Wirewalker: An autonomous wave-powered vertical profiler

An inexpensive vertically profiling float that draws its energy from the ocean surface wavefield is described. Termed the "Wirewalker,'' it is a generalized platform capable of supporting a variety of self-contained instruments. The motion of the waves drives the positively buoyant profiler downward. It then free floats upward, decoupled from the surface motion field. The design focuses on mechanical simplicity and low cost. In moderate sea states, a prototype Wirewalker has completed profiles to depths of 60 m every 15 min. Profiles from the surface to 50-100 m can be obtained rapidly enough that diel and higher-frequency variability can be resolved.