Today we performed a second tow test of the new kitefoiler. Some minor repairs had been made since the last test, the sensors and foils were adjusted, and the tiller was strengthened. The boat now weighs in at 390 lbs, which is a larger increase than expected. It is possible that we under-measured the kitefoiler weight before the first test.
This time Don manned the helm. We were able to get the boat more stably onto its foils, especially after Dudu and Joe began to adjust the foil angles manually. We found that there was interference from the bottom of the cassette fairing. We will make a mod in the morning and be back out there tow testing first thing.
In this test we were able to collect a good clean dataset which indicates that the boat rises out of the water at 14-16 knots, requiring a pull of about 140 kgf to get it there. Once out of the water, the required force drops to about 50 kgf.
The graph of time vs. speed and towing force is a detail of two towing runs out of a total of 12. The speed vs. force plot shows the average load to achieve a given speed over all tests.
Time: 2:30pm – 4:30 pm
Location: Alameda to city
Boat: Kitefoiler + Protector
Crew On Boat: Don, Joe, Dudu
Shore Crew: Damon, Jamie, Richard, Betsy on Protector
Camera Count: 5 HD GoPros (portfoil, starboardfoil, tfoil, undertramp, peoplecam); 7D on Protector