High quality heave measurements based on GPS RTK and accelerometer technology

Accurate heave measurements are important in many applications to compensate for vessel wave motion, e.g. in hydrographic seabed mapping, dredging, and offshore crane heave compensation. The accuracy is often specified to be better than the larger of 5 cm and 5% relative. And with more and more accurate echo sounders and attitude sensors, there will be a demand for even more accurate and robust heave sensors in the future. This paper discusses several methods, both on-line methods for real-time heave computation and off-line methods for post processing. It will also treat two different technologies. Heave can be computed from GPS RTK height measurements and from vertical accelerations measured by linear accelerometers. Integrated solutions that combine these two technologies are also discussed.