Source Data looks like this:

Dude, nice geekery there.

Question, you note near the end that the elevation gets flatter as you progress down the line, I can see that as the big drop happens but then you'd expect it to go up and down. Do you think the foil makes this up and down less necessary as it's working inside the wave and sort of being pushed as opposed to sliding down, or what? Interesting finding there.

Cooler still is an Elevation assessment on a big wave.

I went back and opened up data on this wave from Nov 12th, 2016.  1 year ago last Saturday at Mavericks. 

Waves isolated at Mavericks have shown a stepped nature.  Drop, come up a little bit, and then drop again. 

This data suggests I descended 17 feet on the initial drop, shown in the picture below.  I then ascended 4 feet and then fell another 7 feet before kicking off the wave to the south. 

A full drop from Peak to Crest would likely result in getting hammered by the wave.  Best practice might suggest leaving a healthy trough below your feet and progressing down the line to survive until the next wave. 

Hi Guys, happy thanksgiving.  Reading this thread is a bit unsettling.  Beasho, I know from reading you're posts that you are basically a shoulder hopper at a Mavericks.  Good for you.  Most of us on this site would not go there.  You are a brave man.  When you get into you're Wave count mode and you're total Drop feet for the year, you have lost me.  I mean really, is this all you do?  Please don't take this wrong way.  It's kind of in jest, but really.

Some people just have to know. I'm not wired like Beasho, I get bored with data. But I understand the passion for it, and the truth is, that it makes the world go round. It used to be that bullshit ruled, but now it's data.

My quirk is that I take on insane projects that have no practical purpose. Different strokes, and yeah, beats the shit out of watching TV or not knowing how anything works. Keeps us off the street and out of mischief--mostly.

Long period waves certainly continue to jack as they peak, and away from the crumbling crest (and sometimes even at the crest, like shipstern), they continue to grow, which is one reason they eventually break down the line (the other reason is that the ocean floor may continue to slope shallower). All that energy behind the wave is moving faster than the energy in front, so the water stacks. Perhaps variations in the ocean floor changing the rate of growth of the face would account for actually ascending when you still feel like you're descending (and relative to the plane of the wave, you actually are descending).

The math for this stuff is only heuristic. Interesting to me how elusive first principle explanations for water wave motion actually are. No lesser light than Feynman took a good swing at the energy transfer between wind and water making waves and gave up on it after nearly a year of work. The actual mechanism and some associated math that actually works for transferring energy to a surfboard are equally impenetrable. It's easy to derive how much energy is transferred and to backfill formulas that describe the phenomena observed, but as usual, the deeper you go, the muddier it gets. In serious texts, the authors start tossing away terms of equations that are problematic--a certain indicator that they are getting lost.

"Do you know what the horizontal and vertical error specifications for the GPS are for your specific device?  The altitude measurements by non military GPS are  usually quite inaccurate....."

Have not found GPS elevation data to be consistent enough for me to trust.  Just paddle around on flat and see what you get for your device.  Or walk or ride your bike on a level street to check for error.

https://support.garmin.com/faqSearch/en-GB/faq/content/QPc5x3ZFUv1QyoxITW2vZ6

https://www.singletracks.com/blog/gps/gps-elevation-accuracy-test-smartphone-apps-vs-dedicated-gps/

http://gpsinformation.net/main/altitude.htm