Differences in computer ascent recommendations between buddies?

[Jcp2]

I was taught to trust and follow my computer, to stick close to my buddy, and to ascend when the first person on the buddy team reaches a preset ascending pressure. What is the best protocol to use during the ascent when the two computers, from different brands (and presumable different decompression algorithms) between the two of us have significantly different safety stop recommendations, both in terms of time and depth? For example, one of us might have a deep stop at 50 ft for 1 min while the other may not have one at all. Another would be one of us having a shallow stop at 20 ft for 2 min while the other has one at 10 ft for 3 min. Do we both stop at the first indicated stop between the two of us for the longest indicated period of time between the two of us, and then ascend together until the next indicated stop, no matter which computer it is? Could that possibly mess up our reserve gas amounts, or will the computers "catch up" and be relatively together as we go up? What if one person is on air and the other person on nitrox?

 

[loosenit2]

 

[Kimela]

My thought is that you try to figure out a way to get everything synced up (make sure you're both diving the same gas, set to the most/least conservative setting available settings). *I* would go with the most conservative - but if it's a minimal difference you might both agree to go with the least conservative. Either way, you need to agree ahead of time and stick with the plan (plan your dive and dive your plan). I dive with two computers - one is more conservative than the other - and I choose to go with the least conservative. But if my dive buddy needs to ascend earlier still, I go where he goes (and vice versa). In 'real life' I can't imagine it's a huge variable anyway - but I could be wrong.

 

[dmaziuk]

There are no "different recommendations for safety stop". If you have mandatory stops at depths, they are decompression stops you are on a decompression dive. If you are on a planned decompression dive, both buddies follow the exact same plan with exact same stops. If you are on an unplanned decompression dive, a) you shouldn't be and b) you follow the more conservative of the two computers, just to be on the safe side.

 

[Jcp2]

These are all NDL dives. I’ve not really considered this before as my daughter and I have the same model of computer, with all the settings (safety factor, PPO2, deep stop on/off) set the same and on the same breathing gas. However, if I’m diving with other divers, that may not be the case. The deep safety stop is an option that I can turn on or off. I know it’s not a mandatory deco stop because my computer would lock me out for 24h if I did hit deco.

 

[dmaziuk]

No. If you go into deco, complete its calculated decompression schedule, and it locks you out, you should take it back to the shop and demand your money back because they sold you a defective one. It's when you omit mandatory decompression, then it locks you out.

The only scenario in which your concern makes sense, is if the "other diver" goes into mandatory decompression while you're still within no-stop time. Then you have to choose what to do now, and whether you want to ever dive with them again.

 

[Foothills]

If you haven't planned your dive, and the dive team is in the situation where their computers are as dictating different ascent profiles (which can happen with the same computers & algorithms if one diver hangs 5 or 6 feet shallower than the other for most of the dive, ascends first and waits for the other, etc.), I'd suggest going with the most conservative of the ascents. There is a risk that doing the deep stops dictated by one computer will add the the length of shallow stops on another computer, so the ascent could get stretched out. Which means you better monitor your gas supplies closely, as unplanned decompression or just winging it could place a diver in a low gas situation.

Now, if I was ascending on a slope or wall with no current and good visibility, and was diving with known divers with good skills & experience, then having I would not object to having divers on stops 10' apart but maintaining visual contact. Any farther apart and emergency management gets really difficult. And gas allowing, I'd suggest that no diver leaves the water after clearing deco if other divers are still on deco.

 

[tursiops]

You have a lot of questions here; I'll try and make sure which questions I am referring to by quoting them one at a time.

I was taught to trust and follow my computer, to stick close to my buddy, and to ascend when the first person on the buddy team reaches a preset ascending pressure.

Excellent, good training.

What is the best protocol to use during the ascent when the two computers, from different brands (and presumable different decompression algorithms) between the two of us have significantly different safety stop recommendations, both in terms of time and depth?

Assuming enough gas, use the most conservative computer...i.e., the one that keeps you in the water the longest.

For example, one of us might have a deep stop at 50 ft for 1 min while the other may not have one at all.

This should be adjustable in your computer so it does not offer that deep stop, which is no longer a favored recommendation.

Another would be one of us having a shallow stop at 20 ft for 2 min while the other has one at 10 ft for 3 min.

This is highly unlikely, unless you are doing decompression profiles. "Safety Stops" are nominally at 15 ft, but actually anything from 20 to 10 ft is OK.

Do we both stop at the first indicated stop between the two of us for the longest indicated period of time between the two of us, and then ascend together until the next indicated stop, no matter which computer it is?

Yes

Could that possibly mess up our reserve gas amounts, or will the computers "catch up" and be relatively together as we go up?

The gas you have will depend on your breathing rate and your ascent profile. The person who hit reserve first, and thus caused you both to go up, will presumably have the lest gas when you finally get to the surface together.

What if one person is on air and the other person on nitrox?

All bets are off. If it is a deepish dive, then you will probably hit your reserve gas level first -- not your NDL -- and begin ascending. It won't matter if you are on air or Nitrox. The ascent profile and the amount of gas you use won't care what gas you are on. If it is not a deepish dive, but say around 60 ft max, you'll possibly hit your NDL before you hit your reserve gas limit, if on air, but not if you are on Nitrox. So the person on air will cause the dive to end.

 

[tursiops]

If you haven't planned your dive, and the dive team is in the situation where their computers are as dictating different ascent profiles (which can happen with the same computers & algorithms if one diver hangs 5 or 6 feet shallower than the other for most of the dive, ascends first and waits for the other, etc.), I'd suggest going with the most conservative of the ascents. There is a risk that doing the deep stops dictated by one computer will add the the length of shallow stops on another computer, so the ascent could get stretched out. Which means you better monitor your gas supplies closely, as unplanned decompression or just winging it could place a diver in a low gas situation.

Now, if I was ascending on a slope or wall with no current and good visibility, and was diving with known divers with good skills & experience, then having I would not object to having divers on stops 10' apart but maintaining visual contact. Any farther apart and emergency management gets really difficult. And gas allowing, I'd suggest that no diver leaves the water after clearing deco if other divers are still on deco.

The OP posted this in Basic Scuba, there is no decompression diving going on here.

 

[Foothills]

The OP posted this in Basic Scuba, there is no decompression diving going on here.

The OP references a computer dictated stop at 50'. That may not be decompression, but it sure sounds like it could be.