PfcAJ
Contributor
What's the whole "GF thing" exactly?
Why are the Shearwaters held in such HIGH REGARD?
- Thread starter Michael Thomas
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That the users do not understand them enough to make informed choices about how to set their computers. Also that the planning tools do not all agree on how the numbers apply. For example subsurface and multideco treat the low GF value differently. Maybe one matches the computer, maybe not.
That comes back round to the lack of a planner from Shearwater.
Hello,
I use a Shearwater NERD on my rebreather. It is an extraordinary piece of equipment which I honestly worried I might not like (because of where it sits) but which I now love. I have absolutely no doubt that having that display (including PO2 from all cells) in my field of view at all times, and having that display completely independent of rebreather electronics, makes my rebreather diving safer.
In relation to Shearwater in general, most of what I would say has already been said. Only a couple of things to add.
I have immense respect for them as a company. I teach on many of the high end diving medicine courses offered in the US through organizations like DAN, the UHMS and NOAA. I also attend the UHMS and SPUMS meetings every year. Bruce and Lynn Partridge frequently attend these courses and meetings, and if they are not there themselves a member of the Shearwater team often is. In other words they invest heavily in maintenance of their own knowledge and that of their staff in the advanced aspects of diving medicine and physiology. No one else does this as consistently.
I don't think the planning thing is a big deal because there are so many easily accessibly planners for gradient factors out there. Also I am not really sure what KenGordon meant when he said....
"The whole GF thing is another issue".
... however, if it is intended to be a negative comment then I would disagree with him. I think GF is exactly where technical divers need to be at present.
Simon M
I use a Shearwater NERD on my rebreather. It is an extraordinary piece of equipment which I honestly worried I might not like (because of where it sits) but which I now love. I have absolutely no doubt that having that display (including PO2 from all cells) in my field of view at all times, and having that display completely independent of rebreather electronics, makes my rebreather diving safer.
In relation to Shearwater in general, most of what I would say has already been said. Only a couple of things to add.
I have immense respect for them as a company. I teach on many of the high end diving medicine courses offered in the US through organizations like DAN, the UHMS and NOAA. I also attend the UHMS and SPUMS meetings every year. Bruce and Lynn Partridge frequently attend these courses and meetings, and if they are not there themselves a member of the Shearwater team often is. In other words they invest heavily in maintenance of their own knowledge and that of their staff in the advanced aspects of diving medicine and physiology. No one else does this as consistently.
I don't think the planning thing is a big deal because there are so many easily accessibly planners for gradient factors out there. Also I am not really sure what KenGordon meant when he said....
"The whole GF thing is another issue".
... however, if it is intended to be a negative comment then I would disagree with him. I think GF is exactly where technical divers need to be at present.
Simon M
packrat12
Contributor
I also use and love the NERD. I have enjoyed meeting Bruce and Lynn a number of times. They are always present when at a technical diver gathering. I have seen and talked with them at TeKDive USA 2014, 2016 and at DEMA!! No other computer manufacturer has that exposure.
PfcAJ
Contributor
I think your first point isn't a fault of the computer. The users lack of understanding isn't a problem with the unit.
Your second point has to do with model implementation. I don't know anything about subsurface but if the assumptions are all the same (gas, gf settings, ascent/ descent speed, etc) you should get the same result across the board. Not sure how a difference between multideco and subsurface = a problem with a shearwater dive computer in any case.
And what do you mean by "treat the low gf value differently"?
I think that the planners do not always match the computers as there is no specification for GF.
In another thread it became apparent that various members of this board believed that the GF Lo did not matter for a no stop dive. Part of the reason was that trying it they found that the value they set did not make a difference. Some examples were planners, some dive computers.
So the question arises, where in the dive does the change over between GF lo and GF hi happen? Starting at the bottom? Starting at the first stop? And if at the first stop what if there are no stops? Is the GF lo the limit at surfacing (the surface being the first stop) or is it GF hi (the surface being the last stop)?
So if I plan a 25% 30m 17 minute OC at GF 45/85 dive on a Petrel it is no stop. On Multideco it looks like this:
Decompression model: ZHL16-C + GF
DIVE PLAN
Surface interval = 5 day 0 hr 0 min.
Elevation = 0m
Conservatism = GF 45/85
Dec to 30m (1) Nitrox 25 30m/min descent.
Level 30m 16:00 (17) Nitrox 25 0.99 ppO2, 28m ead
Asc to 9m (19) Nitrox 25 -10m/min ascent.
Stop at 9m 0:54 (20) Nitrox 25 0.47 ppO2, 8m ead
Stop at 6m 1:00 (21) Nitrox 25 0.40 ppO2, 5m ead
Stop at 3m 1:00 (22) Nitrox 25 0.32 ppO2, 2m ead
Surface (22) Nitrox 25 -10m/min ascent.
which is consistent with 45% at 9m and 85% leaving the 3m stop.
I'll cover the user bit in another reply.
Regarding Shearwater, I'll add not just great customer service, but also transparency. Shearwater participates on this board, and has in the past been very responsive to questions. And not just canned responses--some questions have received quite detailed responses from someone with engineering knowledge. In contrast, I have seen responses from other manufacturers that I have felt are avoiding answering the question, not being candid. It's very refreshing to see a company doing that. It adds a human element to the company--I feel I know who is out there. The information on their website is great, and all their manuals and other written material are well written. The total effect of all that on me is that I feel they stand behind their products 100% and will stop at nothing to ensure their customers are satisfied.
I think that not understanding how a thing works and what the controls do is a problem. It is not the fault of the computer but a disadvantage of that computer as far as a user is concerned. If they don't properly understand the repercussions of the settings they may find themselves in difficult situations.
The existence of the extensive deep stop threads, talks at shows on how to choose GF numbers and questions in the wild from people owning these "what numbers should I use?" somewhat indicates that this is not well understood.
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@KenGordon your logic is flawed. At least with the Shearwaters you have the option to learn how to manipulate the GF. If you buy computers from just about any other manufacturer you don't get the choice to learn how to control the decompression profiles. Shearwater has recreational nitrox mode, if you don't understand GF's, use that mode. Very simple
I buy Shearwaters because they are the best (as I mentioned upthread), and because it's great having such terrific customer service. Two Petrels, a NERD, and the controller on my CCR is a modified Petrel as well (one of the reasons I went with the JJ).
But also I take every opportunity to talk them up here and elsewhere, because I think that a company that puts such an emphasis on customer service, ongoing research and continual improvement of their products deserves to be well compensated. The only reason that great companies stay in business is if people support them. I'm doing what I can to make sure that they are around for a long time...
But also I take every opportunity to talk them up here and elsewhere, because I think that a company that puts such an emphasis on customer service, ongoing research and continual improvement of their products deserves to be well compensated. The only reason that great companies stay in business is if people support them. I'm doing what I can to make sure that they are around for a long time...
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