Cable Logging & Metering Syetem (CLAM)
HistoryA system to monitor various winch and cable parameters was incorporated shortly after the winches were fitted to the ship. The original system was built by Seametrix and replaced in 2002 by CLAM. CLAM was already in use on the RRS Discovery and this enabled a standardisation across all NERC ships.
CLAM was fitted during the 2002 refit period while in Portsmouth. AME staff prepared cabling and interface units to connect to the new hardware.
CLAM has worked well for the last 3 years but AME have been concerned that the hardware platform was obsolete and unsupportable. A total failure of the Oceanlogger, which used the same hardware, during the 2005 Antarctic cruises prompted an investigation into a suitable replacement.
A new platform built on components from Amplicon was installed during the 2000 refit.
Very little of the original CLAM system still exists. Everything except for the electronics unit and interface cards has been supplied/built by AME. The electronics unit is also due to be rebuilt in the near future.
CLAM is purely a monitoring system use to display dynamic parameters such as wire tension (load) and length of deployed cable
CLAM monitors a total of 5 loadcells and 3 optical encoders. The traction winches use a loadcell located between the cable drum and winch to monitor tension (back tension) and another loadcell after the winch to monitor the load on the cable (tension). The third winch (Trawl) is just a drum with a loadcell to monitor cable load. Each system also has an encoder on the cable to monitor the length of deployed cable.
Note that there ar two optical encoders on each outboard system. One is used by CLAM, the other is used by counters on the consoles.
The system can display the following parameters:
- Cable tension
- A graphical representation of tension
- Cable out
- Cable rate
- Back tension (on traction winch systems)
- Water depth (not used)
- Inclinometer.CTD pressure (dbar) or depth (m), (not used)
- CTD altimeter (not used able physical parameters
- Time and date.Alarms for various parameters
- Maximum peak tension
- Near Surface, this alarm sounds when the end of the cable is a specified distance from the surface
- Minimum outboard tension (only with a traction winch system)
- Maximum back tension (only with a traction winch system)
- Minimum back tension (only with a traction winch system)
- The system is menu driven and has been designed for easy operations
No operator intervention is required other than responding to alarm signals.