Navman 5605 Manuel D’Utilisation

TRACKER 5505/5505i/5605 Installation and Operation Manual

NAVMAN

Water speed 10 knots

Current 4 knots

Gives a ground speed of 6 knots

10-5-2 Water speed and ground speed

A paddlewheel sensor and a pitot sensor
measure water speed, the boat speed
through the water. A GPS measures ground
speed, the boat speed over the bottom of
the water. If there is a current, then these
speeds will be different, and the log, trip
log, economy and range will be different, as
shown below.

Water speed is better for measuring the
boat’s potential performance, Ground speed
is better for going to a destination because it
takes currents into account. To select a speed
sensor, see section 10-5-1.

When the current is from ahead, ground speed is less than water speed

For this example:
If the boat travels for one hour, uses 3 gallons of fuel per hour and has 50 gallons of fuel left:

Speed

Log

Economy

Range

Using water speed:

10 knots

10 nm

3.3 nm / gal

165 nm

Using ground speed:

6 knots

6 nm

2.0 nm / gal

100 nm

Water speed 10 knots

Gives a ground speed
of about 8 knots

Current 4 knots at 45º

When the current is from behind, ground speed is more than water speed

Water speed 10 knots

Current

4 knots

Gives a ground speed of 14 knots

For this example:
If the boat travels for one hour, uses 3 gallons of fuel and has 50 gallons of fuel left:

Speed

Log

Economy

Range

Using water speed:

10 knots

10 nm

3.3 nm / gal

165 nm

Using ground speed:

14 knots

14 nm

4.7 nm / gal

235 nm

Current 4

knots at 45º

Gives a ground speed of about 13 knots

Water speed 10 knots