Monday, May 18, 2015

Anti-inflammatory Andy

Windsurfers know that windsurfing is good for your health. Science is still playing catch-up with our knowledge. In one scientific study that was published just a few months ago, the researchers found that feeling awe lowered the amount of inflammatory cytokines (specifically, IL-6).

When my lovely wife read about this, she right away said "Andy is anti-inflammatory". She was talking about Andy Brandt, and thinking about the windsurf session we had a few days ago at Frisco Woods in Hatteras. After sailing for an hour, Nina stopped to take a few movies of Andy windsurfing. Here's one where Andy makes the Donkey Jibe look easy:
Here's another awe-inspiring old school freestyle move, the Free Willy:

We had been working on the light-wind version of the Free Willy just a few days earlier during the ABK camp. The light-wind Free Willy is not nearly as impressive, but it's still complicated enough to really confuse me. But with plenty of demonstrations and help from Andy, I finally go the move, Yes, only the light wind version, but it still filled me with pride and joy - two other emotion that will lower cytokines and inflammation.

I followed Andy around a bit that day, and he threw several perfect loops right in front of me. It got me motivated enough to try several times, although none of my tries even was close. But I'll count just getting myself to try as a big success. I had a bit more luck on my runs back in, where I worked on the Carve 360 with both feet in the straps. Early tries were close, but a bit wet:

After getting a couple of tips from Andy, I was able to carve through without getting wet:

Even though I understand the 360 pretty well, I would have never come up with the small adjustments that Andy Brandt suggested myself. As usual, they were spot-on, and following his suggestions made all the difference.
Funny enough, I ended up being better at the 360 in the straps than I am when I take the back foot out of the strap, even though the move is a bit harder in the straps. The likely reason? Bad muscle memory! When I take the back foot out of the strap, the entrance is almost identical to a jibe entry, and I have practiced bad ways to jibe for decades before my first ABK camp. The entry for the Carve 360 in the straps feels quite different, since you have to through your weight forward much more to compensate for the feet being further back. This setup I learned only last year, with immediate corrections from ABK instructors, so I never practiced the wrong way. It's so much easier to learn it correctly right away!

Of course, learning things correctly at ABK camps is one of the "secrets" why Nina has gotten so wicked good. She worked on getting into the straps in switch stance while planing in Hatteras, and was quite happy with her progress. Thanks to tips from ABK instructor Eric, she got quite comfortable getting into the straps switch while planing. She jibed out most of the time, but in her last run of the day, she ducked the sail switch for a Reverse Duck Jibe in the straps - a very cool move indeed. I don't have video of her doing this move, but Andy Brandt demonstrated it during the brief video session:

I'll leave you with a last video where Andy makes the Spock look easy:

Big thanks to Nina for taking the movies, and to all the ABK instructors for another fantastic ABK camp!

Tuesday, April 28, 2015

Harbor Cruise

Temperatures in the low 40s (6ÂșC). Light drizzle. Wind meter readings with lulls near 10 mph, and gusts of 35. Just a short time until we'll be in Hatteras, with temperatures in the 60s and 70s. So perhaps, some of you might question why I went windsurfing today.

The answer is simple: I wanted to sail on really flat water. One of my favorite spots for that is Barnstable Harbor. When the wind direction and tides line up just right, you can sail right next to the little gras islands, on "chop" that's maybe 1 or 2 inches tall. Today was one of the rare days where things looked like they's line up.  It helped that we had a neap tide, with barely 8 feet difference between low and high tide (compared to 12 feet during spring tides). The wind was predicted to drop, but it looked like there would be an hour with almost perfect conditions.

I was on the water at 10 am. The conditions did not look too exiting - not much wind at the launch; not many whitecaps on the water; and the water level was at least a foot higher than the tide charts predicted, because the strong wind in the early morning hours had pushed a lot of wind into the harbor. I had planned for some speed on small slalom gear, but conditions called for "comfort" gear - my Skate 110 and Matrix 6.0.

After a few minutes on the water, I realized that I had underestimated the wind. I was very nicely powered,  which means averages around 25 mph for the gear combo I was using.  I went to search for flat water, but most of the little islands in the harbor were still covered with water. So I cruised around a bit - here are the GPS tracks:
The distance from the left to the right is almost 4 km; the upwind distance close to 1 km. I stayed to the left at first, hoping that the islands would rise out of the water, but that did not happen as quickly as I wished. So I explored the other direction, and found an area where the water structure was a lot of fun: orderly chop that almost looked like waves, with very little cross chop, perfect to for little speed runs (the area on the right where the GPS tracks are yellow-greenish). Fun! I was quite surprised to find this area; at many other places in the harbor, the chop is more chaotic, sometimes even "voodoo chop".

Shortly thereafter, three things happened: the clouds finally started to move away; the wind picked up a notch, leaving me a bit overpowered; and the water level finally dropped low enough to let the grass islands emerged. So I went back to the van to get the 90 l slalom board, and sailed back over to the natural speed channels between the islands. Here is a short video that shows how flat the water is there:

By the time I made it to the slicks, the wind had dropped again. I had enough power to plane comfortably, but not enough for deep speed runs. So I am still waiting for the day where everything comes together for some real speed at Barnstable Harbor.  But what had started like a cold and dreary day had turned into a warm and sunny windsurf day with near-ideal conditions, so I'm not complaining!

Saturday, April 25, 2015

GPS Speedsurfing with your phone

Can you use your phone for GPS speedsurfing? Some GPS pioneers like Roo have said "absolutely!" for a few years already. With the recent production stop of the "gold standard" GT-31 GPS unit, this question has become more urgent. Several replacements are on the horizon, but none are available yet.

So Manfred Fuchs, author of the widely used program GPSResults, has developed an app for Android phones for speedsurfing called GPSLogIt. It not only logs GPS data to a file for later analysis, but also shows results for the last and best run of the session, and even tracks:
As a geeky wanna-be speedsurfer, I had to try it, so I bought a cheap Android phone on (RCA M1 4.0 for $67), installed the GPSLogIt trial, and tried it out as soon as we got some wind. For comparison, I used my GT-31. Results were quite encouraging - most numbers were very close, although the long distance numbers and the alpha 500 where a bit lower with the phone. With the current trial (1.3), I was not able to read the numbers while sailing, or even when taking short breaks on the beach. Part of the problem was that I double-bagged the phone, using a ziplock bag inside a waterproof armband. I had to take the phone out of the armband at a shady place to see all the numbers and tracks. Future versions of the software will probably have a screen with bigger numbers that can easily be read while sailing.

After the initial promising results, a more thorough test was warranted. I decided to compare the phone with GPSLogIt to five GPS units I have: two Locosys GT-31s, two Canmore GP-102s, and the Flysight GPS. Here's a table of the results (raw data are here):
The GT-31 and the Flysight data include accuracy estimates (SDOP), so I included the +/- numbers as shown by GPSResults (for 5x10 seconds, I used a "typical" number for the 10-second runs).

All speed results obtained with the Android phone and GPSLogIt are within 0.6 knots of the numbers the other units gave. The 5x10 second numbers, which are often viewed as the most important top speed numbers, are within 0.1 knots, and well within the accuracy range of the GT-31 and Flysight units. However, the numbers for the nautical mile and especially alpha 500 are significantly lower. A close look at the doppler speed graph and the tracks provides some clues. Let's start with a large-scale view:
Mostly, the data for all 6 units are very close, but there are a few areas in the speed graph where the phone data drop below the other units. Here is a closeup:

There are several short areas in the track where the phone speed is artificially low; this explains why the long distance numbers are a bit lower than for the other units. It is fortunate that the error is on the low side - from the view of a competition, GPS units that understate true speed are acceptable, but units that overstate speed are not.

For the alpha, a look at the tracks when I drove around in circles is illuminating:
Blue: GT-31; red: Flysight; purple: phone & GPSLogIt
The tracks for the Flysight, which uses an UBX GPS chip and records at 5 Hz, is most accurate. The GT-31 tracks are close, but the phone tracks show some obvious deviations. Clearly, the phone had the most problems to accurately track direction changes. This may well be due to processing limitations in the GPS chip firmware that are related to limits on how much battery the GPS chip can drain. As it is, the accuracy is certainly sufficient for the common uses - navigation and photo tagging.

Overall, the GPS accuracy of the phone I used was certainly acceptable, albeit not "perfect". Other phones may use different GPS chips and give different results, but several others have also reported decent accuracy with other phones. Nice to have another option for tracking your windsurfing sessions - and one that's less than $100, even if you buy a phone just for this purpose!

Saturday, April 18, 2015

Three Times Eleven Is Enough

It's getting warm. To warm to stay at home even if the wind is light.
I took the pretty cat out for a ride today. Amazing how the GoPro can make it look small!

A couple of days ago, the lovely Nina joined me for a light wind session. She took the Mistral Pandera and a 5.3 m sail, and had tons of fun in 15 mph wind. I took my BIC wind SUP because I wanted to test my new fin:
It's small - 11 cm, to be exact. When I saw it on the Black Project Fins web site, I just had to have it. Just imagine - put it into the SUP, step a little bit forward, and with a little help from the rocker, I can sail all the way to shore in Hatteras! No more walking!

I figured it would be big enough. When Caesar was here last fall, he never used a fin in light wind. I'm no Caesar. I can sail the SUP without a fin, but need to concentrate so much that I can't do much else. But I have used a 15 cm fin without a problem, so 11 cm should be fine, right?

It took a number of back-and-forth emails to convince Chris at Black Project that I had not lost my mind, but eventually, he mailed me the fin. When I tried it two days ago, I learned stuff. For example, I learned how easy it is to turn a 10 foot 6 board by scissoring your legs when you have a really small fin. It worked, and my previously slow-turning SUP now turned like Nina's Nova.

However, I move a bit slower than Nina, so it turned a tad fast for my taste. Sailing leeside (backwinded) or in switch stance also required just a bit too much attention - not enough pressure on the front foot, and the board turned into the wind.

Then I realized what the problem was: the fin was not too small - it was lonely! There were two unused fin boxes in the board. As soon as I put the two little side fins in there, everything was perfect! All three fins are about the same size, and worked just about 3 times as well as one of them. Surprise! (NOT!!). I have mostly used the board with just one 26 cm center fin in light winds; but 3 times 11 is more than 26! The total area may be a bit smaller, but the board tracked beautifully, even when sailing switch or leeside. Whatever the numbers are - three times eleven is plenty.