Monday, November 21, 2011

Closer is faster

One of the great things about being part of a speedsurfing team is that you can examine the tracks of better team members afterwards and learn from them. The first time I went windsurfing with Dean, I learned that I needed to go a lot deeper downwind for top speed. Even now, a year later, I often discover that I did not go nearly as deep downwind as I thought when I look at my tracks in the evening.

Our great little speed session at Egg Island two days ago has provided some more material for learning to sail faster. Both Nina and I improved our previous top speeds by about 3 knots, but there is still a lot of room for further improvement. Here is a comparison of the GPS tracks from our fastest runs (my track has the blue label):
The biggest obvious difference is where we reached our top speed. My top speed was close to the sand bar, where the water was very flat; Nina's top speed was pretty far out in the bay, where the chop got sizable. The main reason why she stayed away from the sand bar was that she was afraid of hitting ground at shallow spots. I had walked the entire length of the sand bar at the start of the session, so I was comfortable getting closer to it, but I still stayed about 40 meters away from it. In most of my runs, I felt that the chop was limiting my speed - as soon as I approached top speed, the chop got so high that I throttled back to avoid crashes. I find it pretty amazing that Nina hit her top speed that far out. Yes, she was on a 49 cm narrow F2 Missile that handles the chop (even) better than my 58 cm wide Fanatic Hawk, but still. As for the top speed difference, keep in mind that Nina almost never goes for speed; that she weighs next-to-nothing, at least compared to me; and that she was using a 4.5 m wave sail instead of the cambered larger race and speed sails that Dean and I were using.

Now let's compare my runs with Dean's. Dean has been playing the speed surfing game a while longer, and he got a lot closer to the sand bar. Here is a comparison of my fastest run to his second-fastest run of the day:
He was about 1.6 mph faster than I was by staying closer to the sand bar. He reached his top speed right at the tip of the sand bar, where the water was flattest. He then kept close to his top speed for several hundred meters into the bay, which speaks for his skills and the chop-handling ability of his Tabou Manta board.

In my four fastest run, the top speeds were very close to each other (57.24 - 58.23 kmh). In contrast, Dean's fastest run was quite a bit faster (62.98 kmh) than his second-fastest run (60.64 kmh). Here is the comparison of our fastest tracks:
Dean was much closer to the sand bar for the entire run, and the smoother water enabled him to accelerate much faster and to reach a higher top speed. It is quite amazing what a difference 100 feet can make! It is quite unlikely that I would have beaten his speed even if I had sailed so close to shore, but I probably would have picked up another knot or two.

For Nina and myself, one goal for the day had been to practice the Slingshot. We definitely had this in mind while sailing, and played around with it somewhat. I don't think that I did one that was good, mostly because the chop on the approach to the sand bar made it seem advisable to start going a bit downwind earlier for more control. Looking at the tracks now, I think that might have been a mistake: holding a steeper angle longer to get closer to the sand bar before bearing off probably would have been faster. But I might need a few more days of practice before I approach a sand bar at 25 knots with the plan to Slingshot myself downwind just a few seconds before hitting it at full speed!
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One thing worth mentioning is that I was using the GPS Speed Talker application the entire time that day. It sure was nice to here it telling me 30, 31, 32 knots! The top speed on the Android phone was 0.5 knots higher than from the GT-31, but overall, I think it was pretty accurate, and definitely helpful.

I had planned to use Nina's bluetooth-enabled BGT-31 with the Speed Talker app, but when I tried to set this up, I discovered that updating the firmware on the BGT-31 apparently has removed all bluetooth options from the settings - the menu items are simply missing! I know that they were there initially, because I tried to hook the BGT-31 up to my Mac when we got it. I tried re-installing the older firmware version from the Locosys web site, which worked - but it did not restore the bluetooth menu items! So if you have a BGT-31, think twice before "updating" the firmware version!

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