Shearwater Pursuit versus VR3

Steve-M · 25th July 2008, 20:56

Okay ... here is where I show my ignorance and complacency.

I've had the VR 3 for many years and I've been very comfortable diving on it with a number of different rebreathers (Inspiration, Classic KISS, Sport KISS and Evolution) as well as open circuit air/nitrox/trimix. From memory it has a percent conservatism that you can set. It's so long since I set this that I can't remember what I normally use. I think it's a fairly low conservatism ... maybe 20% but I'm not really sure. It's never got me bent and is not something I think too much about on a dive-dive basis.

Now I have got the new Shearwater and I have got to think about gradient factors. Actually ... I already had them with the Evolution Vision, but I just accepted the default and went diving with it. I've seen the papers by Erik Bakker and have got the gist of them without claiming a 100% understanding.

The question is this: what gradient factors are sensible/healthy to use? The default for the Evolution is (I think) 15/85. I set the Shearwater the same just to avoid any discrepancy between the two.

What gradient factors do other divers use and why? That's the question that is puzzling me and is not best covered in any of the technical papers. Why would you want to change the gradient factors from one dive to the next? ... or do you just pick a number (two numbers actually) and then hope that you are lucky and stick with it?

Quote: (Originally Posted by divetheworld)

Decompression using Gradient factors.

Nuff said.

Mark Chase · 25th July 2008, 21:13

Quote: (Originally Posted by Steve-M)

Okay ... here is where I show my ignorance and complacency.

I've had the VR 3 for many years and I've been very comfortable diving on it with a number of different rebreathers (Inspiration, Classic KISS, Sport KISS and Evolution) as well as open circuit air/nitrox/trimix. From memory it has a percent conservatism that you can set. It's so long since I set this that I can't remember what I normally use. I think it's a fairly low conservatism ... maybe 20% but I'm not really sure. It's never got me bent and is not something I think too much about on a dive-dive basis.

Now I have got the new Shearwater and I have got to think about gradient factors. Actually ... I already had them with the Evolution Vision, but I just accepted the default and went diving with it. I've seen the papers by Erik Bakker and have got the gist of them without claiming a 100% understanding.

The question is this: what gradient factors are sensible/healthy to use? The default for the Evolution is (I think) 15/85. I set the Shearwater the same just to avoid any discrepancy between the two.

What gradient factors do other divers use and why? That's the question that is puzzling me and is not best covered in any of the technical papers. Why would you want to change the gradient factors from one dive to the next? ... or do you just pick a number (two numbers actually) and then hope that you are lucky and stick with it?

20/80 is a good start point. Prety much the same in terms of overall run time as the VR3 on zero safety but a totaly diferent way of getting there.

You will find the single very very deep stop goes away and more intermediate stops apear. It works well with both helium and nitrox dives.

I dive 10/90 now and I extend the shalow stops if i feel a bit off colour on the day or if its been a hard dive. IE clear the computer at 6 and spend 5 -10mins geting up from there.

HTH

ATB

Mark

Steve-M · 28th July 2008, 10:06

Thanks for the reply. That makes sense. I guess that the default 15/85 that the Evolution uses is not a bad start point.

cheers

Quote: (Originally Posted by Mark Chase)

20/80 is a good start point. Prety much the same in terms of overall run time as the VR3 on zero safety but a totaly diferent way of getting there.

You will find the single very very deep stop goes away and more intermediate stops apear. It works well with both helium and nitrox dives.

I dive 10/90 now and I extend the shalow stops if i feel a bit off colour on the day or if its been a hard dive. IE clear the computer at 6 and spend 5 -10mins geting up from there.

HTH

ATB

Mark

zoo_diver · 28th July 2008, 10:32

Quote: (Originally Posted by cramerdn)

Its like buying a six pack and finding out its got 10 year old flat american beer in the two cans.

Anyone who would ever consider spending money on a VR3 that could be spent on a Pursuit is a snorkel wearing fool.

you said "snorkel wearing fool" --- nice!

cramerdn · 28th July 2008, 12:53

Quote: (Originally Posted by zoo_diver)

you said "snorkel wearing fool" --- nice!

And now that you said it, you owe me a nickel.

Snorkel Wearing Fools™

Rickoz · 29th July 2008, 08:15

I've had a vr3 since about 2001 & luv it.
Having said that i my next tool for monitoring i think will be the
ShearWater Pursuit.

Sorry but i'll add one more Question.

What Deco software comes close to the Pursuits Algorithm.

Well 2 Questions.

And can it be used on a Apple

Rickoz

Rob Dobson · 29th July 2008, 10:22

Quote: (Originally Posted by Rickoz)

And can it be used on a Apple

Rickoz

No, which is why I'm going to be putting BootCamp on my Mac later today. S/W updates are via infra red USB which runs from PC.

Mark Chase · 29th July 2008, 10:32

Quote: (Originally Posted by Rickoz)

I've had a vr3 since about 2001 & luv it.
Having said that i my next tool for monitoring i think will be the
ShearWater Pursuit.

Sorry but i'll add one more Question.

What Deco software comes close to the Pursuits Algorithm.

Well 2 Questions.

And can it be used on a Apple

Rickoz

It doesn't come with planning software you will need a GF based deco program like Nautilus. I only plan my OC bailout so i use Decoplanner.

It does have a very inexpensive dive log system which is a PITA to organize a dive history on but gives excellent graphs of the dive.

ATB

Mark

cronix · 29th July 2008, 12:34

Quote: (Originally Posted by Rob Dobson)

No, which is why I'm going to be putting BootCamp on my Mac later today. S/W updates are via infra red USB which runs from PC.

There is no need to run BootCamp. I am using Parallels Desktop on top of OSX. That way I can run GAP and the Shearwater download software.

Rob Dobson · 29th July 2008, 17:06

Quote: (Originally Posted by cronix)

There is no need to run BootCamp. I am using Parallels Desktop on top of OSX. That way I can run GAP and the Shearwater download software.

Right... So how do you get that to work with the USB > IR adapter for the S/W updates?

25th July 2008, 20:56	#11 (permalink)
Steve-M RBW Member Current Rebreather/s: Evolution Sport Kiss Other Rebreather/s: Inspiration Classic Inspiration Vision Prism Topaz Classic Kiss MK 15.X Ouroboros Join Date: Jul 2006 Location: Liverpool Posts: 48	Re: Shearwater Pursuit versus VR3 Okay ... here is where I show my ignorance and complacency. I've had the VR 3 for many years and I've been very comfortable diving on it with a number of different rebreathers (Inspiration, Classic KISS, Sport KISS and Evolution) as well as open circuit air/nitrox/trimix. From memory it has a percent conservatism that you can set. It's so long since I set this that I can't remember what I normally use. I think it's a fairly low conservatism ... maybe 20% but I'm not really sure. It's never got me bent and is not something I think too much about on a dive-dive basis. Now I have got the new Shearwater and I have got to think about gradient factors. Actually ... I already had them with the Evolution Vision, but I just accepted the default and went diving with it. I've seen the papers by Erik Bakker and have got the gist of them without claiming a 100% understanding. The question is this: what gradient factors are sensible/healthy to use? The default for the Evolution is (I think) 15/85. I set the Shearwater the same just to avoid any discrepancy between the two. What gradient factors do other divers use and why? That's the question that is puzzling me and is not best covered in any of the technical papers. Why would you want to change the gradient factors from one dive to the next? ... or do you just pick a number (two numbers actually) and then hope that you are lucky and stick with it? Quote: (Originally Posted by divetheworld) Decompression using Gradient factors. Nuff said. __________________ Steve-M
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25th July 2008, 21:13	#12 (permalink)
Mark Chase RBW Member Current Rebreather/s: Classic Kiss Other Rebreather/s: Inspiration Classic Join Date: Jan 2005 Location: Kent Posts: 2,854	Re: Shearwater Pursuit versus VR3 Quote: (Originally Posted by Steve-M) Okay ... here is where I show my ignorance and complacency. I've had the VR 3 for many years and I've been very comfortable diving on it with a number of different rebreathers (Inspiration, Classic KISS, Sport KISS and Evolution) as well as open circuit air/nitrox/trimix. From memory it has a percent conservatism that you can set. It's so long since I set this that I can't remember what I normally use. I think it's a fairly low conservatism ... maybe 20% but I'm not really sure. It's never got me bent and is not something I think too much about on a dive-dive basis. Now I have got the new Shearwater and I have got to think about gradient factors. Actually ... I already had them with the Evolution Vision, but I just accepted the default and went diving with it. I've seen the papers by Erik Bakker and have got the gist of them without claiming a 100% understanding. The question is this: what gradient factors are sensible/healthy to use? The default for the Evolution is (I think) 15/85. I set the Shearwater the same just to avoid any discrepancy between the two. What gradient factors do other divers use and why? That's the question that is puzzling me and is not best covered in any of the technical papers. Why would you want to change the gradient factors from one dive to the next? ... or do you just pick a number (two numbers actually) and then hope that you are lucky and stick with it? 20/80 is a good start point. Prety much the same in terms of overall run time as the VR3 on zero safety but a totaly diferent way of getting there. You will find the single very very deep stop goes away and more intermediate stops apear. It works well with both helium and nitrox dives. I dive 10/90 now and I extend the shalow stops if i feel a bit off colour on the day or if its been a hard dive. IE clear the computer at 6 and spend 5 -10mins geting up from there. HTH ATB Mark __________________ See my "Doing It Chasey" video where I'm locked into a padded room, naked, with two ball bearings and within an Hour, I manage to lose one and break the other!!! Kevin Juergensen 16/11/08 [/quote]
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28th July 2008, 10:06	#13 (permalink)
Steve-M RBW Member Current Rebreather/s: Evolution Sport Kiss Other Rebreather/s: Inspiration Classic Inspiration Vision Prism Topaz Classic Kiss MK 15.X Ouroboros Join Date: Jul 2006 Location: Liverpool Posts: 48	Re: Shearwater Pursuit versus VR3 Thanks for the reply. That makes sense. I guess that the default 15/85 that the Evolution uses is not a bad start point. cheers Quote: (Originally Posted by Mark Chase) 20/80 is a good start point. Prety much the same in terms of overall run time as the VR3 on zero safety but a totaly diferent way of getting there. You will find the single very very deep stop goes away and more intermediate stops apear. It works well with both helium and nitrox dives. I dive 10/90 now and I extend the shalow stops if i feel a bit off colour on the day or if its been a hard dive. IE clear the computer at 6 and spend 5 -10mins geting up from there. HTH ATB Mark __________________ Steve-M
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28th July 2008, 10:32	#14 (permalink)
zoo_diver Is it snack time yet? Current Rebreather/s: Evolution Megalodon Sport Kiss Other Rebreather/s: Megalodon Join Date: Jun 2007 Location: Suffolk, VA Posts: 259	Re: Shearwater Pursuit versus VR3 Quote: (Originally Posted by cramerdn) Its like buying a six pack and finding out its got 10 year old flat american beer in the two cans. Anyone who would ever consider spending money on a VR3 that could be spent on a Pursuit is a snorkel wearing fool. you said "snorkel wearing fool" --- nice!
(Offline)

28th July 2008, 12:53	#15 (permalink)
cramerdn Obey my dog! Current Rebreather/s: Evolution Dolphin Other Rebreather/s: Dolphin Join Date: Dec 2006 Location: Townsville QLD Posts: 730	Re: Shearwater Pursuit versus VR3 Quote: (Originally Posted by zoo_diver) you said "snorkel wearing fool" --- nice! And now that you said it, you owe me a nickel. Snorkel Wearing Fools™ __________________ "Its better to live one day as a tiger than an entire life as a worm." "But who's ever heard of a worm skin rug?" Last edited by cramerdn : 28th July 2008 at 12:55.
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29th July 2008, 08:15	#16 (permalink)
Rickoz KISS Rebreather Pilot 109 Current Rebreather/s: Classic Kiss Other Rebreather/s: Join Date: Feb 2005 Location: Australia Posts: 168	Re: Shearwater Pursuit versus VR3 I've had a vr3 since about 2001 & luv it. Having said that i my next tool for monitoring i think will be the ShearWater Pursuit. Sorry but i'll add one more Question. What Deco software comes close to the Pursuits Algorithm. Well 2 Questions. And can it be used on a Apple Rickoz __________________ Rickoz http://www.rebreatherworld.com/gener...sland-r-u.html
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29th July 2008, 10:22	#17 (permalink)
Rob Dobson RBW Member Current Rebreather/s: Megalodon Other Rebreather/s: Join Date: Dec 2007 Location: Oxford Posts: 100	Re: Shearwater Pursuit versus VR3 Quote: (Originally Posted by Rickoz) And can it be used on a Apple Rickoz No, which is why I'm going to be putting BootCamp on my Mac later today. S/W updates are via infra red USB which runs from PC. Last edited by Rob Dobson : 29th July 2008 at 10:48. Reason: Oops - completely misread the 1st part of the question...
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29th July 2008, 10:32	#18 (permalink)
Mark Chase RBW Member Current Rebreather/s: Classic Kiss Other Rebreather/s: Inspiration Classic Join Date: Jan 2005 Location: Kent Posts: 2,854	Re: Shearwater Pursuit versus VR3 Quote: (Originally Posted by Rickoz) I've had a vr3 since about 2001 & luv it. Having said that i my next tool for monitoring i think will be the ShearWater Pursuit. Sorry but i'll add one more Question. What Deco software comes close to the Pursuits Algorithm. Well 2 Questions. And can it be used on a Apple Rickoz It doesn't come with planning software you will need a GF based deco program like Nautilus. I only plan my OC bailout so i use Decoplanner. It does have a very inexpensive dive log system which is a PITA to organize a dive history on but gives excellent graphs of the dive. ATB Mark __________________ See my "Doing It Chasey" video where I'm locked into a padded room, naked, with two ball bearings and within an Hour, I manage to lose one and break the other!!! Kevin Juergensen 16/11/08 [/quote]
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29th July 2008, 12:34	#19 (permalink)
cronix New Member Current Rebreather/s: rEvo Other Rebreather/s: Inspiration Classic rEvo Join Date: Aug 2006 Location: the Netherlands Posts: 39	Re: Shearwater Pursuit versus VR3 Quote: (Originally Posted by Rob Dobson) No, which is why I'm going to be putting BootCamp on my Mac later today. S/W updates are via infra red USB which runs from PC. There is no need to run BootCamp. I am using Parallels Desktop on top of OSX. That way I can run GAP and the Shearwater download software. __________________ You can never get close enough to get a good picture
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29th July 2008, 17:06	#20 (permalink)
Rob Dobson RBW Member Current Rebreather/s: Megalodon Other Rebreather/s: Join Date: Dec 2007 Location: Oxford Posts: 100	Re: Shearwater Pursuit versus VR3 Quote: (Originally Posted by cronix) There is no need to run BootCamp. I am using Parallels Desktop on top of OSX. That way I can run GAP and the Shearwater download software. Right... So how do you get that to work with the USB > IR adapter for the S/W updates?
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