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Mar 01

GPS data while wakesurfing

As we mentioned in yesterday’s post we have a GPS data logger for wakesurfing set to be delivered this week and it will allow us to record some information on an SD card, like in your digi-cam. The data logger that we are using is pretty good but it’s not NASA grade or anything like that. It will log information in 1 second intervals. We’ve seen GPS data loggers designed for race cars that can log data upto 10 times per second! At 150 mph, that no doubt is very useful. Interestingly enough those devices aren’t water resistant and have to be plugged into a computer. Nice for THAT environment, but not so much for us!

We can calculate a number of things once we have some basic information. If we have a set interval that is known, like we mentioned every 1 second then changes between the data “sentences” can be used to calculate things like acceleration and decceleration…or really we guess it’s just negative acceleration.

Let’s work through a quick example of (positive) acceleration in wakesurfing. If we have a few data sentences that show the rider at 11 mph, but then in the next sentence the riders speed is 11.5 and then in the next sentence it’s 12.3 we know that over the course of 2 seconds the riders speed went from 11 mph to 12.3 mph, or an increase of 1.3 mph / 2 sec. We seldom discuss speed changes in terms of how fast per every 2 seconds :) so we can change it to a speed change per second or even per minute or even hour. But if we solve that ratio for the lowest common denominator it is something like .65 mph / sec. Now we don’t know if that is an accurate number, we just threw some figures out there, but you get the idea.

Acceleration is the change in velocity divided by the change in time.

Now you most likely are sitting there thinking so who in the hell cares! Well, you should for a few reasons. One reason is that your ability to accelerate on a wakesurf board will help you do more and better tricks. It will also help you recover from awful situations. BUT it will also eliminate the dreaded “the best board in the world is _______ ” insert whatever is being hyped at the moment.

Right? Have you ever heard the advertising for sports cars where the acceleration is 0 to 60 in 2.6 seconds. That’s pin you to the seat fast, isn’t it? Now is that more credible than, say – the humpgrumper Mark XII is the fastest board ever. You have to be as tired as we are of all those nonsensical claims from the humpgrumper folks. C’mon humpgrumpers! Stop feeding us crap!

If we can develop a systematic methodology that can be replicated and doesn’t rely on the subjective opinion of folks trying to sell you something, then CONSUMERS benefit. Now that isn’t to say that everyone should rush out to by the fastest accelerating wakesurf board. It may just be too quick for your personal tastes, but maybe the .32 mph / sec accelerating board is just perfect! See? Tangible, emperical and measurable evidence. Sorry humpgrumpers, we know you’ve thrived on all that puffery, but we think it’s time for a change.

We’d love to not have to rely on intentionally misleading camera angles and lens, or the intentionally misleading statements of folks try to sell you stuff. Lets start developing some tangible, emperical and reproducible data that folks can use to make informed buying decisions.

The one thing that we can’t emphasize enough is that individual riders will want different things from their wakesurf board. THAT is perfectly fine. You may not LIKE a car that accelerates from 0 to 60 in 2.6 seconds, right? Say for example, as a first car for little Timmy “crash” Spinozivic. But it doesn’t detract from that fact that someone might want that.

We can also calculate the effective length of the pocket on wakesurf boat wakes using the data from our GPS data logger while wakesurfing. BUT that would require two GPS Data Loggers. One at the transom and then one on the rider at the very back of the wake. Does that make sense? The data we would be getting is actually of a rider moving, so who knows what the fixed distance is from the boat. But if we position a GPS at the transom and record that point and then do the same thing at the back of the wake on a rider, viola we have the distance or length of the pocket. That would certainly be helpful wouldn’t it? We get all manner of distorted photos and claims from people that a pocket is so long it’s in a separate zip code. Whatever. We could also do it with a tape measure, but the GPS stuff works pretty well and easily also.

Lastly, as a rider is pumping across the face of a wake, we’ll be able to determine, directly, the speed of the rider. Fast is good and if we were comparing two shapes, we could determine which was the fastest, OR maybe we have a magic board that we want to duplicate, we could determine it’s ability to accelerate and even it’s typical maximum speed and the develop a board that comes close to those two attributes.

Let’s also look at a really complicated scenario. Let’s assume that the wake we are working with has an optimum spot on the lip to launch an aerial from. Too far forward and the lip is rounded and soft, too far back and there isn’t enough transition, so our rider is looking to launch from that specific location. Now Let’s say that with one pump of the board the rider can’t go the very back of the wake, he has to start his launch from 4 feet in front of it, BUT two pumps can’t quite be squeezed in, in the distance from the launch point to the back of the wake. Like this:

Concave Deck skimmer 256

If we knew how much distance a rider could cover in one pump before a degredation in speed, there is a close approximation that could be made right up front, OR possiby it’s time to pull out a board that can squeeze two pumps into that distance, because it doesn’t travel as far per pump.

No, really! If we can get some accurate readings, we have the ability to measure and associate that data with specific board attributes. Science, and Math, rock! Now we want to add that we aren’t quite sure how accurate these readings will be. That could just be a matter of getting a better GPS data logger or maybe none of them can give the accuracy we really need. We’ll keep you posted of what we find!

Thanks so much for following along, we appreciate it.

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