Author: betsy

Kitefoiler mast test – March 11

3/11/11

Today we tested the new kite-launching mast on the Kitefoiler for the first time. The setup includes the K1 winch with custom platform, two carbon windsurfing masts with extensions, and an intricate system of pulleys.
Don, Joe, and Dudu successfully launched the kite three times, but had difficulty transitioning from launch controls to sailing controls. Overall, the test went well, as each successive launch improved upon the last. However, they attempted a fourth launch, but the kite lost air after hitting a sharp carbon piece on the bow.
Today was also the first test of some of the new modifications to the boat, including steel reinforcements on the rail moldings and bronze bushings and smaller wheels on the […more]

New Logger Thermal Test

3/2/11

Jamie put the logger components in a new box (orange, on top) that is even smaller than the old box (silver, on bottom). Right now he is running a program on the Android phone to record the temperature to make sure that the electronics will not overheat in their new closer quarters.

The graph shows the temperature recorded by a Nexus S phone, using software that we wrote to log its battery temperature. (The PC either has no non-CPU temperature sensors or they are not visible to the OS.) The phone battery temperature is typically a few degrees higher than the ambient temperature. While the temperature did not fully stabilize during the 2.5 hour test, it appeared to be leveling […more]

Kitefoiler Tow Test – Feb 10

2/10/11

We towed the Kitefoiler again today. We added a pulley system that allows us to adjust the J-foils from the steering position at the stern of the boat. These pulleys worked very well. The port foil was sticking and not moving correctly as it did yesterday, but due to the glassy bay conditions, this did not prove a problem for our very short test. Henry visited the shop today and rode on the boat with Don and Joe.

Three Kitefoiler tow points were tested, each with the powerboat pulling at at 45 to 60 degree angle. The graph shows the measured forces and speeds for each tow point. The 3rd point appears to have reduced the load over the 1st. […more]

Kitefoiler Kite Test – Feb 9

2/9/11

We took the Kitefoiler out today for a second test with a kite. We spent a bit of time hunting for wind, but found a reliable source east of Alcatraz and Angel Island. Dudu helped launch the kite, then left the Kitefoiler so Don and Joe could pick up speed. He later returned to the Kitefoiler to see if his extra weight would make it easier to steer at top speeds, which it did. We achieved the fastest speed yet for this boat, 27 knots. The kite bridle looked loose in one place, although it did not cause kite steering difficulties.

First Kitefoiler Kite Test – Feb 4

2/4/11

We performed the first Kitefoiler test with a kite today. Greg Ketterman, designer of the Trifoiler, joined us on the test. Prior to testing with the kite, we towed the boat to the city and back around Treasure Island to make sure that everything was working as expected. The foils were a little looser than we would have liked, but the wind picked up, so we tried the kite anyway. Despite the mediocre wind speed, the boat performed very well, foiling consistently with two crew members in the area between Angel Island and Chrissy Field. After returning to the shop, Joe disassembled the cassettes and found the problem with the foils–the stress on the bearings had caused them to fall […more]

Kitefoiler Tow Test – Feb 2

2/2/11

Another tow test today after Joe and Damon repaired and modified the J-foils. We experimented with different crew weights and different positions for that weight, at various speeds. The adjustments seemed effective–the boat was stable under all parameters.

We put different GPS and tow tension sensors on both the Kitefoiler and Protector this time so that we could compare several sensor options. The load cells on each boat were in general agreement. The GPS receivers often reported different speeds, but this reflects the relative motion of the two boats. The peaks in line tension appear when the speed of the Kitefoiler drops enough for it to drop down from the foils. The segment in the attached graph shows the boats’ […more]