Speed through water value is not accurate across range of boat speeds

[Chuck - Raymarine - Moderator]

Speed through water value is not accurate across range of boat speeds

As speed through water sensors have non-linear error associated with them, greatest speed through water accuracy will be achieved with instruments supporting multi-point speed calibration (ex. i70/i70S Multifunction Instrument Displays, etc.) in contrast to instruments and fishfinding products supporting single point speed calibration (ex. i40 Speed/Bidata, i50 Speed/Tridata Instruments, ax7/cx7/e7D/ex7/eSx7 MFDs, CP370, etc.). Should a product supporting single point speed calibration be the system's speed through water source, then speed will be most accurate when the boat's actual speed through water matches that which the instrument was calibrated at. Accordingly, should the vessel be used in a performance manner (ex. racing, etc.), then it would be recommended that an i70/i70S Multifunction Instrument w/iTC-5 Analog Instrument Converter be interfaced to the speed through water transducer. Should the vessel be used in more leisure oriented manner (ex. cruising, day sailing, etc.), then it would be recommended that product supporting single point speed calibration be interfaced to the speed through water transducer.

Speed sensing instruments should be calibrated per the instructions found within the respective instrument's Installation and Operation Guide. Should a fishfinding product be the source of speed through water data, then speed offset will be configured via the fishfinding product's settings (ex. from within the Fishfinder application of a/c/e/eS/gS-Series running LightHouse II software, the command sequence is MENU->SET-UP->TRANSDUCER SET-UP->SPEED OFFSET).

RAYFAQ#