SMI Prism training

***jradomski*** · 12th December 2005, 22:27

Quote: (Originally Posted by caveseeker7)

Thanks for laying that out, Joe.

The 3/3 setup is good to have, especially when it's all you got.
The independent and separate electronic and analog combo of the PRISM
and MK are my preference, that's probably the only thing where we differ.
You prefer lots of features and options, I prefer simplicity.

I was trying to figure out Why you thought I was attacking the PRISM.. I still don;t see it.. All I said is I wouldn;t dive with just a secondary... I never mentioned a specific unit..

The HH, MK15, Prism all use the term secondary.. Just one operational now effectively makes it a primary, without all the functions intended for a primary...

Genesis · 12th December 2005, 22:29

Uh, there is an emergency pedal on every car I've been in (or an emergency lever.) Its called the parking brake, and while it only actuates two of the 4 wheel brakes (and the weakest two for stopping a moving vehicle at that) it WILL bring you to a stop and is on a completely-indepedant cable linkage from the service brake hydraulic circuit.

Bad example

***jradomski*** · 12th December 2005, 22:29

Quote: (Originally Posted by silent running)

Hi Joe, about this redundancy thing, I think it's worth considering the ways in which things most likely fail. I don't know of any Prism 2ndrys failing underwater. Why? Because there is really nothing to go wrong, especially when the power is off. I do know of many, many Kiss displays flooding or getting wet enough to not work. I'm not saying that having 3 separate Kiss displays is a bad idea, obviously it works and is a necessary part of the design, which is overall, very safe. But I don't think the "1 display is 1 display" thing takes everything into account.
Remember, there is only one brake pedal in your car, what if the mechanical linkage somehow came apart? You'd crash. And this does happen once in a great while. But not enough to have everybody demanding an emergency pedal be made part of the design. Everything carries risk, there are ones which are acceptable to most people and ones which are not. And of course reasonable people can disagree... -Andy

When it comes to life support equipment underwater I tend to error on the side of caution.. There is always tomorrow to make a dive.. Inmy mind no dive has to be done today (unless you were going to rescue someone, the I would do whatever was necessary)..

Genesis,
You beat me to the "emergency" brake..

silent running · 12th December 2005, 22:39

Quote: (Originally Posted by Genesis)

Uh, there is an emergency pedal on every car I've been in (or an emergency lever.) Its called the parking brake, and while it only actuates two of the 4 wheel brakes (and the weakest two for stopping a moving vehicle at that) it WILL bring you to a stop and is on a completely-indepedant cable linkage from the service brake hydraulic circuit.

Bad example

Hi Genesis, I understand your point, but pulling the parking brake lever aint gonna do much when you're doing 70 mph down a hill. That's why they have those runaway vehicle ramps on highways here in the US. Not to mention that the average person would likely panic and freeze up and not even think of applying the parking brake...But I digress further... -Andy

***jradomski*** · 12th December 2005, 22:42

Quote: (Originally Posted by silent running)

Hi Joe, about this redundancy thing, I think it's worth considering the ways in which things most likely fail. I don't know of any Prism 2ndrys failing underwater. Why? Because there is really nothing to go wrong, especially when the power is off. I do know of many, many Kiss displays flooding or getting wet enough to not work. I'm not saying that having 3 separate Kiss displays is a bad idea, obviously it works and is a necessary part of the design, which is overall, very safe. But I don't think the "1 display is 1 display" thing takes everything into account.
Remember, there is only one brake pedal in your car, what if the mechanical linkage somehow came apart? You'd crash. And this does happen once in a great while. But not enough to have everybody demanding an emergency pedal be made part of the design. Everything carries risk, there are ones which are acceptable to most people and ones which are not. And of course reasonable people can disagree... -Andy

I'm not disagreeing with levels of failure.. when you dove with just the secondary, did you check all 3 cells everytime you checked your display, if not its no better than just having one cell.. since you have no way of knowing without checking that the one cell is correct..

There is still the possiblity of banging the secondary against something underwater.. (we all have goten surprised by surge at one time or another)

There is a chance of entanglement.. I knwo I wouldn;t hesitate cutting my cable to one of my handsets If I had to.. with 1 operational it now makes it a difficult choice.. This one think I will miss on the new HH, my old one had removable handsets, and ONCE I got entangled and couldn;t see where it got hooked.. I just said to myself screw it,unhooked the cable and aborted the dive on the remaining handset... If I was down to one I would have had to find how and where it got entangled..

Underwaterbear · 12th December 2005, 22:48

Quote: (Originally Posted by caveseeker7)

...snip

I agree that Rebreather users should have a 'save-the-dive' kit available, just as most divers do. SMI offers it for the PRISM, they'll provide advice individually as to what it should contain based on the diving profiles and locations. I don't know if anyone in Oz bothered to get one, including the importer.
...snip

Well, actually we wound up with a whole unit as a spare parts rig

and we needed it.

As has been mentioned around here before...to be totally frank, the ten units shipped to Oz, in combination, had what I and others considered a very large number of problems ranging from minor assembly issues to major failures of components and to top it all off a very unusual software glitch that wasn't caught until way too late in my personal opinion.

Despite all these problems all 9 users were able to dive their units after some canibalisation, repair, rebuilding.

Put these problems down to the move to TN... yeah maybe (still should have caught the assembly and s/w glitches). Put them down to the other "issues" with the whole deal...probably a factor. Put the fact users were slow to pick up later issues down to an inexperienced instructor staright from his course...probably a factor.

How big a deal was the fact we are 4 days by air freight from the factory? Not nearly as big a problem as the human factors involved.

Bottom line: Not one commercial Rebreather manufacturer has anything like the support capacity of a major corporation, SMI are no different. The unit has it's idiosyncracies (they all do), but is a very well designed Rb that is a pleasure to dive...in the water it's easily the best I've tried. There are not many things you can do that will keep the unit out of the water...even my catastrophically smashed head could have been glued back together with epoxy and probably dived had it been more crucial for me to do so. Final note...carry a small range of common spares and at the end of the day there is hardly a spot on the planet Fed Ex can't get to.

Cheers
Andrew

Genesis · 12th December 2005, 22:52

Quote: (Originally Posted by silent running)

Hi Genesis, I understand your point, but pulling the parking brake lever aint gonna do much when you're doing 70 mph down a hill. That's why they have those runaway vehicle ramps on highways here in the US. Not to mention that the average person would likely panic and freeze up and not even think of applying the parking brake...But I digress further... -Andy

I know we're off-topic here but the ramps are for trucks, which have pneumatically-operated brakes that DO NOT work like those in your car - they are completely different both in how they normally work and in their failure modes and effects.

A properly adjusted passenger car parking brake WILL stop a car going down a hill at 70mph. It will take quite a distance, but it will stop you; the parking brake is (if properly adjusted) quite capable of locking the rear wheels.

(Speaking as someone who has done more than a few "J" turns in his car over the years..... that maneuver REQUIRES a properly-working handbrake - and who HAS had to stop using the parking brake before (don't ask!))

Anyway, this is too tangental to the point at hand - I tend to agree with Joe on this one, in that I want two isolated means of knowing the PO2 in the loop to be operational at the start-of-dive. One meter on one cord doesn't meet that requirement.

silent running · 12th December 2005, 22:55

Quote: (Originally Posted by jradomski)

I'm not disagreeing with levels of failure.. when you dove with just the secondary, did you check all 3 cells everytime you checked your display, if not its no better than just having one cell.. since you have no way of knowing without checking that the one cell is correct..

There is still the possiblity of banging the secondary against something underwater.. (we all have goten surprised by surge at one time or another)

There is a chance of entanglement.. I knwo I wouldn;t hesitate cutting my cable to one of my handsets If I had to.. with 1 operational it now makes it a difficult choice.. This one think I will miss on the new HH, my old one had removable handsets, and ONCE I got entangled and couldn;t see where it got hooked.. I just said to myself screw it,unhooked the cable and aborted the dive on the remaining handset... If I was down to one I would have had to find how and where it got entangled..

Hi Joe, yes I did scroll through all three sensors, always do. I see your point about the handsets, but there is no easy way to unclip the Prism 2ndary anyway, other than cutting the wire. And other than your old HH, I don't think that any other manufacturer allows for the easy detachment of handsets underwater. One could also look at the problem you had as another argument for keeping the overall number of loose cables to a minimum. Having only 1 handset is 1 less entaglement possibility and another reason I don't like units with 2 handsets or additional plumbed in O2 sensors... -Andy

silent running · 12th December 2005, 23:07

Quote: (Originally Posted by Genesis)

I know we're off-topic here but the ramps are for trucks, which have pneumatically-operated brakes that DO NOT work like those in your car - they are completely different both in how they normally work and in their failure modes and effects.

A properly adjusted passenger car parking brake WILL stop a car going down a hill at 70mph. It will take quite a distance, but it will stop you; the parking brake is (if properly adjusted) quite capable of locking the rear wheels.

(Speaking as someone who has done more than a few "J" turns in his car over the years..... that maneuver REQUIRES a properly-working handbrake - and who HAS had to stop using the parking brake before (don't ask!))

Anyway, this is too tangental to the point at hand - I tend to agree with Joe on this one, in that I want two isolated means of knowing the PO2 in the loop to be operational at the start-of-dive. One meter on one cord doesn't meet that requirement.

Genesis, Joe, granted it wasn't the best example, but the situation I was refering to in a car was having an identical, duplicate brake pedal very near the primary, hence the CCR analogy to duplicate displays, which no car has. Should have been more specific. If that were the case, it would be easier to use than that 1/2 size one on my F250, all the way over on the left, which I have to raise my knee up very high and carefully to engage. Given the way most people drive, there are plenty of situations where total sudden loss of brake control due to a mechanical linkage failure might leave no time to react other than moving over an inch or 2 to a separate, equall redundant pedal. My fault for making things more complicated.-Andy

Mike · 13th December 2005, 01:02

I'm in the middle of resolving a problem on my Prism at the moment, so I guess this counts as an example.
On / Off reed switch is sticking on, noticed as I was about to get on a boat on sunday.
Decided to disable the switch (after chatting to another Prism diver) in the off position and dive on the secondary only. Dive was rec - 28m depth for 30 minutes bottom time.
Primary breathing supply - Prism with analog guage
Secondary breathing supply - OC bailout

I don't see what the big deal is - while everything's working I'll stay on the loop, if the secondary fails, or is giving readings I don't like, go semiclosed or bail to OC. I don't think there is a realistic chance of the secondary failing in a manner that I will not notice, so I do not see any increased RISK over diving a kiss. There may be an increased chance of having to bail out, but even that is debateable. (Really depends on whether you would continue to dive a kiss if one display failed and you had two opertational. If not, then in both the kiss case, and the Prism case, one failure ends the dive).

So - I did the dive, running MLV and checking one or three sensors as I saw fit throughout the dive. Good practice to run manually.

On the phone today, and SMI are send out a new switch, should get it in time to dive this weekend. If that was going to be an issue, I had two other offers of a replacement switch.

So for me;
I'd dive a Kiss with one display down, and two working
I'll dive the Prism with the Primary off, using the secondary only
I would not dive the Inspo on one handset as I'm not convinced that a problem on one handset could not affect the other
I don't know enough about a Meg to comment.

BTW - the car brake analogy is flawed
1.most modern cars run seperate hydrolic circuits front and rear - so have some redundancy built in.
2. I have raced cars (lotus 7, porsche 924/928 hybrid, formula Vee) with both cable and independant hydrolic handbrakes. They will not do shit to stop you in any timeframe that makes a difference, particularly in road rallies.
3. Being able to lock a set of wheels with a braking system is absolutely no indication that it will be able to stop you from 200 kmph. Being able to modulate pressure so you don't lock the wheels, and then bleed off a whole bunch of energy is a lot more difficult.

Off topic except to say that;
Racing my lotus I'm quite aware that one failure in a critical system (steering would be the worst) and it's going to be a bad day. Diving the Prism, even with the electronic off, I'm quite confident that I can easily survive a major component failure and make it home without stress.
Driving a car at speed, a 10 second failure to observe and react will be bad. Diving the rebreather, even manually, not paying attenting for a few minutes is not likely to have any effect.

I feel safer on the racetrack than driving on the road, and safer on the rebreather than on the track. (Racing is more fun though)

Mike

12th December 2005, 22:27	#31 (permalink)
*jradomski* Moderator Current Rebreather/s: Inspiration Classic Sport Kiss Optima rEvo Other CCR Other Rebreather/s: Inspiration Vision Evolution Megalodon Classic Kiss rEvo Other CCR Join Date: Mar 2005 Location: "Da" Bronx Posts: 3,113	Re: Quote: (Originally Posted by caveseeker7) Thanks for laying that out, Joe. The 3/3 setup is good to have, especially when it's all you got. The independent and separate electronic and analog combo of the PRISM and MK are my preference, that's probably the only thing where we differ. You prefer lots of features and options, I prefer simplicity. I was trying to figure out Why you thought I was attacking the PRISM.. I still don;t see it.. All I said is I wouldn;t dive with just a secondary... I never mentioned a specific unit.. The HH, MK15, Prism all use the term secondary.. Just one operational now effectively makes it a primary, without all the functions intended for a primary... __________________ Joe Radomski CCR Trimix Instructor Trainer ANDI Instructor Trainer Director #10 All posts are personal opinions and DO NOT reflect any affiliated agency unless specifically stated.
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12th December 2005, 22:29	#32 (permalink)
Genesis Bubbless Box of Death Current Rebreather/s: Home Build Other Rebreather/s: Home Build Join Date: Oct 2005 Location: Sunny Florida Posts: 1,453	Re: SMI Prism training Uh, there is an emergency pedal on every car I've been in (or an emergency lever.) Its called the parking brake, and while it only actuates two of the 4 wheel brakes (and the weakest two for stopping a moving vehicle at that) it WILL bring you to a stop and is on a completely-indepedant cable linkage from the service brake hydraulic circuit. Bad example
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12th December 2005, 22:29	#33 (permalink)
*jradomski* Moderator Current Rebreather/s: Inspiration Classic Sport Kiss Optima rEvo Other CCR Other Rebreather/s: Inspiration Vision Evolution Megalodon Classic Kiss rEvo Other CCR Join Date: Mar 2005 Location: "Da" Bronx Posts: 3,113	Re: SMI Prism training Quote: (Originally Posted by silent running) Hi Joe, about this redundancy thing, I think it's worth considering the ways in which things most likely fail. I don't know of any Prism 2ndrys failing underwater. Why? Because there is really nothing to go wrong, especially when the power is off. I do know of many, many Kiss displays flooding or getting wet enough to not work. I'm not saying that having 3 separate Kiss displays is a bad idea, obviously it works and is a necessary part of the design, which is overall, very safe. But I don't think the "1 display is 1 display" thing takes everything into account. Remember, there is only one brake pedal in your car, what if the mechanical linkage somehow came apart? You'd crash. And this does happen once in a great while. But not enough to have everybody demanding an emergency pedal be made part of the design. Everything carries risk, there are ones which are acceptable to most people and ones which are not. And of course reasonable people can disagree... -Andy When it comes to life support equipment underwater I tend to error on the side of caution.. There is always tomorrow to make a dive.. Inmy mind no dive has to be done today (unless you were going to rescue someone, the I would do whatever was necessary).. Genesis, You beat me to the "emergency" brake.. __________________ Joe Radomski CCR Trimix Instructor Trainer ANDI Instructor Trainer Director #10 All posts are personal opinions and DO NOT reflect any affiliated agency unless specifically stated. Last edited by jradomski : 12th December 2005 at 22:34.
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12th December 2005, 22:39	#34 (permalink)
silent running Mature mouth breather Current Rebreather/s: Prism Topaz Other Rebreather/s: Join Date: Jun 2005 Location: U.S.A. Brooklyn, New York Posts: 1,873	Re: SMI Prism training Quote: (Originally Posted by Genesis) Uh, there is an emergency pedal on every car I've been in (or an emergency lever.) Its called the parking brake, and while it only actuates two of the 4 wheel brakes (and the weakest two for stopping a moving vehicle at that) it WILL bring you to a stop and is on a completely-indepedant cable linkage from the service brake hydraulic circuit. Bad example Hi Genesis, I understand your point, but pulling the parking brake lever aint gonna do much when you're doing 70 mph down a hill. That's why they have those runaway vehicle ramps on highways here in the US. Not to mention that the average person would likely panic and freeze up and not even think of applying the parking brake...But I digress further... -Andy
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12th December 2005, 22:42	#35 (permalink)
*jradomski* Moderator Current Rebreather/s: Inspiration Classic Sport Kiss Optima rEvo Other CCR Other Rebreather/s: Inspiration Vision Evolution Megalodon Classic Kiss rEvo Other CCR Join Date: Mar 2005 Location: "Da" Bronx Posts: 3,113	Re: SMI Prism training Quote: (Originally Posted by silent running) Hi Joe, about this redundancy thing, I think it's worth considering the ways in which things most likely fail. I don't know of any Prism 2ndrys failing underwater. Why? Because there is really nothing to go wrong, especially when the power is off. I do know of many, many Kiss displays flooding or getting wet enough to not work. I'm not saying that having 3 separate Kiss displays is a bad idea, obviously it works and is a necessary part of the design, which is overall, very safe. But I don't think the "1 display is 1 display" thing takes everything into account. Remember, there is only one brake pedal in your car, what if the mechanical linkage somehow came apart? You'd crash. And this does happen once in a great while. But not enough to have everybody demanding an emergency pedal be made part of the design. Everything carries risk, there are ones which are acceptable to most people and ones which are not. And of course reasonable people can disagree... -Andy I'm not disagreeing with levels of failure.. when you dove with just the secondary, did you check all 3 cells everytime you checked your display, if not its no better than just having one cell.. since you have no way of knowing without checking that the one cell is correct.. There is still the possiblity of banging the secondary against something underwater.. (we all have goten surprised by surge at one time or another) There is a chance of entanglement.. I knwo I wouldn;t hesitate cutting my cable to one of my handsets If I had to.. with 1 operational it now makes it a difficult choice.. This one think I will miss on the new HH, my old one had removable handsets, and ONCE I got entangled and couldn;t see where it got hooked.. I just said to myself screw it,unhooked the cable and aborted the dive on the remaining handset... If I was down to one I would have had to find how and where it got entangled.. __________________ Joe Radomski CCR Trimix Instructor Trainer ANDI Instructor Trainer Director #10 All posts are personal opinions and DO NOT reflect any affiliated agency unless specifically stated.
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12th December 2005, 22:48	#36 (permalink)
Underwaterbear A Prismer in Megland Current Rebreather/s: Prism Topaz Other Rebreather/s: Join Date: May 2005 Location: Seattle, WA Posts: 198	Re: SMI Prism training Quote: (Originally Posted by caveseeker7) ...snip I agree that Rebreather users should have a 'save-the-dive' kit available, just as most divers do. SMI offers it for the PRISM, they'll provide advice individually as to what it should contain based on the diving profiles and locations. I don't know if anyone in Oz bothered to get one, including the importer. ...snip Well, actually we wound up with a whole unit as a spare parts rig and we needed it. As has been mentioned around here before...to be totally frank, the ten units shipped to Oz, in combination, had what I and others considered a very large number of problems ranging from minor assembly issues to major failures of components and to top it all off a very unusual software glitch that wasn't caught until way too late in my personal opinion. Despite all these problems all 9 users were able to dive their units after some canibalisation, repair, rebuilding. Put these problems down to the move to TN... yeah maybe (still should have caught the assembly and s/w glitches). Put them down to the other "issues" with the whole deal...probably a factor. Put the fact users were slow to pick up later issues down to an inexperienced instructor staright from his course...probably a factor. How big a deal was the fact we are 4 days by air freight from the factory? Not nearly as big a problem as the human factors involved. Bottom line: Not one commercial Rebreather manufacturer has anything like the support capacity of a major corporation, SMI are no different. The unit has it's idiosyncracies (they all do), but is a very well designed Rb that is a pleasure to dive...in the water it's easily the best I've tried. There are not many things you can do that will keep the unit out of the water...even my catastrophically smashed head could have been glued back together with epoxy and probably dived had it been more crucial for me to do so. Final note...carry a small range of common spares and at the end of the day there is hardly a spot on the planet Fed Ex can't get to. Cheers Andrew
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12th December 2005, 22:52	#37 (permalink)
Genesis Bubbless Box of Death Current Rebreather/s: Home Build Other Rebreather/s: Home Build Join Date: Oct 2005 Location: Sunny Florida Posts: 1,453	Re: SMI Prism training Quote: (Originally Posted by silent running) Hi Genesis, I understand your point, but pulling the parking brake lever aint gonna do much when you're doing 70 mph down a hill. That's why they have those runaway vehicle ramps on highways here in the US. Not to mention that the average person would likely panic and freeze up and not even think of applying the parking brake...But I digress further... -Andy I know we're off-topic here but the ramps are for trucks, which have pneumatically-operated brakes that DO NOT work like those in your car - they are completely different both in how they normally work and in their failure modes and effects. A properly adjusted passenger car parking brake WILL stop a car going down a hill at 70mph. It will take quite a distance, but it will stop you; the parking brake is (if properly adjusted) quite capable of locking the rear wheels. (Speaking as someone who has done more than a few "J" turns in his car over the years..... that maneuver REQUIRES a properly-working handbrake - and who HAS had to stop using the parking brake before (don't ask!)) Anyway, this is too tangental to the point at hand - I tend to agree with Joe on this one, in that I want two isolated means of knowing the PO2 in the loop to be operational at the start-of-dive. One meter on one cord doesn't meet that requirement.
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12th December 2005, 22:55	#38 (permalink)
silent running Mature mouth breather Current Rebreather/s: Prism Topaz Other Rebreather/s: Join Date: Jun 2005 Location: U.S.A. Brooklyn, New York Posts: 1,873	Re: SMI Prism training Quote: (Originally Posted by jradomski) I'm not disagreeing with levels of failure.. when you dove with just the secondary, did you check all 3 cells everytime you checked your display, if not its no better than just having one cell.. since you have no way of knowing without checking that the one cell is correct.. There is still the possiblity of banging the secondary against something underwater.. (we all have goten surprised by surge at one time or another) There is a chance of entanglement.. I knwo I wouldn;t hesitate cutting my cable to one of my handsets If I had to.. with 1 operational it now makes it a difficult choice.. This one think I will miss on the new HH, my old one had removable handsets, and ONCE I got entangled and couldn;t see where it got hooked.. I just said to myself screw it,unhooked the cable and aborted the dive on the remaining handset... If I was down to one I would have had to find how and where it got entangled.. Hi Joe, yes I did scroll through all three sensors, always do. I see your point about the handsets, but there is no easy way to unclip the Prism 2ndary anyway, other than cutting the wire. And other than your old HH, I don't think that any other manufacturer allows for the easy detachment of handsets underwater. One could also look at the problem you had as another argument for keeping the overall number of loose cables to a minimum. Having only 1 handset is 1 less entaglement possibility and another reason I don't like units with 2 handsets or additional plumbed in O2 sensors... -Andy
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12th December 2005, 23:07	#39 (permalink)
silent running Mature mouth breather Current Rebreather/s: Prism Topaz Other Rebreather/s: Join Date: Jun 2005 Location: U.S.A. Brooklyn, New York Posts: 1,873	Re: SMI Prism training Quote: (Originally Posted by Genesis) I know we're off-topic here but the ramps are for trucks, which have pneumatically-operated brakes that DO NOT work like those in your car - they are completely different both in how they normally work and in their failure modes and effects. A properly adjusted passenger car parking brake WILL stop a car going down a hill at 70mph. It will take quite a distance, but it will stop you; the parking brake is (if properly adjusted) quite capable of locking the rear wheels. (Speaking as someone who has done more than a few "J" turns in his car over the years..... that maneuver REQUIRES a properly-working handbrake - and who HAS had to stop using the parking brake before (don't ask!)) Anyway, this is too tangental to the point at hand - I tend to agree with Joe on this one, in that I want two isolated means of knowing the PO2 in the loop to be operational at the start-of-dive. One meter on one cord doesn't meet that requirement. Genesis, Joe, granted it wasn't the best example, but the situation I was refering to in a car was having an identical, duplicate brake pedal very near the primary, hence the CCR analogy to duplicate displays, which no car has. Should have been more specific. If that were the case, it would be easier to use than that 1/2 size one on my F250, all the way over on the left, which I have to raise my knee up very high and carefully to engage. Given the way most people drive, there are plenty of situations where total sudden loss of brake control due to a mechanical linkage failure might leave no time to react other than moving over an inch or 2 to a separate, equall redundant pedal. My fault for making things more complicated.-Andy
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13th December 2005, 01:02	#40 (permalink)
Mike Prism 'prentice Current Rebreather/s: Prism Topaz Other Rebreather/s: Inspiration Classic Evolution Join Date: Feb 2005 Location: Melbourne Posts: 332	Re: SMI Prism training I'm in the middle of resolving a problem on my Prism at the moment, so I guess this counts as an example. On / Off reed switch is sticking on, noticed as I was about to get on a boat on sunday. Decided to disable the switch (after chatting to another Prism diver) in the off position and dive on the secondary only. Dive was rec - 28m depth for 30 minutes bottom time. Primary breathing supply - Prism with analog guage Secondary breathing supply - OC bailout I don't see what the big deal is - while everything's working I'll stay on the loop, if the secondary fails, or is giving readings I don't like, go semiclosed or bail to OC. I don't think there is a realistic chance of the secondary failing in a manner that I will not notice, so I do not see any increased RISK over diving a kiss. There may be an increased chance of having to bail out, but even that is debateable. (Really depends on whether you would continue to dive a kiss if one display failed and you had two opertational. If not, then in both the kiss case, and the Prism case, one failure ends the dive). So - I did the dive, running MLV and checking one or three sensors as I saw fit throughout the dive. Good practice to run manually. On the phone today, and SMI are send out a new switch, should get it in time to dive this weekend. If that was going to be an issue, I had two other offers of a replacement switch. So for me; I'd dive a Kiss with one display down, and two working I'll dive the Prism with the Primary off, using the secondary only I would not dive the Inspo on one handset as I'm not convinced that a problem on one handset could not affect the other I don't know enough about a Meg to comment. BTW - the car brake analogy is flawed 1.most modern cars run seperate hydrolic circuits front and rear - so have some redundancy built in. 2. I have raced cars (lotus 7, porsche 924/928 hybrid, formula Vee) with both cable and independant hydrolic handbrakes. They will not do shit to stop you in any timeframe that makes a difference, particularly in road rallies. 3. Being able to lock a set of wheels with a braking system is absolutely no indication that it will be able to stop you from 200 kmph. Being able to modulate pressure so you don't lock the wheels, and then bleed off a whole bunch of energy is a lot more difficult. Off topic except to say that; Racing my lotus I'm quite aware that one failure in a critical system (steering would be the worst) and it's going to be a bad day. Diving the Prism, even with the electronic off, I'm quite confident that I can easily survive a major component failure and make it home without stress. Driving a car at speed, a 10 second failure to observe and react will be bad. Diving the rebreather, even manually, not paying attenting for a few minutes is not likely to have any effect. I feel safer on the racetrack than driving on the road, and safer on the rebreather than on the track. (Racing is more fun though) Mike __________________ Open ....... Closed Mind ........ Loop
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