Figure 7 : (a,b) Octagons and (c) transect pattern for measuring data quality. Two locations were chosen for the octagon experiments, one in Malangen (a) for sea state 2-3 and one in Austerhola for sea state 4 (b). The largest and smallest octagon patterns were covered while cruising at 9 and 3 knots, respectively, and the others at 5 and 7, such that each side had a 4-minute duration. The full octagon patterns were repeated 3 times per location. (c) The transects in Lyngsfjorden. Each transect was covered while changing the vessel speed in steps of 3, 5, 7 and 9 knots, and while keeping the rpm constant and variable.
