Friday, May 31, 2019

GPS Speedreader

In recent years, I had gotten a bit frustrated with the existing GPS analysis software. For some of the GPS prototype testing, there were too many bugs that just made the life hard. Furthermore, the "older" software that was developed almost 20 years ago can be painfully slow when looking at new, higher-rate GPS data from the Locosys GW60 or the Motion GPS.

So I wrote my own, and I'm releasing it to the public today. It's free software, supplied without any warranties - but if you want to send me "beer money" to support the further development, that's great! There's a donation button on the  GPS Speedreader Help page for that. 

This post will show a few screen shots, and point out a few useful functions in GPS Speedreader. Here's the main window:
The session shown is my recent 12-hour, 306 km session where Nina grabbed the #1 spot in the GPSTC women's ranking for distance. It's a large file, and trying to see the 1-hour results in GPS Results on my Windows computer took more than 5 minutes. In GPS Speedreader, the file opens in less than half a minute, which includes calculating the results for all GPS Team Challenge categories.

The main window is divided in a left side that shows the GPS points on the top, and the category results on the bottom. The right side can show up to three graphs: tracks on top, doppler speeds in the middle, and error estimates on the bottom. Clicking anywhere will select the point or region; here, I have selected the top 2-second speed. You can zoom in using the mouse scroll wheel or trackpad gestures:
There are a few different dialogs where you can choose what you see, what your time zone is, and so on. Here are the general preferences:
GPS Speedreader was developed specifically with the GPS Team Challenge in mind, and with a lot of feedback from GPSTC advisors. It's pretty easy to post session results to the GPSTC - just select "View results in browser" from the "File" menu. This will open up a browser page with the results:
At the bottom of the results, there's a button. Click on it, and a session page on GPSTC will open, with all the numbers filled in for you. You just have to add a comment and press the "Post" button. 

GPS Speedreader does not have all the functions that other programs have. For example, background images are not supported, and there is no "Jibe analysis" like in GPS Action Replay Pro. I will probably add some more features over time, based on feedback on the Seabreeze GPS forum. But with summer starting here, I'll hopefully spend more time on the water soon!

A couple of things are unique to GPS Speedreader, though, and deserve mentioning. One is the "Compare files" function which I wrote to make comparing different GPS units easy. You can open two (or more) GPS files from the same session, and Speedreader will compare the results in all GPSTC categories. It will even compare the error ranges, and flag any discrepancies with a yellow, red, or orange background. If you want to have a close look at the data, you can pick which columns are shown in the data table:
But that may be more for geeks. Perhaps a thing that's more useful for many is that Speedreader supports opening files by drag and drop. On Mac and Windows, you can drop GPS files onto the application icon; on Mac, Windows, and Linux, you can drop files onto the main window.

To read more about GPS Speedreader, check the online help at To download the program and start playing with it, visit

Tuesday, May 21, 2019

Oops She Did It Again

Seven years ago, Nina briefly held the #1 spot in the women's distance ranking on the GPS Team Challenge - the unofficial women's distance world record for windsurfing. Her distance of 202.79 km was beaten a few month later by  speedfalconster, who sailed 207.55 km - barely 3 miles more. Her record latest until 2016, when the Australian speedsurfer Cheryl sailed 226 km. Cheryl sailed at Albany, a wonderfully flat spot that is in my top-3 list of the best windsurfing spots in the world.

Nina tried to get the record back a few months later during our regular spring trip to Hatteras. During the attempt, she also competed in the first Hatteras long distance race, where she won the Women's Open division. Alas, the waiting for the start of the two races ended up costing her the distance record when the wind died in the afternoon, just three kilometers shy of Cheryl's record. Another couple of months later, speedfalconster sailed 248 km to be back on top.

Nina had talked about another distance attempt a few times before, although she'd rather keep working on freestyle tricks (unlike me, she considers sailing back and forth for hours as "boring"). However, we never quite got the right conditions .. until this forecast came along:
Planing winds all day, and 14 hours between sunrise and sunset! I was definitely doing distance! So Nina decided to play along and forget about freestyle for a day.

The setup was good, but not quite perfect. One issue were the relatively weak winds in the morning; a bigger issue were the strong winds in the afternoon, and the southwesterly direction which means high water levels and more chop. Unlike earlier distance attempts, we did not have a house right on the Sound, so some of the daylight time would be wasted rigging and derigging. Perhaps even worse was that our fitness levels were still just mediocre, after having fought several severe colds since returning from Oz.

But when we got up at 5 am Monday morning, the local meters showed 18 mph wind - it was a go! We left the house just as the sun was coming up, and started sailing at 7 am. Believing that the predicted forecast would happen, we both rigged a bit small - 6.3 and 7.0. That meant some pumping  from time to time to get going, and slim chances to plane through jibes.

We sailed for about 5 hours, knocking off the first 150 km with relative ease. During lunch break, the wind dropped, shifted, and then picked up. Here's the wind graph from the "KHK Resort" meter for the day:
I downsized from 112/7.0 to 99/6.3 by grabbing Nina's gear. However, the wind in the high 20s meant lots of chop, and I found myself blowing jibes and not feeling comfortable anymore. What's the point of sailing for 12 hours if you're not having fun? I replaced the slalom board with my Tabou 3S96, which handles chops a lot better. I kept he cambered race sail (Loft RacingBlade 6.3), but the combo worked surprisingly well, and I enjoyed the next few hours of sailing. Nina switched to her freestyle gear - Fanatic Skate 86 and Idol 4.5, which she often sails in crazy conditions. We sailed these combos until we both had sailed about 250 km - Nina had her World Record back! But she was not yet tired and wanted to go for another 60 km. I hoped to add another 100 km, but by then, the wind and chop had increased to levels where our sails where just too big. Nina downsized her Idol to 4.0, and I switched to a 4.7 wave sail.

Then, things did not go quite as planned. An hour later, Nina had to stop because her hernia was acting up. Her total distance for the day was 277 km, about 30 km above the previous record. Nice!

I never got comfortable with the 4.7 wave sail, going between underpowered to overpowered in every run. Maybe the difference from the super-stable race sail was too much; maybe the chop had gotten too high; or maybe I was just getting tired, but I was getting slower, and spent a lot more energy than before. As the sun dipped lower on the horizon, I also saw a lot more wild life - including jumping, spear-like fish that are know to occasionally pierce windsurfers ankles. So I decided to stop an hour before the sun went down, so we'd be able to put all the gear back into the van while it was still light. Here are my GPS tracks for the day (click on the image for a larger version):
These are Nina's tracks:
Here's the women's ranking for distance on the GPS Team Challenge:
Today, the wind turned to NE, which means much shallower and flatter water. We went for a quick sail, and it was lovely - if only we would have had such flat water yesterday! But NE wind here rarely lasts all day - today, it lasted just a few hours. Maybe we have to go back to Australia for the next distance attempt :-).

Monday, May 13, 2019

Foiling in Hatteras

We had not planned to go to Hatteras this spring, but after the last cold water swim session, we made a last-minute decision to drive down for the ABK camp. We got a windy day on the Sunday before camp (3.4 for Nina, overpowered 5.0 for me) that showed us how out of shape we were. The camp was fun, as usual, although I spend most of the time trying to remember how to do things I had done before, with varying success. For me, the highlight of the ABK camp was the windsurf foiling on the last day. The wind increased to about 18 mph in the afternoon, which made getting onto the foil very easy - but controlling the power once up in the air was a very different story! I had only foiled a handful of times before, and I probably doubled my air time in this session. Fun!

Today was another day with warm SW winds. Meter readings were around 20 mph when we rigged, so I thought I'd have plenty of power on my 6.0/Skate 110/WeedDemon 29 combo. But of course, the wind dropped a couple of knots as we got out, and I only planed in the gusts. Perfect for foiling! The friendly ABK folks had left 4 foils out on the lawn at Barton's, and Tom and Brendon confirmed that it was ok to take my favorite combo out - a Slingshot Flyer with the 84 cm Infinity wing. Since the water depth here is limited, the mast was a bit shorter - 28 or 30 inches.

Once I reached the deep water and got on, the board wanted to get out of the water right away - it seemed the wind had increased by 5 knots! I made a bit of progress keeping the board flying a foot above the water, and had a bunch of fun crashes when the short periods of control ended. My favorite time was going upwind on the foil, but with the board just barely out of the water, so that the skinny nose of the flyer would still touch the chop. This ended up being my first foil session where I tried to sail at different angles to the wind. Upwind was reasonably easy, but any little bit of downwind angle made things very interesting and "lively". More fun crashes! At one point, I must have placed my foot a bit wrong, and the board/foil kept carving downwind until I noticed that I had gone past six o'clock. A quick sail flip, and I had completed my first jibe on a foil! Well, only the start was up on the foil, the end was with the board in the water, but it was fun. I even managed to do a second jibe later in the session, this one on purpose.

For this session, I wore a GPS, which showed a few interesting things:
The first thing to notice is the low speed. My fastest 2 second average was 13.7 knots - about 10 knots slower than an average session on my freestyle gear, and less than half of the speed of a light wind slalom session. But it sure felt plenty fast to me! Interestingly, my old Mistral Equipe raceboard probably would have reached slightly faster speeds with the same sail today (and 20 knots with a larger sail). I love sailing old longboards because the feeling of railing up on the daggerboard in intermediate winds is really cool. This is a bit similar to foiling - but the foil adds a completely new sensation with the foil push that's directed fully upward, without the heeling momentum from the daggerboard. Once the foil pushes the board completely out of the water and everything goes completely quiet, it's a feeling unlike any other on a windsurf board. When that happens, I need to concentrate 100% on keeping the board at an even flight height - I automatically get pushed into "the zone". Well, at least for a few seconds until everything comes down again, and I may end up getting thrown into the water.

The GPS tracks also show that many of the "foil runs" were very short. Perhaps 2 out of 3 times, I'd still be on the board after a touchdown, but the board had lost most of its speed. One out of three times was a dismount - sometimes getting thrown off by a bucking board, sometimes jumping off to make sure I'd stay clear of the foil after the exit. Fortunately, the water was warm, and the depth was perfect - deep enough for foiling, but shallow enough to stand.

Another interesting thing the tracks show is that my angles to or off the wind were not nearly as deep as I thought. In fact, the sailing was closer to typical shortboard sailing angles, which are mostly just going back and forth across the wind, than to raceboard tracks, which often include right angles. But then, I'm still a (slow-learning) beginner on the foil :-).

The longest steady run was about 750 meters over 2.5 minutes, with an average speed just above 10 knots. I probably was "semi-foiling" for the first half the run, with the foil pushing the board just almost out of the water. The second half of the run is at a lesser angle, so the board probably was completely above the water most of the time, with just a few gentle touch-downs every now and then. Amazing how much fun you can have at 10 knots, going slower than the wind speed! Big thanks to ABK Boardsports, Andy, Tom, Brendon, and Slingshot foils for making this possible.