Shearwater Peregrin Surface Interval

[MauiBullfrog]

Aloha

I did a 60 ft 45 min boat dive yesterday and planned to do another 60 ft 45 min dive. With my Shearwater Peregrin, how do I check how long my surface interval should be? Sorry in advance for the noob question, but I've only had this computer for a few months with only 20 dives. This was the first time that I really needed to check it for my own sanity.

 

[BlueTrin]

I don’t have one but checked the online manual and saw this

https://www.shearwater.com/wp-content/uploads/2020/07/Peregrine_Manual-metric.pdf

 

[MauiBullfrog]

I read the manual and didn't understand it.

 

[BlueTrin]

I read the manual and didn't understand it.

I think it’s saying that you can use the NDL a planner after the first dive.

Change the interval time until it says that you can do the whole of the next dive in NDL.


For example put, next dive in 2 hours and then check if the NDL planner says that you can stay longer than your planner time at that depth?

 

[broncobowsher]

For the Shearwater you can't plan everything in advance. You can't calculate the second dive until you are back from the first.

Most people have a fixed service interval, not a fixed second dive plan. So you will have to work at it a little bit to get the data you are after. After the fist dive go to the NDL planner and put in different values for when the next dive will happen. Keep running the number up until you get a dive plan that exceeds your dive plan. Now you have the surface interval.

The typical use of the NDL planner is returning from your first dive, boat motors over to a new site. You know you have 90 minutes to the new site so you put that number in. Now you have the NDL limits for the second dive when the boat gets there. Since the boat has a schedule to keep, you either dive when they say you can dive, or you just sit on the boat. You don't get the luxury of telling the boat you are going to sit out another half hour so you can get an extra 10 minutes of bottom time. That puts the boat 40 minutes late and that messes with everyone's schedule. The boat, everyone on the boat, and the next group waiting on the boat.

But if you have the luxury of making your own schedule, it is just a matter of working scenerios on the NDL planner. And it will vary depending on if you are doing a perfect square profile, or if you average 30' with a minute at 60'. Calculations are based the actual profile you dived.