We towed Quadfoiler and Stiletto with a 35 foot protector RIB.
Quadfoiler and Stiletto, Speed vs. Load Comparison
We instrumented the Quadfoiler and Stiletto boats with a GPS receiver and towed them with a line attached to a load cell. Each boat was first towed directly behind the power boat, then towed while steering so the towed boat was 30-45 degrees away from the center of the wake. The length of the tow line was approximately 40 meters. The plots below show speed vs. load for each towed boat. The red points indicate periods during which the test boat was being pulled directly behind the power boat, while the green points show data recorded while the test boat was being steered not to follow directly behind.
1. The Stiletto load appears to increase exponentially with speed, while the Quadfoil’s rate of load increase diminishes significantly as the foils take effect at 10+ knots.
2. The effect of the foils on the towing load appears to vary significantly, depending on factors that we did not measure in this experiment. For example, we made many adjustments to the weight distribution on board the boat and to the angle of the line towing the boat.
1. To capture more aspects of the system under test, all future experiments will instrument both boats with GPS and record the towed boat’s attitude using an IMU. The tow point should also be recorded.
2. Any particularly surprising results from the test should be verified against recorded video. In particular we may wish to isolate cases of relatively high and low loads and identify the causes by looking at the video documentation.