Sea Trial Check - Furuno CI-68 Installation Manual

4. ADJUSTMENTS
4.6

Sea Trial Check

4.6.1 Ship's speed test
Do the milepost test where ground tracking measurement can be done.
1. Reset the distance run at the moment the milepost test is initiated.
2. Read the distance run at the moment the milepost test is initiated.
3. Calculate true ship's speed (1) from the data of the milepost test and ship's speed
of the CI-68 from that of the distance run (2).
4. If the error between (1) and (2) is more than ± (1%+0.1 kn), correct it referring to
the [GT SPD CALIB] on page 4-3. Calibrating is not necessary when the error is
within ± (1%+0.1 kn).
5. Repeat the milepost test several times. Record the data in Table 1.
6. Record the ship's speed every 10 seconds in table 2.
7. Calculate the average ship's speed from the data in the Table 2 to compute accu-
racy.
4.6.2 Current data check
Use the ground tracking mode to record the current (tide) data.
1. Run your boat following the square
course shown below. Each side of the
square is about 1 mile in length.
2. Record the ship's speed and tide data
every 30 seconds in table 3.
3. On a separate piece of paper, plot the
current speed and direction based on
the table 3. Confirm that the current
reading is stable in any ship's heading.
(Only when the current changes mini-
mally while the ship runs square
course.)
Confirm that the currents orient the same direction. If not, the interference from other
equipment, air bubbles and noise may be present. Also, take into account that inter-
ference from air bubbles may occur since there is no load in the milepost test.
Note: When a bearing sensor is connected in lieu of a gyrocompass, accurate mea-
surement of current direction is not expected because the bearing data itself is in error.
Note that it is difficult to distinguish this unit reading when the above test is done where
the current is complex.
4-14
Ship's route:
Advance
straight 1
mile approx.
Current
Ship's route