Calculating Surface Interval on Vyper

split0101 · Jun 25, 2006

I have read through the entire manual (a few times) and searched the forum, and I cant seem to figure out a good way of calculating your minimum surface interval.

For example if I did a 32 minute dive at 60' what would be my minimum service interval for me to dive to 60' again? I cant seem to figure this out on the Vytec. I used the dive plan simulator but it seems like a brute way to figure it out.

Any help would be greatly appreciated. Thanks!

SparticleBrane · Jun 25, 2006

Usually the normal recommendation is an hour SIT before you hop in again no matter what the depth.
...at least that's what I try to do, anyway.

split0101 · Jun 26, 2006

It just seems that it would be a useful feature to have on a dive computer. I figure I can calculate it via tables, but if a computer is supposed to replace those, then it should have the same functionality as a table and more.

Just a little confused why a computer would not provide this data for you....

PerroneFord · Jun 26, 2006

The computer's job is to keep you safe in the water. Not to tell you how long to stay out of it. There is no calculation for surface interval. In fact, I don't know any computer that will tell you "how long to stay out of the water", unless you violated deco. If you spend 10 minutes out of the water and jump in again, the computer will tell you that you don't have long!

However, this does illustrate one of the drawbacks of using a dive computer. It seems to lessen people's desire to plan dives. So stop worrying about your computer telling you your surface interval. Sit out an hour, or whatever, and go dive.

And to answer you question, on a 32 minute dive to 60ft, you could get out, drink some water, and jump back in. You just wouldn't be able to stay long. If I wanted to do another 32 minute dive, I'd wait an hour. Actually, I wouldn't, but that's just me.

Damselfish · Jun 26, 2006

split0101:
For example if I did a 32 minute dive at 60' what would be my minimum service interval for me to dive to 60' again? I cant seem to figure this out on the Vytec. I used the dive plan simulator but it seems like a brute way to figure it out.

sure, you can pretty much jump in the water anytime - but dive to 60' for how long?

I don't know about the Vytec, but the Gekko and Vyper have a PLAN mode (different from the simulator) - a simple scrolling display of how much NDL you would have at each depth in 10' increments, if you jumped in now - if it's not long enough, wait longer.

Really, unless you have some urgent reason to get back in the water why not just plan on at least 45-60min out, that's going to cover most rec situations pretty well. You will soon develop a sense of approx how much SI time you want for the diving you're doing, and a general sense is all you need. It's not like you want to plan to use down to the last minute of what the computer says you can do anyway. Think - I'm going to be up about an hour I think I'll head over to the hot dog stand. Not - I must stay up 35.9 minutes to have 46.3 minutes at 60'.

johnny_bravo · Jun 26, 2006

Seems to me that if you have time to do a proper SIT you should do at least an hour. If you are on a schedule similar to a liveaboard then you don't need to calculate a SIT because the computer will adjust your NDLs based on whatever SIT you did manage to complete.

IMHO I'm not sure if it's a worthy feature in a dive comp.

Cheers.

-J.-

split0101 · Jun 26, 2006

Hrmm I see what you guys are saying, thanks for all the responses.

The reason this question came up is when me and my buddies were out at Dutch this weekend, and we wanted to figure out how to get 3 dives in for the amount of time that we had that day. So using the RDP we could easily figure out the SI that we needed in between dives so we could plan our day more effectively.

The dive plan simulator is a decent tool on the Vytec, but it stinks that I have to keep on trying different SI offsets to determine the best SI to do my next dive (i.e. add my SI offset, set my max depth, and then read off the NDL time, repeat until you find the necessary SI to do the planned dive to the desired depth/length of time). Using a RDP I just figure out my two pressure groups, cross them on SI table and get the SI needed.

Dunno would seem like a nice feature to have.... I guess Im going to have to stick to planning out my dives with the RDP, and then just use the computer to keep track of things.....

PerroneFord · Jun 26, 2006

Easy fix.

Dive "best mix" and do proper stops on ascent, then your SI can be very short... Change tanks, warmup a bit, then go dive.

Diver Dennis · Jun 26, 2006

I don't know about the Viper but on my Mosquito and Cobra there is an Icon that appears on the left side and when that disappears you are good to go. If you go in before then, an exclamation Icon appears on the graph when you download.

pickens_46929 · Jun 26, 2006

The Vyper has a Simulator mode which takes into account any current deco obligation. See page 49 of the manual.

Calculating Surface Interval on Vyper

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split0101

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