FAQ

Compared to battery-powered crawlers and buoyancy driven devices, the Wirewalker profiler is extremely reliable. The Profiler efficiently harvests energy from the high-frequency end of the surface-wave spectrum, enabling profiling in 1-3 kt wind waves. When conditions are totally “glassed off”, with neither wind waves nor swell, profiling might cease for a time, but these conditions are rare in the ocean (perhaps less so in lakes). When the waves return, profiling is quickly resumed.

The Wirewalker profiles along 3/16” galvanized wire that can be easily moored in coastal waters. For mooring considerations, refer to our Wirewalker Mooring Design technical note in the Knowledge Center.

Deepwater moorings are also possible but may require additional considerations.

While mooring a Wirewalker is common, free-drifting deployments are the forte of the Wirewalker. A drifting Wirewalker becomes a significant force multiplier as it frees the deployment vessel to perform other activities.

The tilt of the Wirewalker profiling wire significantly influences profiler performance. The more-nearly vertical the wire, the more predictably the Wirewalker performs. The weight supplied standard with the Wirewalker is sufficient to guarantee good profiling in most scenarios. In strong currents, more bottom weight can be added; but it should be noted that as weight is increased, the load on the Wirewalker Profiler increases.

Rather the reverse. The Wirewalker derives power from the differential motion between the suspension cable and the surrounding water. This difference increases with increasing distance from the sea surface, as the Wirewalker can harvest power from progressively lower-frequency components of the wavefield.

For deep profiling operations, it is necessary to use floatation that can tolerate high pressure. (Buoyant foam rated to 300m comes standard.) The buoyancy of foam floatation decreases as its pressure tolerance is increased. So deep profiling Wirewalkers require more foam and/or a smaller payload.

Wirewalkers often profile to 500 m, where they tend to make a typical round-trip profile in ~50 minutes. However, with speciality foam, Wirewalkers have been used to profile even deeper.

Maximum deployment endurace is likely to be limited by a sensor payload limitation (such as power, memory, or biofouling) rather than by any aspect of the profiling system itself.

Since the Wirewalker operates on wave-power, we are utilizing a realitively continuous power supply which perpetually drives the profiling. While early models required replacing the profiling wire more often, advances have been made demonstrating that tens-of-thousands of profiles can be made on a single wire. We now have experinece using a single 100m wire for over a full year (which resulted in >32,000 profies).

While the platform uses wave-power, the sensors typically rely on a finite power source such as a battery pack. It's not uncommon for the maximum deployment duration to be dictated by the total power consumed by the sensor suite.

Likewise, many Wirewalker users are looking for a high-resoltuion picture of the water column. This is made possible when the Wirewalker is paired with fast-sampling, high-quality sensors. Therefore, the aquisition of A LOT of data is possible. However, modern sensors continue to become more power efficient and many manufacturers now offer very large memory options.

Finally, even with long-duration low-power sensors, biofouling can become an issue. However, in many profiling scenarios, the instruments experience a large range of temperatures and light levels every few minutes, providing an inhospitable environment for bio-growth. Still, biofouling remains a concern for long-term operations, especially in shallower waters.

Yes! The Wirewalker profiling wire is the same type of insulated wire rope used on traditional inductive moorings; therefore, it’s possible to use an inductive modem to send data to the surface buoy and from there to shore.

Currently, RBR Ltd offers the RBRcervello, a buoy data controller that simply drops in the surface buoy and communicates with an RBR instrument package on the profiler inductively and transmits that data via GSM or Iridium.