Sherwood Wisdom Opinions

Hello Wet Ones,

I am very fond of my 5-year-old Suunto Cobra. It's proven exceptionally reliable over 300 or so dives and gives me all the info I want clearly and logically. However, its conservatism has been limiting at times. This has been largely made moot by my conversion to Nitrox diving over the last few years. However, next fall I'm signed up for two weeks in Raja Ampat on Deb Fugitt's photo liveaboard on the Ondina. They do as many as seven dives a day and there's no Nitrox available.
I'm considering switching to a more liberal computer to keep me out of deco. Have you had any experience with the Sherwood Wisdom? If so, what are your impressions and, better yet, could you compare to the Suunto?

Thanks much.

Best Regards,

I used a Wisdom up until recently and have switched to a Cobra. The biggest difference to me is that the Wisdom will be happy for you to surface well into the yellow in Nitrogen loading while the Cobra wants you in the green. You can push the Wisdom into deco on your first dive and then it defaults to the Navy tables and wants you to do your deco at a 10 ft stop. That's a PITA. It also keeps track of your N2 loading and and makes you pay for surfacing in the yellow by giving you a very short NDL on the 2nd dive. Then it's back to the 10 ft. deco stop if you exceed the NDL. The Wisdom is "liberal" only to the point of letting you push the NDL once and then it gets pretty demanding on the next dive. Plus just unclipping it and moving it to you face to look at too fast will set off the alarm for a too fast ascent.

I don't see how any computer can keep you out of deco with that many repetitive dives. You might be better off using software and the Suunto in guage mode.

Actually, the wisdom is simply an aeris / oceanic computer with the Sherwood name slapped on it. If you look at it turned sideways, you will see it is virtually identical to the Aeris AI. All of these computers use the same algorithm... and it's not something that switches to Navy tables if you get into the yellow... It's basically just a modified version of the DSAT - Padi tables.

You will find it will run about 9 minutes more liberal than your suunto on a 60 foot dive... and when you take that times your 7 dives a day, you are gaining an extra dive at least.

When I was in Chuuk, the folks diving the suunto could not get as many dives as those of us with the pelagic (aeris, oceanic, Sherwood, genesis) computers. In fact one guy borrowed my backup for the rest of the week as he was frustrated with the limits on his bottom time during a once in a lifetime trip.

So if you want another air integrated computer with a more liberal algorithm, then Cochran will be the most liberal, followed up very closely by the palegics.

scubatoys:

Actually, the wisdom is simply an aeris / oceanic computer with the Sherwood name slapped on it. If you look at it turned sideways, you will see it is virtually identical to the Aeris AI. All of these computers use the same algorithm... and it's not something that switches to Navy tables if you get into the yellow... It's basically just a modified version of the DSAT - Padi tables.

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Well, Larry, I didn't say that. I said if you push the Wisdom into DECO mode, it reverts to the Navy tables. It lights up and beeps like crazy and flashes DECO and makes you do a long stop at 10 feet to clear your deco. We ain't talking 60 feet here. And after clearing your deco, the old Wisdom is not happy at all. You had better be doing a sub-60 foot dive on Nixtrox 36 to get any bottom time out of it.

The other thing I said is that the Wisdom is perfectly OK to let you surface in the yellow and the Cobra wants more hang time to clear into the green. That's not DECO mode.

If you are really diving the NDLs into the deco range, I would run software instead.

scubatoys:

Actually, the wisdom is simply an aeris / oceanic computer with the Sherwood name slapped on it. If you look at it turned sideways, you will see it is virtually identical to the Aeris AI. All of these computers use the same algorithm... and it's not something that switches to Navy tables if you get into the yellow... It's basically just a modified version of the DSAT - Padi tables.

Click to expand...

I'm a satisfied owner of an Oceanic/Pelagic Data Plus 2 and have never seen the sort of penalties for going into deco that Redhatmama refers to. I've just seen it appropriately track assumed compartment loadings. Leaving the water just as required deco clears will often leave the middle halflife compartments very heavily loaded. This, combined with "surface credit control" (increasing the halftime of faster compartments to 60 minutes once you surface) will leave those compartments heavily loaded for your next dive. IMO, that is an accurate reflection of reality.

OTOH, as Redhatmama says, it DOES switch models between NDL and deco. The DSAT model is an NDL model only. To be more precise it has surfacing M values only, and does not have any delta-m values to change the M-values with depth. This means that it is not possible to use the DSAT model to calculate decompression stops. It doesn't appear that Pelagic used the standard USN/ Workmann M-values, but instead modified them to minimize the discontinuity between NDL and deco modes.

Charlie, I'm a bad girl and have taken the Wisdom below recommended recreational diving limits. My Wisdom (and it was one of the first models) states in the manual that it uses the Navy tables in deco mode. It's not well suited for deco diving.

The reason I switched to Suunto was because my Wisdom just kept crapping out on me and I have a local Suunto dealer who will swap out the computer if this one craps out instead of having to send the Wisdom off for repairs.

I can make my Suunto happy if I do the extra hang time and I make sure I have the gas to do it. I've gotten a bit bored and sometimes cold doing 11 minutes instead of 3. It is possible to do the same dives if you have the time and gas. I've never done 7 dives in a day and really don't know how either computer would handle that. I'm afraid my body would go into siesta mode after dive 3 and maybe revive for a shallow 4 night dive.

I'm now leaning more toward using software if I'm going to dive deep and incorporating deep stops in my plan.

redhatmama:

My Wisdom (and it was one of the first models) states in the manual that it uses the Navy tables in deco mode. It's not well suited for deco diving.

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While the Pelagic computers aren't targeted to the intentional decompression market, I have had not any problem using it for mild deco (10 or so minutes max required deco). Just because it shows a ceiling depth of 10' doesn't mean you have to zoom right up to the ceiling. As with all diving, one needs to have the gas to do the desired profile.

The Pelagic model in decompression is based, rather loosely IMO, on the Navy tables, or more specifically, the Workman 1974 model. My Oceanic computers don't show the huge discontinuity that would exist if it was using unpadded USN/Workman model ---- if it did, then on an 80' dive the Wisdom would be NDL for the first 31 minutes, then show 0 NDL but no required stop for 10 minutes or so until you reached the limits of the USN table/Workman model.
(USN table is has 40 min NDL for 80', PADI has 30 minutes for 80' -- leaving a 10 minute gap between them.)

I haven't tested the Wisdom specifically, but I know my Oceanic Data Plus and Data Plus 2 computers don't have that sort of discontinuity, so it appears that the USN table/model is scaled back and made more conservative. I wouldn't be surprised if the USN values were scaled back to the DSAT values at the surface, and then the USN slopes or delta M's were used.

We need to take what the manuals say about deco models with many grains of salt. For example, many "buhlmann-based" computers use "a" coefficients much more conservative than even the ZHL16C model.

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I'm surprised that you were unhappy with the conservativeness of the Wisdom, but consider the Cobra to be liberal enough for your diving.

Well, thanks folks...I think! To use an unfortunate pun, I'm out of my depth when talking about M values and delta m values. I had gathered from Scuba Diving's computer reviews that the Sherwood was more conservative than the Aeris/Oceanic models. If it is, as I gather from your comments, basically the same as those, then I think I'll stick with my original Plan B: I have an Atmos II that I bring on liveaboard trips as a backup (wearing it on each dive just in case my Suunto craps out). I also have a backup SPG. If my Suunto becomes unhappy, I'll revert to the Atmos and use the Suunto in gauge mode or abandon it altogether and go with the SPG for gas pressure.

Thanks. Saved me some dough.


Best,

peterjmaerz:

Hello Wet Ones,

I am very fond of my 5-year-old Suunto Cobra. It's proven exceptionally reliable over 300 or so dives and gives me all the info I want clearly and logically. However, its conservatism has been limiting at times. This has been largely made moot by my conversion to Nitrox diving over the last few years. However, next fall I'm signed up for two weeks in Raja Ampat on Deb Fugitt's photo liveaboard on the Ondina. They do as many as seven dives a day and there's no Nitrox available.
I'm considering switching to a more liberal computer to keep me out of deco. Have you had any experience with the Sherwood Wisdom? If so, what are your impressions and, better yet, could you compare to the Suunto?

Thanks much.

Best Regards,

Click to expand...

I dove a Wisdom for a couple of years. The only comparison with a Cobra I can make is during a trip to Belize - 2 dives a day, 4th day did the Blue Hole (3 dives), 1st dive to 140+ with ascent starting at about 8 minutes and another 25ish at 30 feet, 2nd and 3rd to 80ish, avg 50-60 and 45 minutes. The Wisdom did just fine. A friend of mine did a slightly shallower profile, maybe 10 feet or so but similar times. He was diving a Cobra and it locked him out during the 3rd dive.

For the type of diving you're planning either get a computer that can handle deco diving and keep running or dive tables and use the computer in gauge mode.

In my experience the Wisdom is very liberal.

It is also very ammenable to being a backup computer on a deco dive. The Navy table default is liberal enough that no matter what I do with my primary DPlan schedules, deep stops, accellerated deco, etc, it's ready to come out of the water when I am.

So I think it's a great computer but would suggest that divers consider extending a safety stop above 30 ft until it's in the green on multi-day repetitve dive profiles as it is pretty liberal.