The Long Ranger (WHLR75) ADCP is a self-contained instrument capable of profiling ranges of up to 600 m. It is typically mounted in a sub-surface buoy as shown to the left. The Long Ranger can be deployed autonomously for later data recovery, or (as shown) configured with an acoustic modem enabling real-time telemetry of the deeper current profile obtained from sub-surface moorings.

To site an example, a bottom-mounted, modem-equipped WHLR75 was deployed along with a system suspended from the platform to provide an overall profiling range in excess of 1400 m – these results have been published, and a copy is available below (“Real Time Ocean Current Data from 3000m and Beyond”.)

WHLR75s are frequently deployed in pairs at mid-depth in deep water moorings, oriented such that one looks up and the other down to provide a combined profile of the currents of 1000m or more. Dozens of Long Rangers have been deployed to assist offshore operations.

Relevant Documents:

• “Real Time Ocean Current Data from 3000m and Beyond”; Offshore Engineer, April 2002; by Michael Vogel (Shell Global Solutions USA) and Darryl Symonds (Teledyne RD Instruments, Inc. (Acrobat File).
• “Profiles in Ocean Current Measurements: Long Ranger ADCP”, International Ocean Systems, Jan/Feb 2004.
• “Top to Bottom Profiling for the Offshore Environment”, Ocean News & Technology, March/April 2004.

The Workhorse ADCP is typically deployed in a bottom mounting (shown at top left), surface float or on a subsurface mooring. Thousands of Workhorses have been deployed world wide, in environments ranging from shallow rivers to the deep ocean, and are the de facto world-wide standard for high resolution current profiling. They are capable of one meter resolution over several tens of meters (up to 100 m in many environments), and are particularly helpful wherever high resolution profiles of the currents are required (e.g. the bottom boundary layer affect the BOP, high velocity shears in the thermocline, etc.).

Like the Long Ranger, they can be deployed autonomously for later data recovery, or with an acoustic modem for telemetry of the data in real time if required.

Datasheet:

• Download WH 300 Sentinal ADCP Datasheet
• “Download WH 300 Monitor ADCP Datasheet

The Workhorse ADCP can be configured for the Lowered ADCP (LADCP) application pioneered by oceanographic researchers. In this technique the full water column profile is constructed by combining the shear profiles measured by an instrument with relatively limited range as it is lowered through the water column.

In many deep water operations an ROV is routinely deployed to inspect the riser and other sub-surface structures. Mounting a Workhorse to the ROV or its tether management system to gather data continuously as they are lowered and raised from the bottom and applying this technique will provide a high resolution profile of the full water column with each deployment of the ROV. In addition, the currents near the garage can be measured and considered prior to making any decisions on deploying the ROV from the garage.