Appendix C - Speed Through Water And Over Ground - Navman FUEL 3100 Manual De Instalación Y Funcionamiento

Appendix C - Speed through water and over ground

Different instruments measure different boat
speeds. A paddlewheel sensor measures
boat Speed Through the Water (STW). A GPS
measures boat Speed Over the Ground, ie
over the bottom of the water (SOG). If there
is a current, these speeds will be different, as
When the current is from ahead, speed over ground is less than speed through water
When the current is from behind, speed over ground is more than speed through water
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explained below. Therefore, the readings for
speed, log, trip log, economy and range will
depend on whether the speed input is STW or
SOG and if the current
is constant.
NAVMAN
FUEL 3100 / DIESEL 3200 Installation and Operation Manual