Raymarine i50 Depth Installation And Operation Instructions Manual page 60

1 point speed calibration
The instrument display's speed readings can be
calibrated using a 1 point calibration process, in most
situation this is all that will be required to calibrate
our speed readings.
Prerequisites:
• For best results SOG data should be available, or
an alternative method of estimating vessel speed
must be used (e.g. vessel speed can be estimated
using Nautical Measured Mile Markers
landmarks of a known distance apart).
• You will need to be underway, with sufficient space
to maneuver unhindered.
• In order to achieve accurate results, water
conditions must be calm with zero tide and zero
current.
From the User Calibration Menu:
1. Steer your vessel on a steady course at a
constant typical speed.
2. Press the Speed button until 1 of the Current
Speed pages is displayed (4 presses from the
User Calibration entry page).
If SOG data is available over SeaTalk
the SOG page is displayed, if SOG data is not
available then the Calibration Factor page is
displayed.
S pe e d
S pe e d
3. If the SOG page is displayed and the water
conditions are acceptable, press and hold the
Reset button for approximately 3 seconds to
accept SOG as the current log speed.
50
45
Re s e t
40
4. Alternatively, with the Calibration Factor page
displayed use the Trip and Reset buttons to
adjust the calibration factor until the displayed
speed matches your estimated speed.
The default calibration factor is 1.00. The
calibration factor can be set from 0.25 to 2.50.
5. If SOG is available you can switch between the
Calibration Factor and SOG pages by pressing
the Trip and Reset buttons at the same time.
Note: To exit the User Calibration pages at any
time, press and hold the Depth and Speed buttons
at the same time for approximately 2 seconds.
60
or similar
ng then
60 5
55
3 10
15
20
35 25
30
Trip Re s e t
Nautical measured mile markers
When neither SOG data or any other reliable means
of estimating Speed Through the Water (STW) is
available, Nautical Measured Mile Markers can
be used to help calibrate Log Speed. Nautical
measured mile markers are identified by two pairs of
posts or towers. The distance between each pair of
markers is 1 nautical mile.
Each marker in a pair is separated by distance and
elevation from its partner. The front marker is closer
to the water and shorter than the marker behind it.
Markers — side view
1. Front marker
2. Rear marker
When the 2 markers appear vertically aligned
the vessel is on the correct range line to begin a
measured mile run.
Marker alignment
1
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1. Left of range line
2. On range line
3. Right of range line
The vessel should already be at top speed and as
the first pair of markers appear aligned a stopwatch
should be started, when the vessel passes the
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second pair of aligned markers the stopwatch is
stopped.
Measuring a nautical mile
1
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1. Starting point (start stopwatch)
2. Measured mile
2
1
2 3
2
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