Moving from Suunto to Shearwater
- Sami Ihalainen
- 1 day ago
- 8 min read
My thoughts on changing computer brands and a look into the Shearwater product line.
I had been a Suunto dive computer user for nearly 20 years. Ever since I did my Open Water Course in 2006, I had only done maybe a handful of dives where I didn't have a Suunto computer on me. I knew the whole lineup in and out and liked it. I didn't even have a problem with the widely criticised conservativeness of their RGBM algorithm.
I had of course been following the meteoric rise of Shearwater in the past years. They've become famous in the dive computer world for having great products (for both recreational and technical diving needs) and even better customer service. Even though I resisted in the beginning, slowly over time I became pretty convinced that this was the way I should be moving towards computer wise and I stated to want one. However an expensive purchase of this size didn't seem to make sense when I had a perfectly functioning, albeit a little dated, top of the line Suunto that was even Trimix and CCR capable. I had a want, but not a need.
The need
“Luckily” for me this changed in early 2024 when Jo sent my colleague Kelly and myself to Honduras for two hard weeks of technical diving and PADI Tec instructor training. Not that I wasn't aware of it beforehand, but during these dives it became really apparent for us how mixing different algorithms within the team complicates planning and conducting decompression dives. Most technical divers nowadays use computers with the Bühlmann ZHL-16C algorithm with adjustable gradient factors, and our course used this model for the dive planning software. It's not just technical diving either, the Bühlmann is a very popular algorithm in all levels of dive computers. Suunto however, until very recently, has stayed with their proprietary RGBM algorithms. (For more information on dive computer algorithms check out this great article from scubatechphilippines.com.)
On some of the first decompression dives of the course, my Suunto DX with its Fused RGBM algorithm actually cleared the deco stops faster than the Bühlmann computers we had, but as we progressed this radically changed. Oh and don't worry, I was also using a different borrowed computer with algorithm matching the team, but had the Suunto along for the ride specifically to test this.
As our training dives progressed the Suunto started to barely finish the stops when we were already ascending to the next one and soon enough, it was giving a wildly different decompression plan (including additional deep stops). We of course followed our main computers and our pre-written “paper plans” and I let the Suunto “get bent”. It protested for a bit, but soon quieted down and it was becoming apparent to both of us that the end of our time together was starting to loom ahead.
So after the course it was clear that I needed a computer with a Bühlmann algorithm, badly. I had a brief comparison with other brands before making the commitment, but it was pretty clear from the beginning that this indeed would be a Shearwater. The next decision to make was which one(s)?
Choosing the right one
Shearwater's current flagship product I would say is the Petrel 3, a wonderful computer that, depending on the model, can even be plugged into a rebreather to monitor the cells. It actually (with its predecessors) comes with a lot of rebreathers as their main hardwired computer. This is also the priciest of their wrist computers with the largest form factor. Also their even fancier HUD model ‘NERD 2’ fills a similar role alongside the Petrel 3, but rather that on your wrist it sits right in front of your mask for hands free use. These seemed like overkill for me, especially considering the price.
For years I gravitated towards their Teric model, which is a great tech-capable computer that is also watch sized. I wanted to also be able to wear it as a daily watch so I could to show everyone what a cool diver I am. However a few years back I started wearing an Apple Watch to track my activity and health. Me being a geek for the data it provides there is no way I am taking it off now. So I didn’t have a need for a cool watch anymore. Also I would get the advantage of a bigger screen moving away from a watch size.
Alongside the Teric is the Perdix 2, which is pretty much the same computer capability wise. The main difference comes in the form factor: the Perdix line is bulkier and has a bigger screen. This also affects the battery life. This is where a big convenience for many of us comes to play. While the Teric has a rechargeable internal battery and needs to be plugged in, the Perdix takes normal AA batteries! And swapping to a new battery is super easy. 1.5V lithium battery is recommended but any old AA will do, rechargeable or not. Vibration alerts are disabled for some battery types though.
This all made sense to me and I officially decided to go with the Perdix 2 as my main computer. Unfortunately this wasn't the end. You may or may not know this, but for technical diving almost everything needs to be redundant. The redundancy for a computer could be a written plan (which we do regardless) and a timing device. However in todays world a second computer just makes more sense. With the differing algorithms, this role still could not be taken by my Suunto unfortunately. So the pain of decision making kept going.
Another Perdix 2 would have been the obvious choice if I had an unlimited budget, which I sadly don't. Next on their lineup were of two smaller watches, the Tern and Tern TX. These are more recreationally focused computers but still are capable technical diving computers for most. The difference between the two is that the TX model has a digital compass and supports wireless air integration while the standard Tern doesn't do either. This could have been a nice choice if I was running out of wrist and arm space, but I didn't have this issue.
Moving down the line we arrive to the Peregrine. This computer has taken the world by storm. It has become super popular in the recent years and you see many of our recreational divers on the boat wearing them constantly. It is extremely affordable for the value it provides. Like I just said for the Tern, the Peregrine is also recreationally focused but capable enough for majority of technical diving. Essentially the Tern is a watch-sized version of the Peregrine.
The capability and affordability made the choice clear and I went with the Peregrine as my second computer. For me the standout feature of the Peregrine is the battery life. I only take mine out of the drawer for technical dives, but I have owned it almost a full year and it still has battery left from the factory! The battery is internal and wirelessly rechargeable.
Soon after receiving our computers I noticed that they had released a new computer, the Peregrine TX. Unsurprisingly these letters added the digital compass and wireless air integration to the Peregrine, just like in the Tern family. I felt a little sad missing this option, but also it would have made my agonizing over the options a lot harder to be honest.
I didn't need my backup to be air integrated anyway, but if you're looking into a new primary computer, I would take this model (or the Tern TX) into serious consideration! That is unless you're ready to spend a little more and go with the Perdix 2 as its obviously the best computer in the world because I have one.
The transmitter
Having gotten used to air integration with my latest Suunto, I definitely wanted to keep with it. So naturally I got Shearwater's Swift transmitter with my Perdix. This has definitely been an upgrade from my older Suunto Transmitter (not the be confused with the newer Tank Pod). The advantage is that the Swift is paired with the computer using the serial number and thats it. The older Suunto sent out a code you connected to and it could be changed if your dive buddy’s transmitter was sending the same code for example. Problem with this was that the code change was initiated with a sequence of pressurizations and de-pressurizations. If you have ever tried to re-seat a slightly leaking o-ring, you might see an issue with this. I experienced accidentally changing the code every now and then, usually realizing in the beginning of the dive that I wasn't connected. That prevented me from geeking over the air consumption data after the dive, very annoying!
I really like the design of the Swift and its also supposed to be more resilient to interference from other transmitters and be able to adjust its transmission timing to prevent this issue. However I have to say that even with the Suunto I have never fully lost connection underwater. If it was working in the beginning of the dive, I never lost the connection during. Diving with underwater scooters have caused the temporary lapses in the connection, but thats easily fixed by stopping the scooter for a few seconds every now and then.
However after using the transmitter a few times, I am not a huge fan of the fact that the Swift only turns off when the pressure on the regulator is 0bar/psi. As a dive professional you might often find yourself setting up your gear in advance and I definitely do this. Sometimes even on the previous day. You might see the issue already, but if I fail to fully de-pressurize the regulator after checking the tank pressure, I might leave the transmitter transmitting overnight and waste a bunch of the battery life. This of course is just a user error I needed to get used to.
Once in a while I love to borrow a second transmitter from Kelly and go for a sidemount dive and have both of my tanks connected. When I do this I take advantage of the sidemount mode on the Perdix. This connects to both of your tanks as a primary gas and knows this while calculating SAC rates for example. Also it can remind you to switch to the other tank in pressure intervals of your choosing, if you wish to use this feature.
The app
One thing I really like on the current setup is how easily I can upload the dives from the dive computer to my phone. With the newest version I just have to turn on the bluetooth on my dive computer and open the app on my phone and the transfer happens automatically to the phone and from there into the cloud. It was a pain with the older Suunto using my laptop and a cable, if the software worked at all, so I really didn’t end up doing it much. Now all my post-switch dives are securely stored.
I do have to say that even though it works, I am not a huge fan of the Shearwater app. It is very clunky to use and how it works seems really outdated. All the data I want is in there, but the experience using it leaves a lot to be desired if I'm being honest. In my mind this is the weakest point in my Shearwater user experience and I hope this will get an update someday.
See? I said something negative, I hope now I won't be told that this is an #ad, even though it certainly might sound like it at points.
——
Wow, that was a lot of rambling about ‘the Shearwaters’ from the top of my head. Thank you for our years together and good luck in the future Suunto, but despite our shared country of origin, seems like I'm a dedicated Shearwater cultist user now.
Safe diving everyone, with deco or without!
-Sami @ Divetech
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