A brief tow test today. We mounted a Hemisphere GPS compass on the stern pole in order to compare readings with the Airmar to aid in compass calibration. At the beginning of the test, we towed the boat in two circles at about 5 knots, then towed to Treasure Island to look for wind, where we towed the boat in two 23-knot circles. After finding no wind, we circumnavigated the island and towed in two more 5 knot circles on the way home. Jacques Vincent and Paul Larkin joined us on this test. We again used Paul’s headsets on K2 and the Protector, with mixed results.
Today we debuted both the telescoping launch mast and the line angle sensor. Martin Bretschneider joined us again, as did Paul Larkin. Before the kite test, we towed the boat in a large hexagon at about 5 knots. The purpose of this tow test was to record the boat moving in a straight line at six different headings, in another attempt to verify that the compass is working correctly. We are still not satisfied with our measurement of the true wind angle, as the numbers we’ve generated don’t match up with with geometry of the gps track. After the tow test, we put up the kite for some more downwind sailing practice. We were able to launch with the new mast […more]
Another successful low wind test today. We took the 50 sqm kite again, but this time we extended the lines from 60 m to 80 m to catch a bit more wind. Prior to launching the kite, we towed the boat in large slow circles again to calibrate the wind sensor compass, this time successfully. We then towed to Treasure Island and practiced down wind runs again, toward Berkeley. We dropped the kite in low wind near Emeryville and towed back to TI to launch again. When we re-inflated the kite, we ran out of compressed air, but still managed to launch and begin sailing with only 1 psi (instead of 4.5). By the time we ended the test 40 minutes […more]
Today we headed out to Treasure Island for a test. We initially had trouble launching the 50 sqm kite because the wind was so low, but then we hit 33 knots on our first run, in only about 12 knots of wind. As noted in previous posts, we are improving our measure of true wind angle in order to better understand how to maximize our speed downwind. For this test, we practiced sailing at (and measuring) different wind angles between TI and Berkeley Marina (see attached screenshot). Martin Bretschneider joined us again, and he took a turn at the kite helm.
Today I did some tests of the GoPro remotes.
Hooked up 7 GoPros (4 Hero2s with WiFi bacpacs, 3 Hero3s) to one remote. It was very difficult to synch more than that to one remote. I also hooked up a separate GoPro to the phone app. I placed them around the boat. Upon turning on the first remote, it bounced between 6 and 7 cameras ready. When it bounced back to 7, I started recording for all 7. Checked to see all were recording, hit stop and repeated this process three times standing on the tramps, the hull near the nose, and the hull near the rudder. Each time I also entirely powered them on and off via […more]
Today was a beautiful day to test our wind sensor, Paul Larkin’s headsets, and our new GoPro Hero3 cameras. We also performed a brief kite test using the new 18 sqm kite. Paul’s friend John Bond joined us on this test.
First, we compared our primary wind sensor, an ultrasonic model, to a standard cup-and-vane sensor. In the past, we have seen suspicious readings in true wind speed and direction that we attributed to compass miscalibration or poor alignment of the sensor with the boat. In the last test, however, we collected data that showed that any compass or alignment errors that exist are far smaller than the discrepancies that we have seen. This data indicates that the basic apparent […more]