Shearwater Gradient Factors=DSAT?

[aquacat8]

I may get a chance to borrow the Shearwater as well. Thanks for all the answers guys!

 

[scubadada]

The behavior of DSAT and Buhlmann is well illustrated in the 2017 ScubaLab hyperbaric chamber testing. See the link for the testing spreadsheet in 11 New Dive Computers Tested By ScubaLab In 2017 Both 45/95 and 40/85 were tested along with DSAT and several other popular deco algorithms

 

[dmaziuk]

The big caveat in all this is DSAT's designers consider it good for no more than six days of no more than 5 tanks/day diving -- on air. And if you're pushing your bottom times: to take every 3rd day off/go easy.

It's not clear how ZHL16 stacks up for multi-day no-stop diving since most people doing that are using cheap RGBM computers. "Studies" of four chamber dives on semi-random profiles are all good and well, but I don't expect there's enough real-life data on ZHL16C in recreational diving for any meaningful statistics.

The point being, you really should factor in the duration of your entire dive trip: if it's only a weekend, then 95-ish Hi should match DSAT, and if you don't go into deco, Lo should not matter at all. If you're looking at 6+ days straight, personally I would think twice before diving DSAT to its limits in the first place.

 

[stuartv]

Its not just a question of different conservative setting but ultimately different algorithms, DSAT vs Buhlmann so they will never completely match and as tbone pointed out its best to just dive the settings you feel best for you.

That said. If you stick to rec mode your only choice to most closely match is conservative set to low. (45/95). If you elect tech mode you can futher adjust the low conservative setting up to more closely match the DSAT that has not ben modified for additional conservatism. In another thread I believe @stuartv suggested 90/95? Gradient Factors and recreational diving

Here is another relevant thread...

Algorithm question (Perdix AI vs DSAT)

For the record, with a Shearwater, if you do not exceed your NDL, the GF Lo number is not used. It's only GF Hi that matters. Once you exceed your NDL and cross over into mandatory deco, then the GF Lo setting determines what the depth is for the first deco stop.

 

[uncfnp]

For the record, with a Shearwater, if you do not exceed your NDL, the GF Lo number is not used. It's only GF Hi that matters. Once you exceed your NDL and cross over into mandatory deco, then the GF Lo setting determines what the depth is for the first deco stop.

I thought that as well but then it seems I saw a post (or two) that suggested it might play a role in multiday repetitive diving. No?

 

[Jay]

Does anyone know which gradient factors my Shearwater diving buddies would set to match my DSAT? My buddies are lucky enough to have Shearwaters!

Here's some more NDL analysis on ScubaLab's exercises. Place of dive tables in modern diving ... but in summary it's as per @scubadada's post above (and of course with an obvious caveat that its a mere snap-shot i.e. it holds true for those profiles with those SIs and for a single day's diving ... and keep in mind the volatility of those NDLs especially during the ascent phase).

I thought that as well but then it seems I saw a post (or two) that suggested it might play a role in multiday repetitive diving. No?

Do you happen to know where that was said? I've not seen it ... (and here's a link to my reading list on this which I think covered most of those threads (post 54: So, who is going to market an inexpensive rec computer running Buhlmann with GF?)). I doubt that can be correct because a/ given GF Lo isn't relevant at all on day 1 or dive #1 , how can it be on day/dive# 2 etc. And after a certain SI (overnight), the watch must be clean (I can't find what that SI is in the Teric manual).

The multi-dive multi-day (let's call it a 'LOB' trip, 4 dives/day, 5 days of diving, 2 hour SIs) of a particular GF Hi versus DSAT NDLs on NDL diving is an interesting question that might be unanswerable at this point in time?

Here's a table I saved a while ago - I'm fairly certain it originally came from @scubadada :

View media item 204278

 

[tursiops]

The big caveat in all this is DSAT's designers consider it good for no more than six days of no more than 5 tanks/day diving -- on air. And if you're pushing your bottom times: to take every 3rd day off/go easy..

You've said this several tmes, I think based on the original paper on the DSAT work some 25-30 years ago, no? Since then, it would seem the empidemiology would suggest DSAT is much safer than its developers thought it might be.

 

[KenGordon]

You've said this several tmes, I think based on the original paper on the DSAT work some 25-30 years ago, no? Since then, it would seem the empidemiology would suggest DSAT is much safer than its developers thought it might be.

What ‘empidemiology’? Until you approach the limits you are just jumping in and swimming about. Which computer you have doesn’t matter. We have no data about the number of divers, the number of dives they do, how close to limits they dive or which set of limits they are using.

In the U.K. we do have data about the number of people treated at chambers, about 350/year. We also have some analysis of about 70 of those decompression incidents (plus/minus those that don’t go to the chamber) and about 30 are within tables/computers. People are definitely getting bent.

 

[scubadada]

I thought that as well but then it seems I saw a post (or two) that suggested it might play a role in multiday repetitive diving. No?

I don't think so. Only kicks in when you exceed deco and then dictates depth of 1st stop. However, MultiDeco takes it into account In every plan. It's interesting that Buhlmann can be implemented in different ways. It makes me wonder if there are differences in how it is implemented in dive computers and/or other planning software. If someone was compulsive enough, they could put it to test.

 

[aquacat8]

The big caveat in all this is DSAT's designers consider it good for no more than six days of no more than 5 tanks/day diving -- on air. And if you're pushing your bottom times: to take every 3rd day off/go easy.

LOL my body says no to that anyway! My body is like my old convertible car: she looks pretty good if you don’t get too close, but it's best to be gentle on her.