Sentinel on-course report

Marvintpa · 11th May 2008, 23:22

There are an increasing number of these units in the wild now but I could find only a limited amount of information which disappointed me, so I’ll do what I can to add my two cents on the Sentinel as a total newbie to the unit in the event it might help someone else who was as curious about it as I. I’ll try to write each day of the course to get the immediate impressions rather than wait until the end and risk sugar coating something.

Day 1
Putting the unit together wasn’t hard, even the first time, but it didn’t leave me with the warm and fuzzies. It is a nice looking piece of kit, the machining is excellent, but some of it looks like it was designed by an engineer with too much spare time. One end of the scrubber canister is moved during the filling process, which just strikes me as weird (you fill it to a certain level then lift the canister which causes the bottom to drop slightly, then refill again). Once the canister is packed it’s spring loaded into a base and held in place with fixed clips. When the base is installed in the rebreather the clips disengage and the spring tension shoots the canister into the ‘breather and mates it into a triple seal towards the top. The only word I can think of for that is “contrived”, and it’s not intended as a compliment. Trying this at first it failed repeatedly to fire the canister into its destination correctly. We swapped parts between the two rebreathers just as a test and it worked (and worked each time since for the rest of the week), but the damage has been done and I’m afraid I don’t have much faith in this feature at the moment.

Both units have trouble with the secondary handset not turning off, ever. They’re supposed to turn off after 15 seconds. This is likely a very easy fix for the factory but the factory is several thousand miles away.

Not having a full backplate there isn’t much weight to the setup and fair amount of lead has to be added to dive in cold temperatures. For my fat ass and a lot of undies in a CF200 that means 22 lbs (the light weight is likely a bonus to warm water divers, however). Due to the curve of the counterlung bump at the top of the shoulder it looks like it’ll be tough to fit a normal backplate. The harness will be the first thing to go. Coming from a one-piece-webbing background this thing has too many parts and too little flexibility to me.

The wing seems quite good, rectangular with a decent amount of lift. Not sure why it has a pull dump on the back of the right shoulder, though, and I’ve already had that pull string snag on other gear so it will have to go since there’s no way I could reach that under water.

From the pictures posted on Rebreather World I thought the reg hoses were long, but I was wrong, they’re even longer than that. They are impressively large diameter, but foly huck are they ever long, I think if I hold them vertically they’ll be just about as tall as me (5’9”).

Day 2
In the water this thing breathes great. Granted, my frame of reference only includes what are perhaps the two worst breathing setups out there (RB80, my first love, and the KISS Classic) but this thing breathes really well in any orientation I tried it which was practically everything but a summersault. The ADV seemed to fire a little more when I rolled onto my left side for some reason, but there was no effect to WOB. Setpoint is held quite well. The handsets are much smaller than the VR3 bricks (not bashing, I have one of those, too). The handsets are complicated, but due to what you can monitor and change on the fly I guess they have to be. Can’t really comment on the trim because of all the weight I had to add and it not being in the places I’d prefer. This will be improved later and I’m sure the butt-heavy tendency I experienced can be lessened dramatically. My buddy, who’d had the body of his unit ahead of time, rigged some creative weighting and had outstanding trim.

Day 3
The hose for the BOV reg seems just a tad short which causes the BOV reg to pivot under the mouthpiece, which then causes it to be even farther in front of the mouthpiece which makes it harder to switch from closed to open circuit. Certainly not a big deal but in an emergency every fraction of a second could count. The rotating switch to change from closed to open circuit is scalloped on the sides, instead of being just straight, which also seems to make it harder to read the position of with thick gloves on.

The more I use it, tear it apart, and play with it the greater my fears of puncturing the counterlung. The material is decently thick and looks strong, but has a tendency to extrude a little from time to time at the top of the case, and there are a couple of metal hooks used for holding down the counterlung mounting ring that concern me due to their potential puncturing skills.

The sliders on the manual injection blocks over both shoulders are very easy to access and actuate, seems like a great idea and execution.

The sliding “foot” continues to puzzle me a little. It’s too thin/flexible and small to be a stand like a Narced at 90 CK stand (which is great). It’s purpose is likely more to protect the first stages and possibly act as a strain relief for the back, which it seems to do admirably, but it could be so much more.

Had a bit of an issue with the dil nearly constantly feeding gas and the OPV venting almost the same amount. Turns out I hadn’t turned the BOV all the way back to the loop following a drill, this took awhile to troubleshoot. I believe it was caused by the way you can get a thick glove pinched between the BOV switch and the slightly rotated BOV reg, which can make it feel like you’ve turned it all the way. Or it could just have been caused by me being an idiot.

Day 4
So that’s what a caustic cocktail tastes like. As a beverage it even makes Pepsi taste good. Sixty-five minutes into the first dive of the day I aspirated a decent amount of caustic, was able to puke it out and make a less-than-pretty ascent on bailout, which I exhausted at speed as I uncontrollably attempted to cough up every lung I have, then borrowed someone else’s (bailout, not lungs) to finish the trip to the surface. Turns out there’d been a small cut in the counterlung. I’d had a slight leak during the negative test, checked a few things and did it again and it held quite well (there appears to be a small leak in the BOV which causes you to have to put the base of your thumb over the mouthpiece to perform the negative test – this concerns me because 1. there is a leak I don’t believe should be there and 2. a perfect negative is almost impossible since my thumb doesn’t seal all that well). In the water there was a very tiny sound I wasn’t familiar with that would occur only after I’d inhale – I had no idea what it was and I made the decision to continue, which turned out to be the wrong one (entirely my fault). Learned that one the hard way.

After tearing the unit down we eventually found the cut, about a half-inch long about an inch and a half away from the ring that attaches the counterlung to the rebreather – too far from the edges for it to have been cut by extruding, but I couldn’t definitively say what it had been cut by. There were actually two cuts roughly the same distance from the attaching ring roughly 90 degrees apart, both dead straight and about the same length, only one went all the way through the material. I was elated to have a definitive cause of the caustic so kept diving feeling we’d resolved the issue and I knew what to look out for on that one.

Day 5
After yesterday’s adventure today was practically boring. Unit performed perfectly and all was well with the world again aside from a sore throat and a new sense of respect for pre-dive checks and tiny sounds I’ve never heard before.

Much like the ‘Boris when it first came out there were some issues that needed to be addressed, and were. This appears to be repeating with the Sentinel. I’ve heard about the things CCRB is doing to enhance the units, and it appears there’s nothing I’ve mentioned here they’re not already aware of and working on so none of it will be news aside from perhaps the incorrect firing of the canister into the head which I’m told didn’t occur during the Red Sea event, so guess I’m just special.

Overall I like the unit and I’m glad I bought one. It’s not perfect but I’m unaware of any rebreathers that started perfect as soon as they were introduced – a rapid evolution immediately after launch appears to pretty much be the norm.

I’ll continue to update this thread should any of these issues get resolved. It could be awhile as my personal unit is not expected to arrive for a few weeks yet (I’m told one of the reasons for the delay is they’re working on a new counterlung design), I was using a much-appreciated loaner for the course.

These are just my simple observations. As usual with anything on the internet, they're likely worth whatcha paid for them.

mountain diver · 12th May 2008, 01:14

Thanks for the report, look forward to the updates.

all the best.

***Decodiver*** · 12th May 2008, 10:18

Regarding the weight issue, I have asked John Perrin at Kent Tooling to make a 1.8 kilo weight for the backplate, that is an identical of the lower half of the original plate, it lays over your original plate and has the bolts recessed into it.

John makes the Sentinel backplate for CCR Ltd.

I used it for the first time this weekend and took 2 kilos off my unit.

I now only need 2 kilos with a Golem heated vest cannister and a salvo torch wearing a Fourth Element arctic top, DUI Fleece jumpsuit and TLS 350, now that summer is here!

If you are interested, John is available on here as KENT TOOLING.

Did you repair the counterlung or replace it? If you repaired it what method did you use?

Cheers,

Dave Cooper.

Marvintpa · 12th May 2008, 13:09

That backplate certainly sounds like a step in the right direction. A couple of the guys here have already ordered them, or something like it. I'm wondering if something heavier might be possible.

We used Aquaseal, Cotol and a bike patch, then remembered we had a spare counterlung from another unit so I dived that and our patch didn't get tested in the water.

deedee · 12th May 2008, 14:22

Great report .. I look forward to all the dry glove tips you can share.
My turn is aproaching fast

Darek

KENT TOOLING · 12th May 2008, 17:01

Quote: (Originally Posted by Marvintpa)

That backplate certainly sounds like a step in the right direction. A couple of the guys here have already ordered them, or something like it. I'm wondering if something heavier might be possible.

How much heavier do you require as any thing is possible as long as i have the machine capacity to form it, and will the Sentinel take a much heavier plate

If you require any further infomation you can contact me on the numbers below

John

vtach67 · 14th May 2008, 15:50

I was Tom's buddy for the course and he summarized the issues we had quite well. I really don't know what more that I could add that he did not already cover. I have received forwarded correspondence from Kevin Gurr and it is apparent that they are addressing the issues, explaining rationale behind decisions and also open to suggestion. I am pleased with that.

I can say that watching the circumstances surrounding the cocktail were quite sobering. Tom is a very skilled diver and his ability to deal with the situation without panic really demonstrated how necessary it is to be proficient in your skills. I fully agree with his sentiment regarding solid positive and negative checks along with the importance of carrying bailout gas and routine bailout drills.

I am also happy with the Sentinel, it is a quality built unit and I feel has a lot of potential. I found the biggest drawback for me through the week (outside of the bouyancy learning curve) was the mouthpiece. After 4 days of class the inside of my upper lip was like hamburger. Tom was gracious to enough to offer me a Sea Cure moldable mouthpiece that he had. After installing that, life was good again.

I am really looking forward to see what CCRB comes up with for a caseless option. I really like a more modular arrangement and not a big fan of the case. I am hoping that it will be something more friendly to a common BP/W arrangement.

11th May 2008, 23:22	#1 (permalink)
Marvintpa Bad knees, matching brain Current Rebreather/s: Classic Kiss Other Rebreather/s: Join Date: Mar 2005 Location: Ontario, Canada Posts: 233	Sentinel on-course report There are an increasing number of these units in the wild now but I could find only a limited amount of information which disappointed me, so I’ll do what I can to add my two cents on the Sentinel as a total newbie to the unit in the event it might help someone else who was as curious about it as I. I’ll try to write each day of the course to get the immediate impressions rather than wait until the end and risk sugar coating something. Day 1 Putting the unit together wasn’t hard, even the first time, but it didn’t leave me with the warm and fuzzies. It is a nice looking piece of kit, the machining is excellent, but some of it looks like it was designed by an engineer with too much spare time. One end of the scrubber canister is moved during the filling process, which just strikes me as weird (you fill it to a certain level then lift the canister which causes the bottom to drop slightly, then refill again). Once the canister is packed it’s spring loaded into a base and held in place with fixed clips. When the base is installed in the rebreather the clips disengage and the spring tension shoots the canister into the ‘breather and mates it into a triple seal towards the top. The only word I can think of for that is “contrived”, and it’s not intended as a compliment. Trying this at first it failed repeatedly to fire the canister into its destination correctly. We swapped parts between the two rebreathers just as a test and it worked (and worked each time since for the rest of the week), but the damage has been done and I’m afraid I don’t have much faith in this feature at the moment. Both units have trouble with the secondary handset not turning off, ever. They’re supposed to turn off after 15 seconds. This is likely a very easy fix for the factory but the factory is several thousand miles away. Not having a full backplate there isn’t much weight to the setup and fair amount of lead has to be added to dive in cold temperatures. For my fat ass and a lot of undies in a CF200 that means 22 lbs (the light weight is likely a bonus to warm water divers, however). Due to the curve of the counterlung bump at the top of the shoulder it looks like it’ll be tough to fit a normal backplate. The harness will be the first thing to go. Coming from a one-piece-webbing background this thing has too many parts and too little flexibility to me. The wing seems quite good, rectangular with a decent amount of lift. Not sure why it has a pull dump on the back of the right shoulder, though, and I’ve already had that pull string snag on other gear so it will have to go since there’s no way I could reach that under water. From the pictures posted on Rebreather World I thought the reg hoses were long, but I was wrong, they’re even longer than that. They are impressively large diameter, but foly huck are they ever long, I think if I hold them vertically they’ll be just about as tall as me (5’9”). Day 2 In the water this thing breathes great. Granted, my frame of reference only includes what are perhaps the two worst breathing setups out there (RB80, my first love, and the KISS Classic) but this thing breathes really well in any orientation I tried it which was practically everything but a summersault. The ADV seemed to fire a little more when I rolled onto my left side for some reason, but there was no effect to WOB. Setpoint is held quite well. The handsets are much smaller than the VR3 bricks (not bashing, I have one of those, too). The handsets are complicated, but due to what you can monitor and change on the fly I guess they have to be. Can’t really comment on the trim because of all the weight I had to add and it not being in the places I’d prefer. This will be improved later and I’m sure the butt-heavy tendency I experienced can be lessened dramatically. My buddy, who’d had the body of his unit ahead of time, rigged some creative weighting and had outstanding trim. Day 3 The hose for the BOV reg seems just a tad short which causes the BOV reg to pivot under the mouthpiece, which then causes it to be even farther in front of the mouthpiece which makes it harder to switch from closed to open circuit. Certainly not a big deal but in an emergency every fraction of a second could count. The rotating switch to change from closed to open circuit is scalloped on the sides, instead of being just straight, which also seems to make it harder to read the position of with thick gloves on. The more I use it, tear it apart, and play with it the greater my fears of puncturing the counterlung. The material is decently thick and looks strong, but has a tendency to extrude a little from time to time at the top of the case, and there are a couple of metal hooks used for holding down the counterlung mounting ring that concern me due to their potential puncturing skills. The sliders on the manual injection blocks over both shoulders are very easy to access and actuate, seems like a great idea and execution. The sliding “foot” continues to puzzle me a little. It’s too thin/flexible and small to be a stand like a Narced at 90 CK stand (which is great). It’s purpose is likely more to protect the first stages and possibly act as a strain relief for the back, which it seems to do admirably, but it could be so much more. Had a bit of an issue with the dil nearly constantly feeding gas and the OPV venting almost the same amount. Turns out I hadn’t turned the BOV all the way back to the loop following a drill, this took awhile to troubleshoot. I believe it was caused by the way you can get a thick glove pinched between the BOV switch and the slightly rotated BOV reg, which can make it feel like you’ve turned it all the way. Or it could just have been caused by me being an idiot. Day 4 So that’s what a caustic cocktail tastes like. As a beverage it even makes Pepsi taste good. Sixty-five minutes into the first dive of the day I aspirated a decent amount of caustic, was able to puke it out and make a less-than-pretty ascent on bailout, which I exhausted at speed as I uncontrollably attempted to cough up every lung I have, then borrowed someone else’s (bailout, not lungs) to finish the trip to the surface. Turns out there’d been a small cut in the counterlung. I’d had a slight leak during the negative test, checked a few things and did it again and it held quite well (there appears to be a small leak in the BOV which causes you to have to put the base of your thumb over the mouthpiece to perform the negative test – this concerns me because 1. there is a leak I don’t believe should be there and 2. a perfect negative is almost impossible since my thumb doesn’t seal all that well). In the water there was a very tiny sound I wasn’t familiar with that would occur only after I’d inhale – I had no idea what it was and I made the decision to continue, which turned out to be the wrong one (entirely my fault). Learned that one the hard way. After tearing the unit down we eventually found the cut, about a half-inch long about an inch and a half away from the ring that attaches the counterlung to the rebreather – too far from the edges for it to have been cut by extruding, but I couldn’t definitively say what it had been cut by. There were actually two cuts roughly the same distance from the attaching ring roughly 90 degrees apart, both dead straight and about the same length, only one went all the way through the material. I was elated to have a definitive cause of the caustic so kept diving feeling we’d resolved the issue and I knew what to look out for on that one. Day 5 After yesterday’s adventure today was practically boring. Unit performed perfectly and all was well with the world again aside from a sore throat and a new sense of respect for pre-dive checks and tiny sounds I’ve never heard before. Much like the ‘Boris when it first came out there were some issues that needed to be addressed, and were. This appears to be repeating with the Sentinel. I’ve heard about the things CCRB is doing to enhance the units, and it appears there’s nothing I’ve mentioned here they’re not already aware of and working on so none of it will be news aside from perhaps the incorrect firing of the canister into the head which I’m told didn’t occur during the Red Sea event, so guess I’m just special. Overall I like the unit and I’m glad I bought one. It’s not perfect but I’m unaware of any rebreathers that started perfect as soon as they were introduced – a rapid evolution immediately after launch appears to pretty much be the norm. I’ll continue to update this thread should any of these issues get resolved. It could be awhile as my personal unit is not expected to arrive for a few weeks yet (I’m told one of the reasons for the delay is they’re working on a new counterlung design), I was using a much-appreciated loaner for the course. These are just my simple observations. As usual with anything on the internet, they're likely worth whatcha paid for them. Last edited by Marvintpa : 11th May 2008 at 23:31.
(Offline)

12th May 2008, 01:14	#2 (permalink)
mountain diver Silent Lucidity Current Rebreather/s: Megalodon Other Rebreather/s: Join Date: Mar 2006 Location: edmonton, ab. Posts: 175	Re: Sentinel on-course report Thanks for the report, look forward to the updates. all the best.
(Offline)

12th May 2008, 10:18	#3 (permalink)
*Decodiver* Administrator Current Rebreather/s: Megalodon Ouroboros rEvo Other CCR Other Rebreather/s: Inspiration Classic Inspiration Vision Evolution Sport Kiss Classic Kiss rEvo Other CCR Join Date: Jan 2005 Location: Geneva Posts: 2,168	Re: Sentinel on-course report Regarding the weight issue, I have asked John Perrin at Kent Tooling to make a 1.8 kilo weight for the backplate, that is an identical of the lower half of the original plate, it lays over your original plate and has the bolts recessed into it. John makes the Sentinel backplate for CCR Ltd. I used it for the first time this weekend and took 2 kilos off my unit. I now only need 2 kilos with a Golem heated vest cannister and a salvo torch wearing a Fourth Element arctic top, DUI Fleece jumpsuit and TLS 350, now that summer is here! If you are interested, John is available on here as KENT TOOLING. Did you repair the counterlung or replace it? If you repaired it what method did you use? Cheers, Dave Cooper. __________________ CCR/OC Trimix Instructor Trainer CCR Training to Mixed Gas in Switzerland, France, UK & Germany on Megalodon/COPIS-Megalodon/KISS/Sport KISS/Ouroboros/rEvo/Inspiration/Evolution/Sentinel www.zerogravitydiving.com Rebreather World Terms & Conditions
(Offline)

12th May 2008, 13:09	#4 (permalink)
Marvintpa Bad knees, matching brain Current Rebreather/s: Classic Kiss Other Rebreather/s: Join Date: Mar 2005 Location: Ontario, Canada Posts: 233	Re: Sentinel on-course report That backplate certainly sounds like a step in the right direction. A couple of the guys here have already ordered them, or something like it. I'm wondering if something heavier might be possible. We used Aquaseal, Cotol and a bike patch, then remembered we had a spare counterlung from another unit so I dived that and our patch didn't get tested in the water.
(Offline)

12th May 2008, 14:22	#5 (permalink)
deedee New Member Current Rebreather/s: Other CCR Other Rebreather/s: Other CCR Join Date: Jan 2006 Location: Ontario Posts: 7	Re: Sentinel on-course report Great report .. I look forward to all the dry glove tips you can share. My turn is aproaching fast Darek
(Offline)

12th May 2008, 17:01	#6 (permalink)
KENT TOOLING New Member Current Rebreather/s: Inspiration Classic Other Rebreather/s: Join Date: Aug 2005 Location: UK Posts: 50	Re: Sentinel on-course report Quote: (Originally Posted by Marvintpa) That backplate certainly sounds like a step in the right direction. A couple of the guys here have already ordered them, or something like it. I'm wondering if something heavier might be possible. How much heavier do you require as any thing is possible as long as i have the machine capacity to form it, and will the Sentinel take a much heavier plate If you require any further infomation you can contact me on the numbers below John __________________ John Perrin +44 01227 700015 (Technical Director) KENT TOOLING (Diving Products) www.divingproducts.co.uk Fire & Smoke Damper Manufactures +44 01227 700015 www.tri-prodanpers.co.uk Last edited by Decodiver : 12th May 2008 at 17:28. Reason: Format quote
(Offline)

14th May 2008, 15:50	#7 (permalink)
vtach67 New Member Current Rebreather/s: Other CCR Other Rebreather/s: Other CCR Join Date: Oct 2007 Location: Wisconsin Posts: 9	Re: Sentinel on-course report I was Tom's buddy for the course and he summarized the issues we had quite well. I really don't know what more that I could add that he did not already cover. I have received forwarded correspondence from Kevin Gurr and it is apparent that they are addressing the issues, explaining rationale behind decisions and also open to suggestion. I am pleased with that. I can say that watching the circumstances surrounding the cocktail were quite sobering. Tom is a very skilled diver and his ability to deal with the situation without panic really demonstrated how necessary it is to be proficient in your skills. I fully agree with his sentiment regarding solid positive and negative checks along with the importance of carrying bailout gas and routine bailout drills. I am also happy with the Sentinel, it is a quality built unit and I feel has a lot of potential. I found the biggest drawback for me through the week (outside of the bouyancy learning curve) was the mouthpiece. After 4 days of class the inside of my upper lip was like hamburger. Tom was gracious to enough to offer me a Sea Cure moldable mouthpiece that he had. After installing that, life was good again. I am really looking forward to see what CCRB comes up with for a caseless option. I really like a more modular arrangement and not a big fan of the case. I am hoping that it will be something more friendly to a common BP/W arrangement.
(Online)

Thread Tools
Show Printable Version Email this Page
Display Modes
Linear Mode Switch to Hybrid Mode Switch to Threaded Mode