Cavediving related query.

solocavediver · 2nd November 2006, 14:04

Hi,

first of all immense congratulations on the amount and depth of thought that have gone into the Open Rev project.

One question. I read that if the diver attempts to dive the Open Rev without due process, it tries to dissuade him with audible warnings, making it difficult but not impossible to breathe off it, and also by forcibly inflating the counterlungs. As a cavediver I sympathise with this last but I have my reservations - on open circuit I have noticed how little of an air leak is necessary to paste the cave "diver" to the cave ceiling, and if this feature turned itself on by accident in mid-dive (rather than at the start) there might be serious trouble (it wouldn't be necessary to be at deco depths for the trouble to be serious). No doubt jumps to random bits of code are much less frequent with this design than with - erm - other designs, but still, for me it would be a niggle to think about... I would be looking for the manual override valve before anything else got done - even filling the scrubber !!

Cheers,

Charles Read.

AD_ward9 · 17th November 2006, 12:47

Quote: (Originally Posted by solocavediver)

Hi,

first of all immense congratulations on the amount and depth of thought that have gone into the Open Rev project.

One question. I read that if the diver attempts to dive the Open Rev without due process, it tries to dissuade him with audible warnings, making it difficult but not impossible to breathe off it, and also by forcibly inflating the counterlungs. As a cavediver I sympathise with this last but I have my reservations - on open circuit I have noticed how little of an air leak is necessary to paste the cave "diver" to the cave ceiling, and if this feature turned itself on by accident in mid-dive (rather than at the start) there might be serious trouble (it wouldn't be necessary to be at deco depths for the trouble to be serious). No doubt jumps to random bits of code are much less frequent with this design than with - erm - other designs, but still, for me it would be a niggle to think about... I would be looking for the manual override valve before anything else got done - even filling the scrubber !!

Cheers,

Charles Read.

Thanks for the input.

We had some less than positive feedback testing this feature. Now it turns off only if the loop is not breathable, and on the surface. We deal with the issues of running trimix in an air only unit differently (not allowing the profile to be downloaded normally, advising the diver to abort continuously etc).

It never inflates the lungs automatically, except on cal, which can only happen on the surface with no-one breathing on the loop and the handsets must be dry.

There is no code to jump to that causes this "feature" to run accidentally. If the microcontroller tries doing it, due to say an internal glitch causing the program counter to skip, then the FPGA overrides it and keeps control.

Cheers,

Alex

divetheworld · 17th November 2006, 13:09

Quote: (Originally Posted by solocavediver)

Hi,

first of all immense congratulations on the amount and depth of thought that have gone into the Open Rev project.

One question. I read that if the diver attempts to dive the Open Rev without due process, it tries to dissuade him with audible warnings, making it difficult but not impossible to breathe off it, and also by forcibly inflating the counterlungs. As a cavediver I sympathise with this last but I have my reservations - on open circuit I have noticed how little of an air leak is necessary to paste the cave "diver" to the cave ceiling, and if this feature turned itself on by accident in mid-dive (rather than at the start) there might be serious trouble (it wouldn't be necessary to be at deco depths for the trouble to be serious). No doubt jumps to random bits of code are much less frequent with this design than with - erm - other designs, but still, for me it would be a niggle to think about... I would be looking for the manual override valve before anything else got done - even filling the scrubber !!

Cheers,

Charles Read.

Dont worry, Alex promised from the onset that there would always be an "expedition" class model available without any of the control-freak electrickery enabled.
If thats still the case then I'm sure the OR will stil be on your list when it becomes available.

B

**PhilSiswick** · 17th November 2006, 14:14

Quote: (Originally Posted by divetheworld)

Dont worry, Alex promised from the onset that there would always be an "expedition" class model available without any of the control-freak electrickery enabled.
If thats still the case then I'm sure the OR will stil be on your list when it becomes available.

B

Doesn't that go against the point of the OR? A bit like switching off traction control on your car?

Cheers,

AD_ward9 · 17th November 2006, 15:36

Quote: (Originally Posted by PhilSiswick)

Doesn't that go against the point of the OR? A bit like switching off traction control on your car?

Cheers,

Nothing is taken off. Just the limits are increased.

Taking things off just means risks are no longer managed. There is no reason to do that, ever.

Alex

solocavediver · 7th December 2006, 09:48

Thanks for the info. I find it rather impressive that if I think up a fairly obscure question about the OR, Alex has obviously already thought about it....

Cheers,

Charles.

AD_ward9 · 8th December 2006, 03:18

Quote: (Originally Posted by solocavediver)

Thanks for the info. I find it rather impressive that if I think up a fairly obscure question about the OR, Alex has obviously already thought about it.....

Charles,
Thanks for your confidence, but it is the things we do not know that bite, and there are a lot of little detailed things nibbling away at the moment. We need to post more detail so people can open up the cans in exploring specific issues themselves.

To do this, we need to clean up the documentation. At the moment, we realise it is difficult for people to trace through it all easily. A good example of this is the gallery, where there are no subdivisions to distinguish each revision, so it is hard to tell what goes where.

Over the New Year break, there is a pile of detailed test results (Design Verification) reports I need to post, including the other FMECA documents, and full project technical documentation.

Cheers,

Alex

**PhilSiswick** · 8th December 2006, 10:43

Quote: (Originally Posted by AD_ward9)

Nothing is taken off. Just the limits are increased.

Taking things off just means risks are no longer managed. There is no reason to do that, ever.

Alex

Alex,

Sorry, I missed this response at the time. That approach makes a lot more sense.

Cheers,

2nd November 2006, 14:04	#1 (permalink)
solocavediver New Member Current Rebreather/s: Other CCR Home Build Other Rebreather/s: Other CCR Home Build Join Date: Apr 2006 Location: Leeds UK Posts: 106	Cavediving related query. Hi, first of all immense congratulations on the amount and depth of thought that have gone into the Open Rev project. One question. I read that if the diver attempts to dive the Open Rev without due process, it tries to dissuade him with audible warnings, making it difficult but not impossible to breathe off it, and also by forcibly inflating the counterlungs. As a cavediver I sympathise with this last but I have my reservations - on open circuit I have noticed how little of an air leak is necessary to paste the cave "diver" to the cave ceiling, and if this feature turned itself on by accident in mid-dive (rather than at the start) there might be serious trouble (it wouldn't be necessary to be at deco depths for the trouble to be serious). No doubt jumps to random bits of code are much less frequent with this design than with - erm - other designs, but still, for me it would be a niggle to think about... I would be looking for the manual override valve before anything else got done - even filling the scrubber !! Cheers, Charles Read.
(Offline)

17th November 2006, 12:47	#2 (permalink)
AD_ward9 So much more to learn Current Rebreather/s: Other CCR Other Rebreather/s: Other CCR Join Date: Jun 2005 Location: Scotland Posts: 1,853	Re: Cavediving related query. Quote: (Originally Posted by solocavediver) Hi, first of all immense congratulations on the amount and depth of thought that have gone into the Open Rev project. One question. I read that if the diver attempts to dive the Open Rev without due process, it tries to dissuade him with audible warnings, making it difficult but not impossible to breathe off it, and also by forcibly inflating the counterlungs. As a cavediver I sympathise with this last but I have my reservations - on open circuit I have noticed how little of an air leak is necessary to paste the cave "diver" to the cave ceiling, and if this feature turned itself on by accident in mid-dive (rather than at the start) there might be serious trouble (it wouldn't be necessary to be at deco depths for the trouble to be serious). No doubt jumps to random bits of code are much less frequent with this design than with - erm - other designs, but still, for me it would be a niggle to think about... I would be looking for the manual override valve before anything else got done - even filling the scrubber !! Cheers, Charles Read. Thanks for the input. We had some less than positive feedback testing this feature. Now it turns off only if the loop is not breathable, and on the surface. We deal with the issues of running trimix in an air only unit differently (not allowing the profile to be downloaded normally, advising the diver to abort continuously etc). It never inflates the lungs automatically, except on cal, which can only happen on the surface with no-one breathing on the loop and the handsets must be dry. There is no code to jump to that causes this "feature" to run accidentally. If the microcontroller tries doing it, due to say an internal glitch causing the program counter to skip, then the FPGA overrides it and keeps control. Cheers, Alex
(Offline)

17th November 2006, 13:09	#3 (permalink)
divetheworld Dive porn pimp Current Rebreather/s: Inspiration Classic Other CCR Other Rebreather/s: Not Bought Yet Inspiration Classic Inspiration Vision Classic Kiss Other CCR Join Date: Mar 2005 Location: Leeds, England Posts: 1,585	Re: Cavediving related query. Quote: (Originally Posted by solocavediver) Hi, first of all immense congratulations on the amount and depth of thought that have gone into the Open Rev project. One question. I read that if the diver attempts to dive the Open Rev without due process, it tries to dissuade him with audible warnings, making it difficult but not impossible to breathe off it, and also by forcibly inflating the counterlungs. As a cavediver I sympathise with this last but I have my reservations - on open circuit I have noticed how little of an air leak is necessary to paste the cave "diver" to the cave ceiling, and if this feature turned itself on by accident in mid-dive (rather than at the start) there might be serious trouble (it wouldn't be necessary to be at deco depths for the trouble to be serious). No doubt jumps to random bits of code are much less frequent with this design than with - erm - other designs, but still, for me it would be a niggle to think about... I would be looking for the manual override valve before anything else got done - even filling the scrubber !! Cheers, Charles Read. Dont worry, Alex promised from the onset that there would always be an "expedition" class model available without any of the control-freak electrickery enabled. If thats still the case then I'm sure the OR will stil be on your list when it becomes available. B __________________ Attitude and self praise is no reccomendation. Dont try to be a great man, just be a man and let history be the judge of you. CHECK OUT OUR INTERWEBS FOR CUSTOM REBREATHER UPGRADES *WWW.NARKEDAT90.CO.UK* *http://www.grpservices.com/pursuit/* Supporting Shearwater Research Products in Europe
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17th November 2006, 14:14	#4 (permalink)
PhilSiswick Phil Siswick, Tango Current Rebreather/s: Evolution Other Rebreather/s: Inspiration Vision Join Date: Apr 2006 Location: Oxford, UK Posts: 988	Re: Cavediving related query. Quote: (Originally Posted by divetheworld) Dont worry, Alex promised from the onset that there would always be an "expedition" class model available without any of the control-freak electrickery enabled. If thats still the case then I'm sure the OR will stil be on your list when it becomes available. B Doesn't that go against the point of the OR? A bit like switching off traction control on your car? Cheers, __________________ Phil (WSKD 0001) I have always felt that the dive I am on is not nearly important as the dives I plan to be on the rest of my life. Tom Rose, 2007 The person who gets the farthest is generally the one who is willing to do and dare. The sure thing boat never gets far from shore. Charles A. Lindbergh www.hugsac.org.uk
(Online)

17th November 2006, 15:36	#5 (permalink)
AD_ward9 So much more to learn Current Rebreather/s: Other CCR Other Rebreather/s: Other CCR Join Date: Jun 2005 Location: Scotland Posts: 1,853	Re: Cavediving related query. Quote: (Originally Posted by PhilSiswick) Doesn't that go against the point of the OR? A bit like switching off traction control on your car? Cheers, Nothing is taken off. Just the limits are increased. Taking things off just means risks are no longer managed. There is no reason to do that, ever. Alex
(Offline)

7th December 2006, 09:48	#6 (permalink)
solocavediver New Member Current Rebreather/s: Other CCR Home Build Other Rebreather/s: Other CCR Home Build Join Date: Apr 2006 Location: Leeds UK Posts: 106	Re: Cavediving related query. Thanks for the info. I find it rather impressive that if I think up a fairly obscure question about the OR, Alex has obviously already thought about it.... Cheers, Charles.
(Offline)

8th December 2006, 03:18	#7 (permalink)
AD_ward9 So much more to learn Current Rebreather/s: Other CCR Other Rebreather/s: Other CCR Join Date: Jun 2005 Location: Scotland Posts: 1,853	Re: Cavediving related query. Quote: (Originally Posted by solocavediver) Thanks for the info. I find it rather impressive that if I think up a fairly obscure question about the OR, Alex has obviously already thought about it..... Charles, Thanks for your confidence, but it is the things we do not know that bite, and there are a lot of little detailed things nibbling away at the moment. We need to post more detail so people can open up the cans in exploring specific issues themselves. To do this, we need to clean up the documentation. At the moment, we realise it is difficult for people to trace through it all easily. A good example of this is the gallery, where there are no subdivisions to distinguish each revision, so it is hard to tell what goes where. Over the New Year break, there is a pile of detailed test results (Design Verification) reports I need to post, including the other FMECA documents, and full project technical documentation. Cheers, Alex
(Offline)

8th December 2006, 10:43	#8 (permalink)
PhilSiswick Phil Siswick, Tango Current Rebreather/s: Evolution Other Rebreather/s: Inspiration Vision Join Date: Apr 2006 Location: Oxford, UK Posts: 988	Re: Cavediving related query. Quote: (Originally Posted by AD_ward9) Nothing is taken off. Just the limits are increased. Taking things off just means risks are no longer managed. There is no reason to do that, ever. Alex Alex, Sorry, I missed this response at the time. That approach makes a lot more sense. Cheers, __________________ Phil (WSKD 0001) I have always felt that the dive I am on is not nearly important as the dives I plan to be on the rest of my life. Tom Rose, 2007 The person who gets the farthest is generally the one who is willing to do and dare. The sure thing boat never gets far from shore. Charles A. Lindbergh www.hugsac.org.uk
(Online)

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