Thursday, November 29, 2018

That's Why

Some of my readers might have been wondering why I want to go to Australia to speedsail in very weedy water. Well, it was windy in Western Australia yesterday, and the speedsurfers around Perth made a very good argument for visiting! Some highlights:

  • 26 speedsurfers from 3 teams posting sessions on GPSTC
  • 19 new personal bests
  • Top speed 41.6 knots
  • 19 sailors posting 2 second top speeds above 34 knots (9 above 36 knots, 3 above 40)
  • A 38.7 knot nautical mile, with 3 posts above 35 knots 
  • 8 alpha 500s above 24 knots, including 2 above 26 knots
Conditions must have been fantastic - 5 of the windsurfers sailed more than 100 km. The sail sizes used were mostly in the 5.8 - 7.0 meter range, with 6.2 m the most common size. Since most of these guys are "recreational" speedsurfers, it's safe to assume the wind was strong, but not extreme. The closest wind meter I could find (in Rockingham) showed wind averages of about 30 knots:
Most of this happened in Mandurah Bay, about 60 km south of Perth, WA. Here's another video from this spot:


Tuesday, November 27, 2018

The Shaking Is Real

I got a few runs today at the Kennedy Slicks before the wind turned too westerly. Here are GPS speeds from on run:
The red line shows the acceleration (the difference in speed from point to point). It's noisy! It all that shaking real? Well, I might have given the answer away in the title, but I owe you an explanation.

First the parts of the graph: it starts with a short break, then some walking into the water, some slogging, sailing through choppy water at about 22 knots, then in smooth water right next to the pier at 28-30 knots. A jibe is next, then back to the the start, pinching upwind. Note that the biggest acceleration changes are in the choppy approach to the wall.

I had my phone right below the GPS in an armband, and recording the acceleration data (at 10 Hz, just like the speed above):
This is a bit more confusing since we measure the three dimensions separately, and the phone changes orientation. But note that the overall pattern is quite similar to that from the GPS! Here are a couple of zooms:

I also had a GPS on the head, here's a comparison of the jibe region:
Note that we get a larger acceleration with the GPS on the arm - that right when I flipped the sail! The arm went forward first, reducing measured speed, and then back, increasing measure speed. The GPS picked that up nicely! The accelerometer peak at this region confirms that this is a real movement.
The head GPS has a smaller acceleration at this spot, but it's still above the 8 m/s2 filter threshold in GPSResults. With default settings, GPSResults would not give me an alpha for this run! Silly. If we measure at higher resolution, filters need to be adjusted accordingly!



Friday, November 23, 2018

Lanes Through Weeds

Weeds and speedsurfing? Yes! Check this video from Fangy's Weed Farm down under:


Only a few more weeks, and we'll be there, desperately trying to find the lanes. The promise of 37 knots in 20-25 knots of wind certainly makes spending a day or two on a plane worthwhile!

Sunday, November 18, 2018

Accelerometer Fun

If the image above makes you curious, keep reading. Otherwise, stop now! This is a slightly geeky and (for most windsurfers) irrelevant post.

In recent discussions about GPS prototypes, some issues about acceleration arose. Current GPS analysis software has "acceleration filters" that aim to automatically identify artifacts by looking at the speed change from one point to the next. We know how fast we usually accelerate on windsurfers - something like 1-2 knots per second is typical. Much more than that, and it's probably an artifact (or perhaps a humongous catapult). Points with high acceleration are excluded from further analysis.

For 1 Hz data from the good old GT-31 GPS units, a threshold of 4 meters per second squared (4 m/s2) worked well. For the newer 5 Hz units, GPSResults automatically raises the threshold to 8 m/s2.  However, when analyzing 10 Hz data from prototype GPS units, we often noted discrepancies to 5 Hz units, especially in the nautical mile runs, and often tracked the acceleration filter down as the culprit: if a single data point in the middle of a nautical mile run had an acceleration above 8.0 m/s2, then the entire run would go missing, since runs cannot contain filtered points in GPSResults (with the default settings).

Why would 10 Hz data have more "problem points" with a high acceleration? Here are two possible causes:

  1. Noise and simple math: acceleration is speed difference divided by time. If we go from 5 Hz to 10 Hz, the   number we use for time goes down from 200 ms to 100 ms. To illustrate this, let's assume that we have a "noise peak" of 2 knots (1 m/s) between two points. At 5 Hz, this gives at acceleration of 5 m/s2; at 10 Hz, we get an acceleration of 10 m/s2 which would trigger the filter.
  2. Actual movement of the GPS: we have seen above that a speed difference of just 1 m/s is enough to trigger the filter if we measure at 10 Hz. That corresponds to just 10 cm (4 inches) of (extra) movement. With a GPS on top of a helmet, just having the head move suddenly when hitting a piece of chop could cause such an extra movement; similarly, the wrist might move when the rig is hit by a big gust.
Which one of these is the culprit? Well, if it's an actual movement, we should be able to measure it, right? How about using an accelerometer? Every smart phone has one, and there are plenty of apps on Google Play to read it and store the acceleration numbers. Unfortunately, that raises the next question - how good are the accelerometers in smart phones? 

Fortunately, the cold temperatures and lack of wind gave me time to play around a bit to get some answers. I'll switch to a question-and-answer format for the rest of the post to describe what I did.

Q: What were the questions?
  1. How does the accuracy of a smartphone accelerometer compare to the acceleration calculated from GPS speeds?
  2. Can we use a smartphone accelerometer to differentiate between random noise and actual movements in GPS data?
Q: What's the setup for the experiment to get answers?
The basic idea was to use a phone and a GPS in a controlled setting with regular acceleration changes, and to compare the data from the two devices. I used a pendulum setup: as the pendulum goes back and forth, it goes from zero speed to maximum speed at the center, and back to zero speed at the top on the other side. The changes are gradual and smooth, basically creating sinus curves for both speed and acceleration. Here's a picture of the setup I used:
It's a dustpan with a stick, and a plastic case to hold an Android phone (Samsung Galaxy J1) and a u-blox 8 / Openlog GPS prototype. The case is attached by velcro. I stepped out onto the balcony, held the stick at the top, and let everything swing back and forth, doing roughly a half circle (180 degrees) with every swing.

Q: How did you log the data?
The GPS was set to log at 10 Hz (NAV-PVT only), after letting it warm up for 20-30 minutes. On the Android phone, I installed the app "Sensor Record", and logged Accelerometer data at 10 Hz (100 ms delay). 

Q: How did you analyze the data?
I used software I wrote to read the GPS files, select the regions I wanted to use, and copy and paste the data into LibreOffice. I also copied and pasted the accelerometer data (from the .csv files the app made), and calculated a measure of total acceleration as:
a = sqrt(x*x + y*y + z*z) -9.81
where x, y, and z were the sensor reading for the three dimension, and 9.81 is the standard gravity (which the z sensor shows without movement if the phone is lying flat).
For the GPS data, acceleration was calculated as the difference in doppler speed to the previous point, and converted to m/s2. 
To align the data from the two devices, I used the time stamps as a rough start, then created a line graph, and deleted cells in one column to create the exact alignment.

Q: What are the results?
Let's start with a graph that shows the measured GPS speed and acceleration:
So this is roughly as expected, except that it's a bit noisy. All the movements and speeds were about the same, so all the peaks should be more similar than they are. The next graph compares the acceleration from the GPS (in red) to the acceleration from the phone accelerometer (in blue):

The acceleration measured by the phone was much smoother, and much closer to the actual motion of the pendulum (for a better look, check the first picture in this post, which is a plot of only the first section in this graph). So that's quite promising!

Basic physics tells us that the changes in speed for a pendulum should be smooth and continuous, generating a sinus curve. Therefore, changes in acceleration should also be smooth (remember that the derivate of a sinus curve still looks like a sinus curve, just offset a bit?). So let's look at the changes in measured acceleration in the accelerometer data:

The solid curve shows the changes in acceleration; the broken line shows the acceleration for comparison. You may notice that lines going down are a bit steeper than the lines going up - that's because I pushed the pendulum a bit from the right to the left so that the height would remain the same for every swing. 

Now let's look at the changes in acceleration in the GPS data - we'll just add a read line to the graph:
This is much more chaotic! All the extra spikes in the data are from random errors in the GPS speeds. They are just much easier to see in this graph (which is typical for second derivative graphs).

Q: What are the answers to the initial questions?
  1. How does the accuracy of a smartphone accelerometer compare to the acceleration calculated from GPS speeds? The smartphone accelerometer is much more accurate (at least in this test). That's no big surprise, since it was designed to measure acceleration, while GPS units are primarily designed to determine location.
  2. Can we use a smartphone accelerometer to differentiate between random noise and actual movements in GPS data? Yes, it seems that the smartphone accelerometer can be a useful tool to answer this question. Note that in this experiment, the GPS was a bit more challenged than when windsurfing, because it was done right next to a house, and because the GPS antenna changed its orientation to the sky by 180 degrees during each run, ending up sideways to the sky. 
Q: Why can't we just use accelerometers to calculate speed?
If the acceleration numbers are so accurate, it would seem logical that simply integrating them should give us speed numbers - would they not also be accurate? Only in theory (and perhaps in the absence of gravity .. but that's also a theoretical scenario). In practice and in the presence of gravity, we would have to know the exact orientation of the sensors at all times to calculate accurate speeds. Any small errors would quickly accumulate. According to a device manufacturer, even relatively small "angle error" of two degrees would lead to a velocity error of almost 2 knots within 10 seconds - much worse than what we can get from a GPS.

If you take a close look at the graphs above, you can see some obvious indications of the "angle problem". The graphs from the accelerometer acceleration has much higher positive than negative values. If we'd integrate that to get the final speed, we'd end up with a final speed in the 100 knot range! 

That is a result of the way I treated earth's gravity in the calculations, subtracting it after combining the three dimensions. Theoretically, gravity should be subtracted from the z-dimension before adding the acceleration vectors to calculate net acceleration. That's easy enough if the phone orientation is (a) known and (b) constant. But in the experiment above, the phone changed orientation relative to the earth: at the ends of the arcs, it was standing on its side, while in the middle, if was flat. So at the ends, the y-sensor would have measured gravity, while in the middle, it was the z-sensor; and in between, both of them at varying degrees. In theory, it would be possible to do a more accurate calculation by measuring the orientation at the points of zero speed, and calculating the intermediate positions; but that is rather complicated, and not required for this experiment.

Wednesday, November 7, 2018

Fun at the Slicks

More pictures, less words:
The forecast was 22 mph WSW, sunny, and warm. No surprise we got low 30s! We started sailing just before noon to catch the high tide at the Kennedy Slicks. GPS tracks:
Falcon 99, Loft RacingBlade 6.3, BP Weedspeed "38". Top speed (2 sec) 32.4 knots. My fastest 5x10 second average ever on a slalom board; I was faster only 3x on a 72 l speed board. Nina did freestyle, overpowered on 4.2. A bit too gusty there for freestyle, speed is more fun!

A video from one of the runs:

Sunday, November 4, 2018

Racing Lessons

One of the great things about racing is that it shows us where we need to improve. Sometimes, these are things that are not obvious during the typical back-and-forth sailing, but the prospect of more races in the future can motivate us to improve. In races that are mostly beam reach or slightly downwind, like the recent ECWF Hatteras races, jibes are very important. Here's a list of what to learn:
  1. Jibe dry on any equipment you may use in racing.
  2. Jibe dry in chop, with distractions, and at any spot - not just in nice flat water where nobody is near.
  3. Learn to adjust the radius in the middle of the jibe to avoid obstacles.
  4. Get back to full speed quickly after a jibe.
  5. Plane through jibes.
  6. Pick your jibe path so your competitors end up behind you.
Most of these points seem quite self-explanatory, perhaps even obvious. If you fall in a jibe, you'll loose a lot of ground. If you usually jibe dry, but never jibe around people or jibe marks, the distractions and extra chop may make you fall. If you're in the middle of the pack, you often have to adjust your jibe radius because a sailor in front of you crashes or comes to a dead stop. 

However, I had never realized the importance of #4 - getting back to full speed quickly after a jibe. I had often worked on #5, planing through a jibe. But whenever I come off the plane in a jibe, I'd usually take my time and wait for the next gust or swell to push me back up on a plane. On the second day of the ECWF races, when we had planing conditions for four races, I learned the error of my lazy ways ... 12 times in a row (in 4 races with 3 jibe marks). On the straights, I had at least similar, and often better, speed than the two guys (Andy and Keith) who finished ahead of me in most races. In the jibes, I came off the plane most of the time, but so did Keith. But it took me about 25 seconds to get back up to full speed, much longer than Keith, so he usually gained at least 100 meters at every jibe mark. 

I'm pretty sure Keith does not train much for races, so why did he get going so much faster? Perhaps the reason is that he usually sails in waves, which I (almost) never do. Wave sailing at Hatteras often includes a lot of slogging and pumping practice - be it to catch a wave, or to get enough speed to make it over the shore break. Lazy sailors get pummeled and don't catch waves! Nor do they get to beat wave sailors in races :-(.

Point #5, planing through jibes, is really just a logical consequence of #4. However, chances that you'll plane through a jibe in racing are always lower than in free sailing, since the jibe mark dictates where you jibe; other sailors create chop and may disturb the wind; and the jibe radius is often chosen to keep others at bay, or to sneak around them, which can make it hard to plane through the jibe. Even PWA slalom pros often don't plane through jibes! But you can always see them pump like crazy to get back up to speed.

The last point about picking your path is how Andy managed to win 2 of the 4 races, despite being on slower gear. Andy was usually third at the first jibe mark, but always had the highest approach, which allowed him to see where both Keith and I were jibing. He could then come in between and end up before us. At that point, it did not matter much if he planed through the jibe or not, since he blocking us. This approach requires quite a bit of experience, confidence, and skills - perhaps more experience than can be gained by attending one or two race events per year. Some of the top level slalom sailors now train slalom on Tenerife, with up to 20 races per day, often for several weeks in a row - that can amount to hundreds of training races! So I'll put this one on the back burner for now, and concentrate on regaining speed after a jibe. 


Saturday, November 3, 2018

Too Much

The forecast called for wind in the 30s (mph, that is). That's what we had when I started rigging - a 4.7, since the wind cannot be trusted. The 4.7 never got wet. Neither did the 4.0 that I rigged afterwards - I switched to the 3.4 Nina had rigged, since the wind had picked up:
I got onto the water when the wind averages where in the mid-40s, gusting into the mid-50s. I took advantage of this rare opportunity to sail in a lot of wind. A lot. Enough for the Red Bull Storm Chase. More than I had ever sailed in before. At one point, the averages where 49 mph, gusting to 59 mph. For those used to other units: 59 mph is 95 km/h, or 10 Beaufort - Windstärke 10, "Schwerer Sturm".
That was a bit too much for me, even on the 3.4. I pretty much had to waterstart in both straps; sailed out of the harness half of the time; had the sail barely sheeted in, and was nevertheless fully planing on my small FSW board. The wind was onshore, the tide was low, and I was wearing a helmet, so there never was any real danger. But the fun-factor was somewhat limited, and when gusts hit, I had a really hard time to keep the board on the water. Back on shore, it was not just blowing sand - it was blowing shells! Even getting the gear back to the parking lot safely was a 2-person job.

Usually, low tide and SW wind at Kalmus is flat and smooth, but not today. Eddie caught Nina trying a Shove It (when the wind was "only" around 25-40 mph):
A few minutes later, it looked a bit windier:
It still does not look that dramatic on the picture, but she came in a few minutes later, too overpowered on the 3.4. When the wind picked up a bit more in the next half hour, we had smoke on the water. At one point, I thought it was getting flatter again, because the wind was flattening out the little waves.

Well, finally getting a session on a 3.4 was all nice and good, but can we now please go back to being comfortably powered on 4.0 or larger?

Thursday, October 25, 2018

ECWF Hatteras Day 2

Yesterday saw the second day of the ECWF Hatteras, with freestyle before noon and racing in the early afternoon. Results will be announced tonight at a party at the Mad Crabber in Avon, but it seems quite certain that Andy Brandt and Nina won the freestyle competition.

We had about 18-20 knots for the racing. Here's the course from my GPS tracks:
Total course length was 3 km (just shy of 2 miles). My top speed was around 29 mph. I was behind Keith and Andy in three of the four races; in one race, I managed to come in second after Keith. Keith had the best starts and was first at the first jibe mark in at least three of the races; Andy had the better jibes and won two races. My jibes were dry, but mostly quite poor, and my re-acceleration after the jibes was much slower than Keith's. I shortened the distance between us on most legs thanks to higher top speed, but could never get ahead of him. The speed tracks above show that it took me almost 30 seconds to get back to speed after most jibes - way to slow. Now I know what I have to work on for next year!

In the first race, I started with a beach start right at the pin end, but I forgot to properly orient the board in time. When I straightened it out during the last seconds before the start, I ended up over the start line.  Unfortunately, I could not see the lower mark because of several sailors in between, and neither could I hear the announcements from the boat, so it was not until I crossed the finish line before I heard that I was over early.  I was not worried too much about it because I assumed that we'd have at least one discard with 8 races. That later turned out to perhaps be overly optimistic .. which would have meant that Nina (or perhaps somebody else) would have pushed me off the third place, even though I finished second or third in the other seven races. Now I'll have to wait until tomorrow evening before the final results are announced...

Wednesday, October 24, 2018

ECWF Hatteras Day 1

Race start at ECWF Hatteras. Picture by Outer Banks Kiting

Yesterday was the first day of the East Coast Windsurfing Festival Hatteras, organized by Mike Burns. After a skippers meeting in the morning, we started with light wind freestyle. Seven guys and three women competed in two sets of heats. They put on a great show that included just about any light wind trick you'll find in the Tricktionary, including Jaw Breakers, Ankle Biters, head dips, splits, back-to-back, rail rides, and all variations of turns and 360s. Things got "heated" for a minute when Keith pulled my clew on a close encounter and made me fall off - but fortunately, I was carrying a few balls for juggling, and threw one of them at him that scored a lucky hit. Swift punishment!

The afternoon saw 4 races in 10-12 mph. The course was mostly reaching or slight downwind, with an upwind leg at the start to spread out the crowd. Nina killed it on her Ultra Cat with her "new" (15 year old!) 7.5 m AeroLite race sail from Gonzalo, coming in first in three of the 4 races and second in one race. Andy raced a Flyer 280 foil board with a foil on an 18 in mast with a 7.8 Loft Switchblade. Despite not enough wind and too much see grass to get up on the foil, he was unreachable for anyone except Nina, and scored second places in three races. Since I was on my "new" Equipe 2 XR and (almost) nobody else had race boards, I came in third in most races.

I had been a bit upset the day before when I discovered that my 2-year old carbon boom for the 8.5 m sail I wanted to use was broken, without any crashes that could have caused this (at least not any I remembered). Fortunately, it had not broken completely while I was a mile away on the water, and Ocean Air had a replacement. But all that was forgotten the next day once the competition started. Seeing Nina kill it in both freestyle and racing was fantastic. Coming out ahead of Andy Brandt in freestyle was a very unexpected treat, for which I probably have to thank the very slick rails on the Windsurfer LT that Andy was using.

Here are the prelininary results after day 1:

Open Racing:

  1. Nina
  2. Andy
  3. Peter
  4. Keith
  5. Jason and David (tandem)
  6. Brian
  7. Ned
  8. Ray
Limited Racing:
  1. Tom
  2. Gaetan
  3. Simon
  4. Phil
  5. Randy
  6. LarrySergey
  7. Alan
Women's Racing:
  1. Pam
  2. Lisa
  3. Paula
  4. Mary
  5. Carole
Women's Freestyle:
  1. Nina
  2. Pam
  3. Lisa
Men's Freestyle:
  1. Peter
  2. Andy
  3. Ned
  4. Simon
  5. Jason & Keith (tied)
  6. David
Things will get mixed up today since we'll have freestyle and racing in 20-30 mph wind!

Monday, October 22, 2018

Everything Breaks

Everything breaks. Two boards (beyond repair). A few sails - one of them with 5 ripped panels. RIP. The whirlpool. The washing machine. The side door of the van. A weird fuel thingy in the van. Something else that gives the same error code (but at least we can still put gas in now). The mast foot on the Mega Cat (at least this one was an easy and cheap repair!). Today: the two year old carbon boom. At least it had the decency to bring me back to shore. I did not even realize that it was broken until I rearranged stuff in the van.

All that was annoying. More bothersome was when Nina was not able to windsurf for three weeks because of neck problems. Fortunately, they were just some muscles acting up, and things eventually got back to normal. Except that she then picked up something that looked like food poisoning. Twice in three or four days. But things seem to be back to normal again - well, mostly. She rocked at a light wind training session for the ECWF Hatteras today, even landing a Matrix and a Clew-pulling Anklebiter for the first time. The light wind freestyle competition tomorrow should be fun! Although a part of me expects something new to break...

Saturday, October 20, 2018

Hatteras Videos

As usual, we had a blast at the ABK camp in Hatteras the last 5 days. We had a nice mix of light, medium, and strong wind - here are a few videos, starting with a planing upwind 360:

A bit of light wind freestyle:


On the medium wind days, we got to try the foil demo gear from the ABK van. Fortunately, they had shorter masts that worked well with the water depth at the camp location in Waves. Here's a video where I prove that I can spin out a foil, too:


Nina, of course, did a bit better on the foil:


Plenty of wind in the forecast for tomorrow - mid-30s in the morning, dropping into the 20s after noon. We'll have a skippers meeting at Ocean Air in Avon for the ECWF Hatteras at 10 am - hope to see you there!

Saturday, October 6, 2018

Is 5 Hz enough?

This is a geeky post about GPS speedsurfing. You've been warned.

I am currently trying to get a couple of GPS devices that I have developed approved for the GPS Team Challenge. The units use u-blox 8 GPS chips, which are very accurate and provide speed accuracy estimates that can be used to automatically identify "bad" sections, for example artificially high speeds related to crashes.

One of the issues that came up is: at what rate should the data be recorded? Some popular GPS watches record only every few seconds, which is good enough for some uses, but not for speedsurfing. The venerable Locosys GT-31 recorded once per second; current Locosys units record at 5 Hz, every 200 milliseconds. The u-blox chips can record up to 18 Hz, although that limits the chips to using only two global satellite systems; for the highest accuracy, tracking satellites from 3 systems is desirable, which limits recording speed to 10 Hz.

There are some theoretical arguments that higher rates are better, because they give more accurate data. One big part of that is that random measurement errors tend to cancel each other out, and the more data points you have, the lower the remaining error gets.

But there are also some practical issues with higher data rates. The resulting larger files are usually not much of an issue, unless you're traveling to a spot that has a slow internet connection, and want to upload data for analysis to web sites like ka72.com.

Slow analysis and drawing speeds can be more of a pain. Most of the currently developed analysis software was developed for 1 Hz data, and can get quite slow with large 5 Hz files. Some steps appear to be coded inefficiently, showing N-squared time complexity - they take about 25 times longer for 5 Herz data. With 10 Hz data, add another factor of 4, and now we're talking about 100-fold slower.

A bigger issue is that higher data rates can lead to "dropped" points when the logging hardware can't keep up with the amount of data. I recently ran into this issue with my prototypes, and have seen indications of the same problem in data files from a GPS specifically developed for speedsurfing that's currently coming onto the market. But fortunately, the frequency of dropped points in my prototypes is low enough (roughly one point per hour) that the data can still be useful.

To see how much we actually can gain from increasing data acquisition rates to 10 Hz, I did a little experiment. It started with a windsurfing session were I used two prototypes at 10 Hz (for control, I also used 2 or 3 "approved" GPS units). Comparing the data on these units for the fastest ten 2-second and 10-second runs gives a good idea about the actual accuracy of the devices; the data from the other GPS units I used help to confirm that.

Next, I took one of the 10-Hz data files and split it into two 5 Hz files by simply writing one record to one file, the next one to a second file, the third one to the first file again, and so on. This simulates measuring at 5 Hz, but I get two 5-Hz files from the same device.
In the same way, I created a couple of 1-Hz files from the original file, this time selecting every 10th record for the first file, and every 10th record but starting one record later for the second file.

I analyzed the speeds for all these files in GPSResults, put them in a spreadsheet, and calculated the differences. Here are the results:
Looking at the "Average" lines, the observed differences increased from 0.041 knots to 0.074 knots for 2 second runs, and from 0.027 knots to 0.036 knots for 10 second runs. Going down to just one sample per second increased the observed differences more than 2-fold for both 2 and 10 seconds.

The observed differences are close to what would be expected by sampling theory, which predicts that the error is proportional to the square root of the number of samples taken. The expected numbers are shown in the "Theoretical error" line above.

But what error is "good enough"? Let's look at the top 10 teams in monthly ranking for the GPS Team Challenge for September to get an idea:
In the 2-second rankings, teams #7 and 8 are just 0.06 knots apart; in the 5x10 second average, the difference is 0.07 knots. The smallest difference in the 5x10 second category is 0.6 knots between teams ranking 8th and 9th.

Looking back at the observed differences at 5 Hz, we see that the average was just 0.036 knots (note that this is actually the average of the absolute differences).  For a 5x10 ranking, the expected error would be roughly two-fold smaller, or less than 0.02 knots. This seems quite adequate, it would have given the correct ranking in the 5 x 10 second category. Note that errors go down even more for the "longer" categories like nautical mile, 1 hour, and distance. Only in the 2-second category were two teams so close together that the observed average error is similar to the difference in posted speeds. Note, however, that many speedsurfers still use GT-31 devices that record at 1 Hz, and that even the 5-Hz Locosys units tend to have 2- to 3-fold higher errors than the u-blox prototypes I used in this test. It is quite well known that the 2-second category is the most likely to be subject to errors; however, it is still a lot better than the "maximum speed" category that is used in some other GPS competitions. For 5 Hz data, the expected error for single point "maxima" is about 3-fold higher than for 2 seconds!

So, to answer the question in the title: yes, it is!

Tuesday, September 25, 2018

ECWF Cape Cod: GPS Racing

It's been a couple of days since we completed the sixth annual East Coast Windsurfing Festival Cape Cod, and it's just beginning to appear possible that we might have it again next year. A longer report of the event will follow, but for now, let me talk about the GPS Racing.

The best wind of the weekend was last Friday, so I decided to hand out GPS units to anyone who was registered for the event and would take one. That included several Kalmus regulars (mostly non-speedsurfers), as well as PWA slalom pro Marco Lang. Since we all wanted to go to the event party at Inland Sea in the evening, we all had to stop early, just before the wind picked up, so most of the results were from 19 mph or lower wind averages. Here are the results:
Speeds are in miles per hour.  Everyone went faster than the average wind speed of 19 mph. Marco beat everyone by at least 4.5 mph (4 knots). Check out this picture of Marco flying on the fin:

The next group of three (PR, AR, and CE) all reached about 31.5 mph. Two of them (PR and CE) sailed exactly the same equipment as Marco; one (AR) was on slalom gear with a larger sail. Weight also plays a role in speed, but two of the three weighed in roughly the same as Marco - so the 4 knot speed difference is entirely due to skill.

The next sailor, NS in 5th place, stands our in a group of her own with 28.4 mph. She was also on full slalom gear, sailing happily along with Marco:
The last group of three sailors with speeds around 24-25 mph was on freeride or freestyle gear. Going just a bit of the wind is usually faster, as JSh's speed shows. All of them looked quite fast, and were going about 5 mph faster than the average wind speed.

All the speeds were from the Friday before the event. Since we never got enough wind during the event to run a GPS race, we used to top speeds from Friday for the GPS ranking at the event. Congrats to the winners, and many thanks to all who competed - and to Marco for showing what real speed looks like!

ECWF Cape Cod 2018

We had the 6th East Coast Windsurfing Festival Cape Cod last weekend. 21 windsurfers competed over the course of 2 days in racing, freestyle, SUP racing, and SUP relays. A big "thank you" to all that helped make this event a success, especially:
  • Marco Lang for traveling from Austria to participate at the event, answer many questions at the event party and on the beach, explaining the gear, and many helpful tips
  • Phil Mann from InlandSea for hosting a great party on Friday evening, organizing demo foils from Naish, and being at the beach both days to set up the demo gear and help anyone wanting to try it
  • Jason Meunier from VoilOka for driving the huge trailer with demo gear down from Canada, and setting up the demo gear
  • Bruno Robida from 2 Rad Windsurfing for financial support and raffle items
  • Vincent Lindauer for his efforts to get demo gear to the event, and for asking Marco to come to the event
  • Chris Eldridge, a local windsurfer and Fanatic/Duotone team rider, for help with the demo gear 
  • Peter Kimball from AP Kimball Construction for financial support and setting up a canopy for the event 
  • Jerry Evans from Chatham Wind and Time for making the trophies and financial support
  • Tom Ben-Eliyahu for help with the demo gear and driving the boat during the tow-in foiling
  • Barbara Baldwin for helping with registration and running the event
  • Joanie Scudder for arranging the sponsorship from Hy-Line cruises
  • Everyone who contributed to the Gofundme campaign to pay for Marco's travel expenses

Many of the people listed above had helped similarly in the past, and participated in the races during the event.

It was great to have demo gear from Fanatic, Duotone, and Naish at the event. Many of the competitors and a number of non-competitors took advantage of the opportunity to test new windsurfing and foil gear.

Next, a brief day-by-day description of the event.

Friday:
Phil Mann and Naish hosted a party at Inland Sea in West Dennis in the evening, with a Q&A session with PWA pro Marco Lang. It was well attended and fun, although most windsurfers arrived a bit later since we had a nice southerly breeze at Kalmus. The Fanatic and Duotone gear was already available at the beach, so many windsurfers tried new boards, sails, and foils.
To make sure that we would have a ranking in the GPS Racing category, I handed out GPS loaners to everyone I saw who was registered for the event, and had expressed interest in GPS racing. We had about 8 competitors in total. Marco Lang beat everyone else by about 4 knots, reaching a 2-second speed of 31.55 knots (2 second average) on a Duotone Warp 7.7 and a Fanatic Jag 108.

Saturday:
Side-off northwest wind from 10 to 30 mph created interesting conditions for racing, and challenging conditions for the freestyle competition. With a first race start shortly before 11 am, we managed to do five races and a couple of freestyle heats. Many windsurfers again took the opportunity to test race gear.

Sunday:
The wind forecast for the day was extremely light, and unfortunately came true. In the morning, Marco gave a very nice description of the Duotone sail range, followed by a description of the Fanatic boards by Jonathan when he eventually joined us.

After lunch, we ran SUP races and a SUP team relay, which again was tons of fun. We also used out little inflatable for "tow foiling", which created both astonishing rides and spectacular crashes.

Despite the very light wind, we managed to get one freestyle heat and the freestyle final in, where Mike and Henrikas displayed a variety of 360s, Ankle Biters, and more. When Henrikas failed to get his trade-mark Back-to-back in the very light wind, but Mike landed a clean Matrix, the decision when to Mike. Since Henrikas had won the SUP/shortboard class in racing, this set up a tie for the "King of the Cape" title. We had to dig deep into the tie breaker rules to find out who would be the King of the Cape 2018: Henrikas! Congrats to the new King and Jeanne, who is the 2018 Queen of the Cape.  I plan to post the full results of all disciplines in a separate post - for now, a few pictures:
Nina and Marco speeding on Friday
Racing action

Henrikas, King of the Cape 2018

Chris and Marco on the inflatable Fanatic tandem
Towing Tom
"Best Stoke" winner Spencer
Mike mid-Matrix
Freestyle can be exhausting!
Happy winners Ansel and Martin

Overall, it was again a fun event. Many competitors and demo gear users came to us after the event to thank us (which is definitely appreciated!). The stoke was high even on Sunday, when the wind was very light - we know how to have fun even without wind!

You may want to stop reading here.
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Unfortunately, the light wind also seemed to keep some windsurfers away. The low attendance, despite moving the event by a week to get better wind, and despite demo gear and a PWA pro as the "guest star", makes it questionable whether there will be another ECWF Cape Cod in the future. Organizing the event is quite a bit of work in addition to the event days - just getting the signatures from all necessary town officials can take a day, and that's one of the easier parts. The organization we formed specifically to host events like this, the ECWA, ended up loosing money on this event; unless the ECWF Hatteras in October is a big success, we would need to cut expenses at future events.

Every event will have some unexpected things happen that cause stress for the organizers. Some of these can't be helped, like crashing scoring programs or some random idiot driving over the ladder we use to put longboards on top of our van. But other thing are very demotivating. As most of you know, the event was run by a German couple. Germans expect that if you give a word, you stick to it (well, at least Nina and I do!). If a local shop or the representative of a big windsurfing company says he'd bring or send items for the event raffle, and then does not, that's a big disappointment. For the local shop, we are fortunate enough to have another local shop that has always supported the ECWF (Inland Sea Windsurfing). For the large company, we will try hard to separate the person who apparently forgot his promises from the company (which we love), but it's not easy. And just for future reference: no, it it not ok to come to an event, to not register, to not sign the liability waiver, but to insist on racing on equipment that the event organizers and race director have specifically excluded from the races. You are free to disagree, of course, but just joining a race on equipment that was deemed too dangerous for this event is extremely inconsiderate and arrogant. Stating that you would "stay away from everyone", and then later posting picture where you are right next to several others in the middle of the race? Priceless. (Other words come to mind, but shall remain unwritten)

I run a small company. We have often presented our products at meetings where we had access to a number of potential customers. Every single time, we had to pay for this opportunity - often thousands of dollars. For the ECWF, we did not ask for money, since giving the local windsurfers the opportunity to test gear was more important for us. We did, however, ask for at least a small contribution to the raffle, which gives windsurfers an extra reason to join the event. Despite promises, we did not get anything. We thought that a company might at least contribute to the cost of getting one of their team riders to the event, especially in a year where they have a significantly increased marketing budget since they changed their name. Again, nothing. Well, "Denken ist Glückssache".

I am trying hard to focus on the great people I got to know at the event, or who I have known and who have participated and/or helped again, rather than on the few negative experiences, but it's a bit of a struggle right now. So unlike last year, where we started getting the permit for the next event soon after the event, we won't plan next year's ECWF Cape Cod before our trip to Australia. There, we'll attend a few events and races, and speedsurfing on some of the top spots in the world, and wave sailing in some of the best waves in the world, will hopefully put things into perspective.

Wednesday, September 12, 2018

Marco Lang at the ECWF Cape Cod!

It was a bit of a bummer that we had to move the ECWF Cape Cod back one week because of very light winds, but it had one great side effect: we will have a "special guest" again! This time, it's Marco Lang, a top-level PWA slalom sailor from Austria.

Marco finished 7th overall on the PWA slalom last year, and won the PWA slalom in Sylt. He is sponsored by Fanatic and Duotone, which also sponsor the ECWF.

To pay for Marco's flight to the US, we started a fundraiser on Gofundme - please feel free to help with a donation! Five local windsurfers have donated $420 in the first couple of hours of the campaign, but we still need more contributions to reach the goal of $1100. What would you give to be able to get tips from one of the best windsurfers in the world, and to ask him questions about speed, racing, or freestyle?

Here are a couple of more pictures from the Fanatic Team website:


For more pictures and videos, check Marco's web site or his Facebook page!

Big thanks to all who have contributed to the fundraiser, and to Vincent Lindauer for inviting Marco! I hope to see you all in Kalmus on September 22nd and 23rd!

ECWF Cape Cod Now September 22-23!

In view of a forecast of very light winds for this weekend, we will use the "no wind" option and move the ECWF Cape Cod back one week, to September 22-23. Here's a graph that shows the wind forecast for Sunday noon:

Sunday forecast from Windy.com (European model)
The forecast from iWindsurf.com looks pretty similar:

Wind forecast from iWindsurf.com (US model, GFS)
Unfortunately, the European and US computer models agree, so it is very likely that there will be no wind on Sunday morning - not even enough for longboard racing! Both days, the wind will most likely to light for planing races or to test the demo gear that several sponsors will bring.

We do not yet have meaningful wind forecasts for the weekend of September 22-23, since wind forecasts are very unreliable for a week or more out. However, days with as little wind as shown in the forecasts above are quite rare on Cape Cod, so it will probably be windier.

To see what the event participants thought about moving the festival, we send out emails to everyone who had already registered, and posted a poll on Facebook. The response was an overwhelming vote for moving the ECWF a week later:
In the poll, 14 windsurfers said they would only come on the second weekend, while 3 windsurfers can come only on the original weekend. The (fewer) email responses showed a similar pattern.

Therefore, the East Coast Windsurfing Festival Cape Cod will take place on September 22-23.

Saturday, September 1, 2018

So Much Fun

"I don't know why this is so much fun!" That's what Nina said during and after a windsurf session a couple of days ago. For a bit of context, here's what the wind meter readings looked like:
We sailed from about 4 to 6 pm. The wind was about 10-15 mph, with lulls down to 6 and gusts to 18 mph. That's not wind where most "sane" windsurfers would even bother to go sailing, but Nina had a big, fat grin on here face the entire time.

The reason? She was on a 30+ year old "round bottom" longboard, the Magnum 390. She was fast the entire time, even in the lulls, with a 6.5 m sail. She also snapped the board around on a dime when it was time to turn, and I don't think she crashed at all. We started at Kalmus in offshore wind, and sailed across the shipping channel where the wind was a bit steadier. When I dragged my WindSUP across the sandbar to see if the water in the "baby bay" at Egg Island was flatter (it was not), Nina sailed around and met me a few minutes later.

Why was it so much fun? I can only guess. I think a big reason is the excellent glide of the Magnum, which either is a D2 board, or at least quite similar (the back end is a bit flatter, and the nose is not quite as pointy, as other D2 boards). The board reaches about 8 knots speed in maybe 5-6 knots of wind, which feels almost as fast as planing on a shortboard. Another part of the fun may have been that the board is not that easy to sail, so it may have required a bit of concentration .. can you say "zone"? I also had fun working a bit on my back-to-back in gusty conditions, but the girl sure had more fun.

Things evened out a bit the next day, where I had a fantastic session in 10-20 mph wind on my F2 Lightning in Barnstable Harbor, while Nina stayed home. It was a beautiful day, and planing near the dunes on the far side, with miles and miles of water just for me, was just about perfect. I did not even mind the little swim when the mast foot came loose and the board started to drift away. Perhaps my conversion to a standard single-bold mastfoot needs a bit of a refinement...


Sunday, August 26, 2018

ECWF Cape Cod and Hatteras


Ladies and gentlemen, get your race gear ready, and polish your freestyle tricks - two East Coast Windsurfing Festivals are coming up in September and October! Both will include racing, freestyle competition, demo gear, a raffle for participants, and lots of fun!

The first ECWF will take place in September at Kalmus Beach in Hyannis, Cape Cod. The planned date is September 15 and 16 (with a social event on Friday evening before the action), but if the wind forecast looks bad, we'll move the ECWF Cape Cod to September 22-23rd, so that the demo gear from Fanatic and Duotone can be tested in planing conditions. This will be the sixth year in a row for the ECWF Cape Cod, so register now and join the fun!

The second ECWF this year, the first annual ECWF Hatteras,  will be run by Mike Burns at Ocean Air in Avon, NC, in the week of October 20-27. We are very excited to have an ECWF-style event at one of the best windsurfing spots in the US! The huge amounts of fun we had at Mike's original ECWF events on Long Island were a major reason why Nina and I started the ECWF Cape Cod in 2013. Chances are good that we'll have one day of high-wind racing and a day of light-wind racing, plus a day of freestyle competition, in Hatteras, since competition will take place on the days with the best wind between Monday, 10/22, and Thursday, 10/25. You can register for the ECWF Hatteras at www.ecwindfest.org/register_hatteras.php. Hope to see you there, and at the ABK camps on Cape Cod and Hatteras a week before the events to learn new tricks!

Saturday, August 25, 2018

Punch the Giant's Nose

This post is not about boxing or football, sorry. It's about the loop. I like simple explanations, especially when thinking about a move that takes only a second. How many things can you think about in a second? For me, the answer is "one" - maybe two on a good day.

Some old loop instructions were simple: "Jump high and sheet in!". That actually did work for some people. But for many others, the advice resulted in "killer loop" attempts that broke gear and bones. You'll probably have a hard time finding a professional instructor who uses this advice. Broken gear and bodies are not good business.

I've been looking at loop videos a lot recently, and noticed a few things. Let's start with a picture:
This is from a Josep Pons video that I blogged about in the past. He is setting up for the loop. Note that his body is over the board, and both arms are bent, with the elbows at roughly a 90 degree angle.

Now check the next picture:
Josep is starting to take off, but the board has not yet left the water completely. The mast has moved towards the windward-forward side, and his front arm is fully extended. The back arm is still bent, but the hand is over his head.

Mr. Pons has some of the most beautiful loops in windsurfing. Lots of PWA pros line up to get lessons from him, often to work on double loops. Imitating him seems like a good idea!

The movement of the front arm is punch-like. Just imagine a giant standing on the front-right side, and Josep trying to punch his nose! The back hand also goes up; with the giant there, I guess he's protecting his head from counter punches.

The bent front arm in the first picture means that the sail is partially de-powered: bending the front arm sheets out, the same way as extending the back arm would. In the loop, the sail must be partly sheeted out at the beginning, so that the mast can be moved to forward-windward (where it is in the second picture).

Punching up helps to lift the nose of the board for lift-off. Interestingly, extending the front arm to punch the giant's nose also exposes more of the sail to the wind - it effectively sheets in. That starts to turn the nose of the board downwind, which in turn exposes even more of the sail to the wind - I call this "automatic sheet in".  This can be clearly seen if you compare picture 2 to the next picture, where the board has just left the water:
We've just punched a giant in the nose. That made the giant angry! I think it's a really good idea to make ourselves really small now, so the giant has a smaller target:
By curling up into a ball, we can rotate faster. If you've ever tried a somersault, you know that! In the process, we also pull up with the back foot, which keeps the tail of the board from going back down into the water prematurely.

If you're learning the loop and managed to first punch the giant's nose like Josep, and then curl up into a ball, you're well on the way to at least landing on your back, hopefully in a position to water start, so I won't go into what comes next - I think that's comparatively easy, if you managed to get into the position shown in the last picture above.

So, here's the really simple loop instruction:

  1. Before takeoff, get your body over the board. Sheet out by bending your front arm.
  2. As you go up the wave, punch the giant's nose. Just remember that the giant is standing on the windward-forward side of your board, and not on the nose of your board!
  3. Once in the air, pull up with the back leg and make yourself small. Enjoy the ride!
As I am writing this, I can't help but think back at the one time I actually fought a giant. Maybe "fought" is an overstatement - it was just point sparring at a Kempo Karate tournament. Maybe he was not really a giant, but he was at least a head taller than I was. The fight was over quickly. No, I did not manage to punch his nose - I had never before sparred with anyone who was a lot taller than I am, so I really had no clue. But the giant in the loop is imaginary, so he should be easier to hit, right? I won't say he does not hit back, though - I have had a few hard backslaps in earlier loop tries. Maybe it helps if I hit harder :-).

Wednesday, August 15, 2018

ABK Camp Hyannis Questions

The ABK windsurf camp in Hyannis is coming up less than 4 weeks (Friday 9/7- Sunday 9/9/2018). This post contains some of the questions we are often asked about it, and (more importantly) the answers.
  • Is an ABK camp right for me?
If you are a windsurfer who wants to get better or learn new things, or if you want to learn windsurfing, the answer is "Yes!".
  • Will it be over my level?
No! ABK camps are for windsurfers at all skill levels, from "never before" beginners to experts working on freestyle moves and loops. There are typically 5-6 groups of different skill levels, and you'll be in a group with windsurfers of similar skills. There is usually  at least one group that works on jibes and tacks - be it to learn how to jibe without falling, or to tack a smaller board, or to plane through jibes.
  • What are the temperatures like? 
Typically, air temperatures are in the 60s early in the morning, and in the 70s during the day. It may get a few degrees colder if we have northerly winds, or on occasion reach the low 80s. Water temperatures are usually in the low 70s or high 60s (currently 75-80ºF).
  • Do I need a full wetsuit?
You may not absolutely need one, but it's probably a good idea to bring one, especially if the weather is on the colder side of the range. It may be warm enough for board shorts and lycras, but keep in mind that students typically spend time in the water in the morning and in the afternoon. Also, you may fall more often than usually since you'll be working on new things!
  • Will it be windy?
September is usually a pretty windy month on Cape Cod, so chances are high that you'll get at least one day with enough wind to plane during the three-day camp. In 2017, we had 2 windy days (5 m sail for lighter sailors, 6 m for guys like me). In 2016, we also had planing conditions on two days; in 2015, one day; in 2014, two days.
Note that there's tons of stuff to learn even in light wind that will help your high-wind sailing. For example, my lovely wife learned how to get into the back foot strap on a light wind day.
  • How big are the waves?
Kalmus has a reputation for being choppy, especially on very windy west-southwest days around high tide. However, the ABK camps usually use several options to allow campers to learn in less challenging conditions. Depending on wind direction and skill levels, some or all groups will often sail on the Lewis Bay side (which is not available for windsurfing in the summer, but becomes available after Labor Day). More advanced groups sometimes sail across the channel to Egg Island, where the water can be perfectly flat even in very strong wind - perfect for working on jibes, 360s, Vulcans, and more.
  • What can I possibly learn in 3 days?
That will depend a bit on you. Typically, windsurfers with less experience or those working on brand-new skills can progress more quickly than windsurfers who have sailed for many years without instruction, and then have to unlearn bad habits. I am a slow learner who falls into the second category, but nevertheless, I learned to plane through my jibes within a couple of days during my first ABK camp. My lovely wife, who learns faster and had fewer bad habits to unlearn, learned these things in her first ABK camp in Hyannis:
  1. The light-wind helicopter tack.
  2. Consistent water starts. She had done a few before, but usually would be totally exhausted when she got up. The ABK camp fixed this for good.
  3. Planing in both foot straps (she had learned how to get into the front strap at a previous ABK camp in Bonaire).
These skills were pretty solid - she had no problems sailing in 30+ mph wind on Maui and in the Gorge a few months later. As I said, she is a fast learner, and other campers may learn less, but usually, everyone goes home happy with new or improved skills at the end of a camp.
  • How many windsurfers and teachers will be there?
Typically, there are about 20-25 students in the ABK camp Hyannis, and 4-6 teachers.
  • How about food at the camp?
The Kalmus snack bar is right at the camp site, and offers surprisingly good food at reasonable prices. Theoretically, you'd also have enough time to drive 5 minutes into town, but I don't recall ever seeing anyone doing that.
  • When should I register? 
Register now! The ABK camp Hyannis usually fills up. Since the student-to-teacher ratio is fixed to ensure high-quality learning and teaching, Andy often has to turn people away who try to register in the last days before camp or on-site. But if everyone registers early, it is often possible to get another ABK teacher to come and to add another group. So register now! See you at the camp!




Thursday, August 9, 2018

Bad Behavior

Let me start with a story. A bit more than a week ago, we were sailing in the late afternoon in a typical southwest wind at Kalmus. A beautiful, windy day. I'm standing in the water near shore, trying to get reoriented after a failed 360 or some such thing, when suddenly I hear a loud bang, a splash, and an "Oh no!".  One of the Kalmus regulars had been de-rigging in the water, as she often does. Another Kalmus regular had not seen her there, and jibed near shore. He just noticed her in the middle of the jibe, and his boom hit her board hard - hard enough to require a proper repair, ding stick would not have done.

The jiber was a guy who is (a) a pretty good windsurfer, (b) usually stays out of everyones way, and (c) is a nice guy. He's definitely not an aggressive windsurfer, and was very sorry about the accident. There may be a guy or two who sail Kalmus often where you might expect such a thing to happen, but definitely not with him.

Why did it happen? Quite simple: he was coming in against the setting sun, which severely limits visibility. He simply did not see that there was someone standing in the water. Nor did he see the board in the water until it was too late.

Why am I telling this story? Just to illustrate that accidents can happen, even with competent and careful windsurfers. Poor visibility against the late afternoon can be a big contributing factor. Note that in this instance, the person was standing in the water, and a board and sail were next to her. She was definitely a lot easier to see than the head of a swimmer in choppy water.

This (finally!) brings me to the real topic of this post: do not windsurf (or kite) through the swim area at Kalmus! This rule applies even when there are no life guard on duty. Looking at the accident I described above, it is actually more important in the late afternoon after the life guards leave, since the visibility is worse than during the day. If there is anybody in or near the water in the swim area, or even a chance that someone may want to swim, the entire swim area is a definitive no-go zone.

Most windsurfers who sail at Kalmus on a regular basis know this rule, and act accordingly. When the wind is straight onshore, it can be a bit hard to clear the buoys that mark the swim area, but almost everyone understands that safety is more important than avoiding a tack. Every now and then, someone who has not sailed at Kalmus does not know about the rule, but they are usually quickly informed about it by the regulars, and then stay out of it.

Of course, there are exceptions. Some thing has encourage some people to behave badly and aggressively in the past year or two, and there have been several instances where the person asked to not go through the swim area started arguing, and simple refused to listen, regarding his own convenience higher than the safety of others.

The first instance happened a few days ago. In this case, it was a kiter who routinely went through the swim area, and in at least one instance also kited very close to a beginner windsurfer (less than 2 feet away). This was quite threatening to the windsurfer, and definitely not safe. When her husband later ask him to keep a safe distance, the kiter denied sailing close to the windsurfer (despite this being witnessed by at least 2 people). When asked not to kite through the swim area, he insisted of having a right to do so. When other windsurfers in the neighborhood confirmed that he should not kite through the swim area, he started complaining about "harassment", and "threatened" to call the police. The windsurfers encouraged him to do so, since the outcome was predictable: the police came when he called them, and informed him that he is not allowed to sail through the swim area. They also mentioned that he would be banned from the beach if he continued to do so.

Just a couple of days later, a similar thing happened, this time with a windsurfer. It was a windy SW day, and about 30 windsurfers were on the water during the day. All of them avoided the swim area the entire day, except for one guy who showed up shortly after the life guards had left, and promptly proceeded to sail through the swim area. Several of the locals asked him to stop doing that; one of them was my lovely wife. When I jibed close by, I heard him yelling at her, so I walked over, and also asked him not to sail through the swim area. We tried to explain to him that endangering swimmers could get the only windsurfing beach in Kalmus closed for windsurfing, but he insisted that he had been sailing at Kalmus for 30 years, and had the right to go through the swim area. He also complained about having had a bad day at work, as if that gave him special rights. Eventually, he stated that he'd sail through the swim area even more now because of the "nagging" - which he then did, for several hours. During that time, he proved that he definitely was a good enough windsurfer to go upwind to avoid the swim area - he nailed fast tacks on a board that barely had enough volume to keep him above the water. He also proved that he was quite willing to aggressively defend his "right" to go through the swim area, at one point choosing to hit me with his boom rather than changing his angle to the wind when we were on a collision course at low speed. I was the downwind sailor and verbally asserted my right of way, but I think it is safe to assume he does not know or care for right of way rules (another Kalmus regular, Don, had an almost-collision when the guy refused to change his course, coming out of the swim area on port, while Don was pinching upwind on starboard to avoid the buoy).

There were several of our windsurfing friends on the beach who witnessed his behavior, and got rather upset about it. Someone had a camera, so pictures were taken of him sailing through the swim area on almost every run, and of the license plate on his car.

After two such incidences in about as many days, I must admit that I was starting to be confused: did the water really convert to a "no rules" area as soon as life guards went off duty? That did not make sense; was not what the police had actually said; and was not what almost everyone I talked to on the beach thought, but it deserved a check. So I place a call to the Director of the Barnstable Recreation Department, whom we know from organizing the East Coast Windsurfing Festival, to double-check, and perhaps ask for advice how to handle such situations.

But before I received a phone call back from the town, I had talked to this incident with another windsurfing friend who sails Kalmus about as often as I do, Joanie. She reported that she had a similar frustrating conversation a week earlier, where the guy also ignored the request not to sail through the swim area, and claimed to have sailed Kalmus for 30 years. Sounded like the same guy, and a quick email exchange of pictures confirmed it. So this was definitely not the first time the guy had been asked.

Funny thing is that Joanie has been friends with Patti Machado, the Director of the Barnstable Recreation Department for several decades, and that they ran into each other the next day by chance. They talked about the "Bad Behavior" incident. Patti, who bears responsibility for safety at Barnstable beaches, confirmed that sailing through the swim area when people are in the water is an absolute no-no. She suggested that we'd get the license plate numbers, and send them to her, so she could send a formal letter to the offender; repeat offenders would face a ban from all Barnstable beaches that would be enforced by the police and the Harbormaster. Since we already had the relevant pictures, I simple send them along by email, and a letter was sent the same day.

Hopefully, it will never be necessary to actually issue a beach ban, but it is nice to know that such selfish and potentially dangerous behavior will not be tolerated. Note that this is not about someone accidentally drifting into the swim area because they are beginners, or the wind suddenly dies, or some such thing - that can happen to anyone. It's quite obvious if someone is trying to stay out of the area, or if he just ignores rules because he regards them as inconvenient.

So, what should windsurfers do when they see someone sailing through the swim area? Simply inform them that the swim area is off limits for windsurfing, even if it is inconvenient, the life guards are off duty, or no swimmers are in the water at that moment. The vast majority of windsurfer will say "I did not know" and follow the rules. If someone is curious about the rule, go ahead and try to explain it. But don't get into an argument with someone who thinks the rule does not apply to him, or states you should not "nag" him or talk to him, or gets aggressive or loud. Perhaps point out that the town is perfectly willing to enforce the rule, all the way to a complete beach ban. If someone ignores the requests and repeatedly sails through the swim area, feel free to take pictures and send them to the Department of Recreation, so that they can help clarifying and resolving the situation.

Of course, there is also the issue of swimmers being outside of the swim area on windy days. When the life guards are on duty, they usually walk over and ask the swimmers to move to the swim area; but what if they are off duty? I suggest to politely inform the swimmers where the swim area is, and to suggest to them to move over there for their own safety. Of course, windsurfers have to avoid swimmers even outside the swim area, but on a windy day, it can be hard to impossible to see a head among the whitecaps, especially against the setting sun. It may be necessary to explain that windsurfers may be traveling at up to 30 miles per hour; may not see swimmers; cannot always stop suddenly; and may loose control of their gear. At times, I have turned over my board and pointed to the fin to explain that they probably would not want to be hit by such a thing, even accidentally; that worked quite well with large pointer fins.

Asking swimmers to move to the swim area really only works when windsurfers stay out of the swim area. Even a single windsurfer who goes through the swim area on a regular basis can make the request to move seem rather non-sensical - which is a good reason to stay out of the swim area even if there is nobody in the water at a given time. During a summer like this one, when the water is warm and the heat and humidity sometimes seems unbearable, it's just a question of time until someone wants to go for a swim.