Diving Shearwater with a Suunto buddy

[Landau]

It's not just the brand and algorithm but the conservative setting.

I dive a Suunto Eon Core set at the default. One of my favourite buddys dives a Shearwater Peregrine which is set to high conservatism. She always runs out of no-deco time first.

Another buddy sets his Suunto Eon Core to a more aggressive setting and with him I run out of no deco time first.

None of this is an issue. We always just dive according to the most conservative computer or personal stetting and find lots to see.

Those worried about the computer preventing them from getting an extra few minutes or locking then out for not following its instructions are not people I'd choose to dive with.

 

[boulderjohn]

I have done more than a few dives using Shearwater computers while my buddies used others, including Suuntos. You can set the Shearwater to make it as conservative than a Suunto--or even more so. Then you will all be about the same.

Think about what that means for a minute.

Even though they won't admit it, people seem to think the computer determines your body's decompression status. In reality, your body's decompression status is whatever it is--the computer just tries to make an educated guess about it. If you set your computer to a greater level of conservatism, you are intentionally overriding its best educated guess to add a padding of safety.

So what is the difference between ascending when your buddy's computer says to do so (while yours says you still have time) or ascending when your computer (set with added conservatism) says to end the dive? Either way you are going to end the dive when your buddy's do. You might as well do it with the computer you want to use the most.

 

[ginkgo]

How do you set a Shearwater to be as conservative as a Suunto? That would be the perfect solution here.

 

[tridacna]

You can do some tech with the Tern...just not Trimix or CC.. It works to 120m and allows three gasses. It has "full decompression support."

Aha. So you're advising budding tech divers to get a Tern. Excellent advice.

 

[MidOH]

How do you set a Shearwater to be as conservative as a Suunto? That would be the perfect solution here.

As soon as you switch the Terric to Technical Mode to use the extra gauge reading spots, it'll select a more conservative algorithm.

On identical dives in Roatan, with dive buddies who didn't adjust their computers, my Terric was going into light deco on every dive, that cleared during the dive, due to the rolling hills kind of Roatan dives. It didn't do that in Rec mode.

I could adjust it to a less conservative setting, but there's no need. It seems safer, as is.

IIRC, you can select 2 or 3 presets, or dial in your own numbers. I'm on medium tech, I think. I'll check.

 

[MidOH]

Yep, it's set to GF Conserv. Med 40/85.

The default High is 35/75.
Low is 45/95.

I choose the Terric because I can wear it 24/7 on vacation. No theft worry. No issues so far. Wireless charger is nice.

 

[rongoodman]

How do you set a Shearwater to be as conservative as a Suunto? That would be the perfect solution here.

Since the Suuntos use various proprietary algorithms, there’s really no way of knowing what they’re going to do. They’re more or less based on a bubble model, so they’re never going to map directly into Buhlmann’s dissolved gas model, and they seem to have added various tweaks to that. You can make the Shearwaters more conservative in an NDL setting by choosing a lower value for GF High.

 

[rongoodman]

As soon as you switch the Terric to Technical Mode to use the extra gauge reading spots, it'll select a more conservative algorithm.

Same algorithm, it just defaults to 30/70 in tech mode.

 

[MidOH]

I must have inputted a more aggressive rec setting then, before the change to tec mode.

 

[boulderjohn]

How do you set a Shearwater to be as conservative as a Suunto? That would be the perfect solution here.

You can make the Shearwaters more conservative in an NDL setting by choosing a lower value for GF High.

Years ago I was using 50/70 for tech diving, and I didn't bother changing it when NDL diving. With a GF high of 70, my Shearwater was more conservative than a Suunto, especially on a first dive. I learned that diving with a friend with a Suunto Cobra. I would be regularly going into deco when he still had a little time. Because I am not an idiot, I knew that if I had taken a minute or two to change the GF high of my computers I would be fine and still be well within the true Buhlman NDL. Because I had stayed in tech mode, I would have a minute or two of required deco stop at the end of the dives, which would thoroughly clear before my friend was done with his 3-minute safety stop countdown.

As I said, I am not an idiot, so I knew I wasn't really in deco. However, ScubaBoard does have its share of idiots, so when I described the above practice years ago, one of them started a new thread about how I, as an instructor, was advocating going into decompression on NDL dives for people without proper training and equipment. He did not quote me--he just claimed I was advocating untrained divers going into deco. It was three days before I found the thread, three days of people calling me scum and saying I should be banned from ScubaBoard for advocating unsafe practices. When I found the thread, I linked to what I had actually written, and opinions changed--except, of course, for those who had left the thread after deciding I was a total jerk.