Navigation

The suite of instruments is different on each ship. The table below provides the relevant details.

Ship	Navigation instrument suite	Comments
RV Plymouth Quest	Instrumentation suite specification is not yet available
RV Prince Madog	Instrumentation suite specification is not yet available
RRS James Clark Ross	Three GPS receivers: a Trimble 4000, a Ashtech ADU-2 and a GLONASS (Ashtech GG24). James Clark Ross is also equipped with a Sperry Mk 37 Model D Gyrocompass, a Chernikeeff Aquaprobe Mk V Electromagnetic log and a Sperry SRD 421 Doppler log.	In addition to the instruments, a Racal Satcom receives GPS SV range correction data via INMARSAT B: this is passed to the Trimble and other GPS receivers to allow them to operate in differential mode (DGPS). The Trimble 4000 in differential mode is normally the primary source of positional information while the data stream from the gyrocompass constitutes the most continuous information available on ship's heading. It is involved in processing data from meteorological instrumentation (so as to derive information on true wind velocity).
RRS James Cook	Instrumentation suite specification is not yet available
RRS Discovery	Three GPS receivers: a Ashtec G12, a Trimble 4000, and a Glonass. Discovery is also equipped with a Chernikeef electro-magnetic Speedlog velocity data and Gyrocompass.