• Welcome to the DeeperBlue.com Forums, the largest online community dedicated to Freediving, Scuba Diving and Spearfishing. To gain full access to the DeeperBlue.com Forums you must register for a free account. As a registered member you will be able to:

    • Join over 44,280+ fellow diving enthusiasts from around the world on this forum
    • Participate in and browse from over 516,210+ posts.
    • Communicate privately with other divers from around the world.
    • Post your own photos or view from 7,441+ user submitted images.
    • All this and much more...

    You can gain access to all this absolutely free when you register for an account, so sign up today!

How to compare dives?

Thread Status: Hello , There was no answer in this thread for more than 60 days.
It can take a long time to get an up-to-date response or contact with relevant users.


New Member
Sep 4, 2001
I'm playing around with the divelog from my suunto stinger.
Each record in this logfile contains Average Depth for that dive and the total time of the dive.

For the fun of it, I'm comparing dives based on the product of these 2 numbers. Now I'm wondering of this is a valid way of determining which dive was 'tougher'.

Is 60 seconds at an average depth of 10 meters (60 * 10 = 600)
a better achievement than 30 second dive with 15 meters average (30 * 15 = 450)?

Any thoughts on this?
Still playing around with the dive profiles
Your remark on the derivative of the profile made me think about fitting a theoretical curve.
Did you ever do something like that? Most of my dives look pretty similar, almost parabolic shaped. Would be interesting to find out your 'personal dive profile' parameters.
The dive speed & the area under the profile would follow directly from such a formula .
I just found a great tool Advanced Grapher that could do a best fit of one of my profiles. The best one is 9th order polynomial. I settled for a 5th order.

Turns out that my dive followed this formula (x being time in seconds and y the depth in meters):

y= 8.6 *10^-8 * x^5 - 1.9 * 10^-5 * x^4 + 1.5 * 10^-3 * x^3 - 4.1 * 10^-2 * x^2 - 0.19 *x -0.93

Better to see the graphs themselves .

Interesting to see the almost constant ascent rate in the 50-70 second interval and then the sudden acceleration of it towards the end of the dive :duh
Last edited:
I made an ASCII export from the Dive Manager software. This will give you 4 CSV files. For example calling the export 'divelog' results in:

divelog.csv -> most of the information per dive
divelog$DGE.csv -> the gear you added for a dive
divelog$NOT.csv -> the notes you added for a dive
divelog$PRO.csv -> dive profiles!!!

this last one contains rows with:
dive number, measurement number, depth, a lot of bogus ....

I extracted the profile for this graph from this last file copied the numbers into the grapher program and let it fit.
A lot of my profiles look like a steep descent parabola on the left and a broader (slow ascent) parabola glued to it on the right.

I was just rethinking the derivative. In it's simplest form it should be a straight line going through y=0 at your max depth point. Or 2 straight lines with a slightly different angle that connect in that point. The graph from this fit might be too fancy due to the 5th order polynomial coming out of the fit.
DeeperBlue.com - The Worlds Largest Community Dedicated To Freediving, Scuba Diving and Spearfishing


ISSN 1469-865X | Copyright © 1996 - 2024 deeperblue.net limited.

DeeperBlue.com is the World's Largest Community dedicated to Freediving, Scuba Diving, Ocean Advocacy and Diving Travel.

We've been dedicated to bringing you the freshest news, features and discussions from around the underwater world since 1996.