function of age. My wife gave me a day off from helping her get around with a broken ankle and let me go diving. She probably figured that it in the long run, it was better to let me go today so that I wouldn't leave her in a dumpster tomorrow. Whatever.


Anyway, I was passing 33 feet feeling very good about my great diving when my FRV inflated and gave me a rapid trip to the surface.


When I got back to the boat, I checked the actuator. It gives you a reason for any inflation and in this case it read “d 10.” That means that it inflated because I exceeded 10 meters. I checked my trigger depth setting, and sure enough it was set at 10 meters. I just couldn’t understand why I would have done that.


After a lot of soul-searching, I came up with the explanation that I’m going to stick with.


Most of the places I dive are from 40 to 55 feet deep. I want to be able to get to the bottom to retrieve a fish, so I set my trigger depth at 60 feet.


For most of my life, depths were expressed in either feet or fathoms. Nautical charts are still marked in fathoms. Meters are a relatively new measurement of depth in the US, and mostly used by foo-foo pure freedivers trying to sound European.


So anyway, here is my story. I sent my FRV back to Terry Maas to be converted to the new streamlined configuration, and I had to reenter my times and depth triggers when I got it back.. I must have had a brain fart and been thinking of fathoms rather than meters when I entered 10. Ten fathoms is 60 feet. It’s the only plausible explanation. I’m not so bad at math that I would have equated 10 meters with 60 feet. Really, not yet.


I doubt that anyone younger than dirt will make this mistake, but just in case I’m trying to be helpful.