Dive mode...

cavesam · 20th January 2010, 20:15

Should the Predator automatically go into dive mode when you splash in??

Mine does not. I was about 2 minutes into a dive and noticed that it was off so I turned it on and it started the dive from that point.

If it is not suposed to be this way maybe it was fixed in the latest release(it was 16 at the time)

if that is the design please see about changing this as almost all computers start automatically when you splash in.

Thanks

**Dsix36** · 20th January 2010, 21:59

And you didn't notice this in your predive check why?

cavesam · 20th January 2010, 22:14

Quote: (Originally Posted by Dsix36)

And you didn't notice this in your predive check why?

it was on but timed out during a surface talk and did not start back up once the dive started...

**Dsix36** · 21st January 2010, 00:12

Quote: (Originally Posted by cavesam)

it was on but timed out during a surface talk and did not start back up once the dive started...

I have had mine timeout while gearing up in the basin a couple of time also.

**dnscarboro** · 21st January 2010, 01:17

That means you guys are taking to long to gear up- if you had an air conditioned or heater trailer it would be no problem...

Sam you coming this weekend? I am lookin forward to getting wet again.

Not sure if Jeff told you I ordered a Shearwater last week... Just need to get hide it from my wife, the Nitex X and VR3 need new homes...

By the way, Dsix36 made my backplate had the right initials for the bottom of it....does great work later

bgpartri · 21st January 2010, 02:01

Quote: (Originally Posted by cavesam)

Should the Predator automatically go into dive mode when you splash in??

Mine does not. I was about 2 minutes into a dive and noticed that it was off so I turned it on and it started the dive from that point.
Thanks

It would have turned on if you let it. Once it has been at greater than 1300 mBar continuously for about 45 seconds, it will turn on. There is no need for it to turn on instantly, since a minute at 6 feet is not likely to have a big impact on your decompression profile.

Controllers will also turn on if they detect that they are in water, even in the absence of pressure.

Keep in mind that if you don't have it on when you start the dive it defeats the altitude function since it has no way to determine the pressure at the air/water interface.

Bruce

Web@Titan · 21st January 2010, 03:41

Quote: (Originally Posted by bgpartri)

... Once it has been at greater than 1300 mBar...

I believe Bruce meant 130 mbar.

jaksel · 21st January 2010, 06:43

Quote: (Originally Posted by Web@Titan)

I believe Bruce meant 130 mbar.

Are you sure? I think he means 1300 mbar absolute pressure, i.e. about 3 m (9 feet) depth.

cramerdn · 21st January 2010, 07:29

1300 millibars = 1.28300025 Atmospheres

bgpartri · 21st January 2010, 14:28

Yes, it is about 1300 mBar or 9 feet. There are several situations to consider.

First, if the Predator is turned on before the dive, it records the current pressure as the "surface pressure." It will go into dive mode at surface-pressure + 165 mBar as is specified by CE EN 13319. Since it knows the pressure at the air/water interface, depths will be calculated according to CE EN 13319 which is 1000 Bar = 10 meters. Note that this ratio does not reflect the density of either salt or fresh water. It is somewhere in between. (Dive computers don't measure linear depth. They measure pressure, and then use an offset for barometric pressure and an estimate of the density of the water. Decompression calculations are done in units of pressure and then displayed to the diver in approximations of depth.)

The second situation is that the Predator is not turned on at the start of the dive. It checks every few seconds to determine if the current pressure has reached 1300 mBar. If it sees 1300 mBar it waits for a while to confirm that this isn't just a giant stride from the MV Karin, or into Stargate cave. Then, since this pressure is not possible on the surface, we must be diving. (The highest surface pressure ever recorded is 1085.6 mBar.) It turns on, and since it cannot determine the pressure at the air/water interface, it sets the surface pressure to 1013. Note that depths will be offset by the difference between the actual surface pressure and 1013, so it is important to have the computer turned on when you start the dive if you are diving at altitude.

The third situation is that the computer is is turned on while on a commercial airline. It will (incorrectly) set the cabin pressure (about 800 mBar) as surface pressure. If the turn-on pressure was less than 1300 mBar, the computer would turn on when it returned to surface pressure (nominally 1013) and would stay on until the battery was removed. That is what Pursuits do now and that will be changed to match the Predator in the next version of Pursuit firmware.

Bruce

20th January 2010, 20:15	#1 (permalink)
cavesam RBW Member Optima Join Date: Mar 2009 Location: GA Posts: 19	Dive mode... Should the Predator automatically go into dive mode when you splash in?? Mine does not. I was about 2 minutes into a dive and noticed that it was off so I turned it on and it started the dive from that point. If it is not suposed to be this way maybe it was fixed in the latest release(it was 16 at the time) if that is the design please see about changing this as almost all computers start automatically when you splash in. Thanks
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20th January 2010, 21:59	#2 (permalink)
Dsix36 Going Down? rEvo Optima Dolphin Join Date: Aug 2007 Location: Deerfield_Beach, Florida Posts: 2,238	Re: Dive mode... And you didn't notice this in your predive check why? __________________ THE MORE THAT I LEARN, THE MORE THAT I STILL NEED TO LEARN!!!!!!
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20th January 2010, 22:14	#3 (permalink)
cavesam RBW Member Optima Join Date: Mar 2009 Location: GA Posts: 19	Re: Dive mode... Quote: (Originally Posted by Dsix36) And you didn't notice this in your predive check why? it was on but timed out during a surface talk and did not start back up once the dive started...
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21st January 2010, 00:12	#4 (permalink)
Dsix36 Going Down? rEvo Optima Dolphin Join Date: Aug 2007 Location: Deerfield_Beach, Florida Posts: 2,238	Re: Dive mode... Quote: (Originally Posted by cavesam) it was on but timed out during a surface talk and did not start back up once the dive started... I have had mine timeout while gearing up in the basin a couple of time also. __________________ THE MORE THAT I LEARN, THE MORE THAT I STILL NEED TO LEARN!!!!!!
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21st January 2010, 01:17	#5 (permalink)
dnscarboro Supporting Member Join Date: May 2007 Location: Atlanta, GA Posts: 76	Re: Dive mode... That means you guys are taking to long to gear up- if you had an air conditioned or heater trailer it would be no problem...Sam you coming this weekend? I am lookin forward to getting wet again. Not sure if Jeff told you I ordered a Shearwater last week... Just need to get hide it from my wife, the Nitex X and VR3 need new homes... By the way, Dsix36 made my backplate had the right initials for the bottom of it....does great work later __________________ *“Obstacles are things a person sees when he takes his eyes off his goal.”*
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21st January 2010, 02:01	#6 (permalink)
bgpartri CEO-Shearwater Megalodon CCR2000,KISS,Inspo,Dolphin Join Date: Apr 2005 Location: Vancouver, Canada Posts: 565	Re: Dive mode... Quote: (Originally Posted by cavesam) Should the Predator automatically go into dive mode when you splash in?? Mine does not. I was about 2 minutes into a dive and noticed that it was off so I turned it on and it started the dive from that point. Thanks It would have turned on if you let it. Once it has been at greater than 1300 mBar continuously for about 45 seconds, it will turn on. There is no need for it to turn on instantly, since a minute at 6 feet is not likely to have a big impact on your decompression profile. Controllers will also turn on if they detect that they are in water, even in the absence of pressure. Keep in mind that if you don't have it on when you start the dive it defeats the altitude function since it has no way to determine the pressure at the air/water interface. Bruce __________________ http://www.shearwaterresearch.com Good judgment comes from experience. Experience comes from bad judgment.
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21st January 2010, 03:41	#7 (permalink)
Web@Titan RBW Member Join Date: Feb 2009 Posts: 36	Re: Dive mode... Quote: (Originally Posted by bgpartri) ... Once it has been at greater than 1300 mBar... I believe Bruce meant 130 mbar. Last edited by Web@Titan : 21st January 2010 at 03:44.
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21st January 2010, 06:43	#8 (permalink)
jaksel Jakob Selbing AP Evolution+ Join Date: Oct 2008 Location: Stockholm Posts: 131	Re: Dive mode... Quote: (Originally Posted by Web@Titan) I believe Bruce meant 130 mbar. Are you sure? I think he means 1300 mbar absolute pressure, i.e. about 3 m (9 feet) depth.
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21st January 2010, 07:29	#9 (permalink)
cramerdn Banned Join Date: Dec 2006 Posts: 1,659	Re: Dive mode... 1300 millibars = 1.28300025 Atmospheres
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21st January 2010, 14:28	#10 (permalink)
bgpartri CEO-Shearwater Megalodon CCR2000,KISS,Inspo,Dolphin Join Date: Apr 2005 Location: Vancouver, Canada Posts: 565	Re: Dive mode... Yes, it is about 1300 mBar or 9 feet. There are several situations to consider. First, if the Predator is turned on before the dive, it records the current pressure as the "surface pressure." It will go into dive mode at surface-pressure + 165 mBar as is specified by CE EN 13319. Since it knows the pressure at the air/water interface, depths will be calculated according to CE EN 13319 which is 1000 Bar = 10 meters. Note that this ratio does not reflect the density of either salt or fresh water. It is somewhere in between. (Dive computers don't measure linear depth. They measure pressure, and then use an offset for barometric pressure and an estimate of the density of the water. Decompression calculations are done in units of pressure and then displayed to the diver in approximations of depth.) The second situation is that the Predator is not turned on at the start of the dive. It checks every few seconds to determine if the current pressure has reached 1300 mBar. If it sees 1300 mBar it waits for a while to confirm that this isn't just a giant stride from the MV Karin, or into Stargate cave. Then, since this pressure is not possible on the surface, we must be diving. (The highest surface pressure ever recorded is 1085.6 mBar.) It turns on, and since it cannot determine the pressure at the air/water interface, it sets the surface pressure to 1013. Note that depths will be offset by the difference between the actual surface pressure and 1013, so it is important to have the computer turned on when you start the dive if you are diving at altitude. The third situation is that the computer is is turned on while on a commercial airline. It will (incorrectly) set the cabin pressure (about 800 mBar) as surface pressure. If the turn-on pressure was less than 1300 mBar, the computer would turn on when it returned to surface pressure (nominally 1013) and would stay on until the battery was removed. That is what Pursuits do now and that will be changed to match the Predator in the next version of Pursuit firmware. Bruce __________________ http://www.shearwaterresearch.com Good judgment comes from experience. Experience comes from bad judgment.
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