Scuba Board users hate Suunto. This is a kind of anti-viral marketing thing. On the other hand they love Shearwater and Deep 6/previous brands from the same bloke due to 1) shearwater being nice computers, 2) proper viral marketing efforts, having SB users as dealers etc.
The hatred for Suunto comes for three claims 1) they are unreasonably conservative and you will have to get out of the water too soon 2) they will lock you out for minor “violations” 3) they use a proprietary algorithm and so you cannot use “open source” planning tools, write your own or match the computer exactly against another computer using an “open source” algorithm.
I believe this is an irrational and uninformed hatred based on received wisdom, group think and an obsession with NDL as a measure.
I own (and use) both Suunto (mostly a Helo2) and Shearwater (Perdix and a Petrel on a CCR). I dive with people with both Suunto and Shearwater computers. The odd person has an Aqualung or Mares. I have an Ocenic I lend out and I have been using an Apple Ultra with the Oceanic+ on recent dives to see how it behaves. I dive the Shearwater with a GF setting of 50/85 or 50/80 (depending on the seriousness of the dive). This is approximately the “medium” conservatism.
I dive in the U.K. in cold water and doing two dives a day with a decent surface interval. Occasionally I go abroad and do the four dives a day warm water thing or the two dives in the morning thing that seems typical of the warm water holiday diver. U.K. divers are generally trained for deco and so NDL is not always the limit to dive dive.
For fun (and to vaguely properly understand how it works) I coded up SB’s favourite deco algorithm (Bulhman GF, as seen in Shearwaters and now lots of computers - including as an option on Suunto’s top of the range Eon Steel).
I generally find that there is not a huge difference between the dives I can do, including no deco dives, between the Suunto and Shearwater. A significant difference can happen if I am forced into an unreasonably short surface interval by some unreasonable tropical diver operator. This is because the Suunto algorith has additional “knobs” which increase conservatism in a number of circumstances which might be regarded as bad diving practice. This, when compared to, for example Oceanic or a GF of something/95 (Ie Shearwater set to aggressive) means that a Suunto with have a shorter NDL on a second dive following a short SI (eg an hour).
For actual data points, on a recent OC deco dive (35 minutes at 36m on 27%) after 15 minutes of stops the HelO2 (on most aggressive setting) was clear, 5 minutes later the Apple Ultra (50.85) was clear and 2 minutes later the Shearwater (50/85) was clear.
So I don’t think Suunto is especially conservative Compared to what I am prepared to dive at least. I have dived with some proper experts too, and I don’t see them setting their Shearwaters more aggressively than I set mine.
Lockout is another favourite. To lock out a Suunto you have to stay above your ceiling for 3 minutes. This means you have to be in real deco (not a safety stop or a Pyle style deep stop) and go too shallow for quite a long time. The only way that happens is if people completely ignore their computer. There might be some corner case in a cave someone will contrive but really it never happens. I dive with lots of people, in a club, using Suunto’s and I have never seen one bent accidentally. I have bent a Zoop using it as a bottom timer on a trimix dive. I have bent the Oceanic+ App on the Apple Ultra not respecting it’s idea of a safety stop - that was no surprise as I was decoing on a rich mix and it had no idea what was going on really - as I was following the Shearwater.
No computer is going to make your dive more fun. They can make your dive less fun, be difficult to use or hard to see. Those are the attributes that a sensible person ought to be looking at When choosing a computer. And the price…
A definite advantage of the Shearwaters is that the resale price holds up well due to the fan base.
