Comprehensive list of all accidents

Dave Sutton

Because that's what PR asked to have tested and because it's easier data to manipulate for sales purposes? . Call me a skeptic. The tests were not done to NEDU's protocols because it was a contract test of a commercial item and was not intended to qualify the unit for the USN to consider. You can slice and dice the PR from SM all you like, but the Navy never had any serious interest in the Prism, and anyone who's been around EDU knows it. To think that the Navy would ever consider anything with the build "quality" of the Prism as built by SM is absolutely laughable. SM Quality control? Don't make me laugh.

I'll be interested to see how it does test out if Alex can find a working one to try out, but in the end "who cares" as it's an out of production unit and the "Hollis" version is just vaporware for now. It would be a different unit in any case and would test differently. Speaking of Oceanic, I wonder how the Phibian will test?

BTW, the USN SDV mission has no requirement for a long swim. It's a seated position in the vehicle like sitting in a fully faired motorcycle. Upright would be the test point of interest.



Dave

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silent running

Lord please forgive me for taking the bait...

What exactly are you suggesting Dave? That SMI paid NEDU to have the Prism tested and then told them how to do it, or just conned an NEDU test engineer into doing it a certain way to suit SMI's needs? Or are you suggesting that the USN has the time, manpower and resources available to devote to 3 years of manned and un-manned testing just to humor Peter Readey? Are you saying that the NEDU documents posted on the SMI website stating the purpose of the tests are fraudulent or maybe just some sort of cover for a back door deal between NEDU and SMI? Did you actually look at what you wrote this time before you hit "Submit Reply"?

3 years and 3 phases of manned and un-manned testing are no laughing matter. That's plenty serious amounts of taxpayer money and USN effort. Whatever QC issues there may have been, the units made it through 3 years of testing and NEDU paid for special tooling to suit their needs, like a cowling, some other molds and IIRC, also the HUD tooling. Any remaining QC issues would have been dealt with during the necessary tooling up to build a larger number of them. The NEDU purpose of evaluting commercially available units was to save some time and money on R&D, then refine a commercial unit for NEDU use, not order a bunch of off the rack CCRs and then take them into combat.

There are only 2 units in the UK, and those 2 people will have to know about Alex's offer and then be willing to part with them and get them to him. Not much chance, not withstanding your "working one" dig. I've got over 500 hrs on mine now, no dives missed. How many 100's of hours do you have on any unit with no dives missed?

Prisms are still, in fact, in production and they are still being delivered. SMI are allowed to continue taking orders until Hollis is in production and ready to take orders.

They are spending an awful lot of money on "vaporware". At least Oceanic have a long standing interest in trying to bring a large production CCR to market and maybe they have learned a few valuable things from the process along the way.

Unless they plan on running the SDV up onto the beach, there will be a swim involved to get the divers to shore, and probably not an easy one. To quote the first page of the NEDU TM 01-03 document posted on the SMI site:

"The ASDS program currently needs a UBA to support a wide range of operational scenarios and depths. The current LARV and MK16 MOD O used by SOF do not meet the requirements of ASDS because of their size, depth restriction and operational reliability."

Why would they need a new unit that exceeds the above units capacities for depth and also a smaller size if they were planning on riding the SDV all the way up into shallow water?

During the ride in the SDV in the upright position, the divers won't be swimming or working, will they? So why would the upright position be "the" test point of interest? Isn't the unit WOB in the swimming-working hardest-position more important to it's ability to get the diver safely ashore? Or is this just more of your trying to push some conspiracy theory about SMI manipulating the NEDU to do their bidding? -Andy

Drmike

Alex - what would be very interesting indeed would be to test the wob on an rb80. Id be prepared to 'love you longtime' to have comparative data on that.

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Dave Sutton

Just "suggesting" what everyone who has been watching this show for the last 10+ years already knows....

This stuff has been an ongoing novel for as long as anyone can remember.

Go back and read the old NWD Rebreather List stuff and then come back. Lots there to chew on.
What is published on the SM website is pretty selective. Go read the rest.

Bottom line is that the Prism failed to meet Navy needs and is a commercially failed unit in the sports market.
That's not to say it is not a good sports diving rig, but just that it was/is a commercial failure.
More rEvo's have been made in th last 12 months than Prism's in it's entire history. Ditto the Optima.
Build quality is "variable" to be charitable, ranging from adequate to utterly terrible. Laughable in some cases.

No matter how you slice and dice that, the bottom line is that it never was a serious commercial contender.
We'll see about the Hollis version, but in the end it'll be so redesigned that it'll essentially be a new rig.


Sorry... just calling it like I see it. Don't take it personally. I'd be happy to have and dive one.
Don't forget that I earn my living working in the US Navy Test world, and for what it's worth: We'll test anything anyone sends.



Dave

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Gill Envy

Wow, we are so blatently off topic... probably best moved to a new thread with these comments:

You guys live closer to one another than most of the rest of rebreatherworld. Perhaps a rendevous is in order.

Andy, I think it's time to let these guys try and explain with their own tests how it is that you have gotten 500+ hours consistently doing 10+ hrs on a 7lb fill of sorb, in what is at best called "etreme current diving" including surprising max depths well below recreational limits. Your level of good fitness probably even puts you in the high co2 output catagory.

It would appear to me that the "commercial failure" of the prism probably had as much to do with timing, being ahead of it's time and the fact that some early build quality issues tarnished it's reputation...but it seems that a lot of styles of rebreathers started out with problems even just a few years ago...the rEvo is undoubtedly riding on the shoulders of a lot of others mistakes, having the advantage of incorporating many innovative ideas and coming on the seen as the market for mCCR rebreathers is exponentially increasing. I think both systems have many merits, they simply entered the market and build quality curve at different times.

I can see where Dave is coming from, but from what I've seen with you and the prism on some 90+ hours of those 500, it's hard to explain away.

the passive secondary and the radial scrubber appear to be champion concepts, IMHO. the radial scrubber as a design concept is just beginning to get the recognition it so deserves... the axial is soon to be a thing of the past IMHO.

You are either a statistical anomaly or the Prism deserves another look by the likes of Sutton.

Interesting to note that after poopooing radial scrubbers Paul jumped for joy when the test data came back showing his dual radial design for the rEvo outperformed the axial with a seemingly unexplainable margin.

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Gill Envy

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Dave Sutton

Just call me a skeptic when it comes to "USN Tested" as an advertising claim by SM. Those of us who suffered thru *years* of claims of "USN This" and "USN That" when the thing was a real POS from a build quality standpoint just got very tired of it, especially when it was virtually impossible to actually get one built due to production issues and build quality issues (has anything changed?) . There have been many other manufacturers of rebreathers who have had their stuff submitted to EDU for test. It's just that none of them use the fact that their stuff went to short-test as their main advertising claim. Then again, companies like Sherwood-Carleton don't need to advertise. "Three Years of EDU testing" means about a weeks test work done in each of three different years, so just take what you read on the website with a grain of salt. The WOB tests that were done were just a short-sample of the complete test series, as has been documented clearly by other posters. You would have thought that a rig on the USN short-list for purchase "might" have had the full WOB tests done...

There is no doubt that a well-built Prism is a capable rig. Note that I said "well built" because there are Prism's out there that are built like shit. "Variability" in quality seems to be a built in feature of the series. The scrubber is a good one, zero doubt at all. The rest of it is just another OTS rebreather. SM was always undercapitalized, and most of the issues of note can be taken right back to inadequate funding. The thing is virtually identical to a Mark-15 from a pneumatic flow and electronic architecture standpoint, and that's not a bad genesis. I happen to have the original prototype Prism electronics pod installed in a CCR-1000 that was their factory test bed rig, and it's always been bulletproof-reliable, so it's not as though I have any axe to grind. There is that issue still floating around about a certain engineer reverse compiling the Smithers Mark-15 pod software, but that's another story for another day.

In any event, back to the WOB issue as it has to do with accident rate. We don't have sufficient evidence of the Prism's WOB at this time, as the test that was done at EDU was not a complete one, so the discussion is irrelevent. Nobody ought to take any of this personally, it's just a discussion of hardware, not ones self worth. I'd be happy to dive a Prism... no worries. I just wouldn't invest in the firm.


Dave

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"All animals are equal, but some animals are more equal than others"


Professional Small Boy: Never Successfully Cubicled.

fireman

Yeah, this prism sound great, where can I get one...hehe

There is no point in argueing facts--they are to get looked up or tested.

Opinions are a different matter all together.

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Never Forget, and stay safe everyone.

Mike

Pity - it would have been interesting to see how they would have turned out if they had enough investment to allow the right manufacturing processes from the beginning.
Martin Parker (or Gordon Smith etc) producing the Prism design may have led to a much more beneficial outcome, both for SMI and perhaps APD.

I, of course, agree with both Andy and Dave: a well built working prism is an excellent rebreather. It's also not as common as it should be. The design does a great job of ensuring you can confidently stay on the loop in the event of some failures, the implementation seems to ensure that you are well practised at doing so.

Mike

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jradomski

not realy a hard thing to do.. the setup to read the code takes longer than to pull it.. but still less than 15minutes... turning it into usable soiurce code for modification is a small job as the code is very small..

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Joe Radomski
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All posts are personal opinions and DO NOT reflect any affiliated agency unless specifically stated.

silent running

I'm sorry about your suffering and fatigue, Dave. But exactly how much suffering and fatigue would you say you endured during these years? On a scale of 1-10, how would you compare it with say, being an American infantryman in a Japanese prison camp in the Philippines from 1941-44 as a solid "10"?

This is really choice. I remind Paul R. that the Prism has very low WOB and that a good breathing CCR need not be huge, then ask Alex for more opinion and/or info on the NEDU test criteria used on the Prism and then Dave informs us that the Prism is "a real POS". Totally awesome.

I'm not taking anything personally here, nor do I in my job at the bar. I just don't see the point of using "POS" in the midst of a perfectly reasonable discussion on WOB, testing and it's importance. -Andy