36 last one
TRANSCRIPT
-
8/8/2019 36 last one
1/27
Navigation
NAU 102
Lesson 36
-
8/8/2019 36 last one
2/27
Vessel Grounding
-
8/8/2019 36 last one
3/27
-
8/8/2019 36 last one
4/27
Magnetic Compasses
Disadvantages
Deviation
No digital output
-
8/8/2019 36 last one
5/27
Gyrocompasses
Disadvantages
ExpensiveDifficult and expensive maintenance
Requires stable power and backup
Takes a long time to stabilize
-
8/8/2019 36 last one
6/27
New Advances
Flux Gate Magnetic Compass
Ring Laser Gyrocompasss
No moving parts
Digital output
Low power requirements
Rapid start-up
Self correcting
-
8/8/2019 36 last one
7/27
FluxGate Compass
Two harmonic coils wrapped around a
magnetic core.
Earths magnetic field changes the coresmagnetic induction.
The coils sense the changes.
Electronics calculate the magnetic field
necessary to cause the change.
-
8/8/2019 36 last one
8/27
FluxGate Compass
To minimize deviation, the sensor is
placed at the top of the mast.
Residual deviation is automatically
calculated as the ship changes course 360.
It makes its own deviation table!
Deviation is automatically applied.
-
8/8/2019 36 last one
9/27
FluxGate Compass
Operator can input the variation.
Resulting true direction is sent to digital
equipment.
-
8/8/2019 36 last one
10/27
Ring LaserGyrocompass
Two laser beams travel in opposite
directions around a fiber-optic ring.
When the compass (the ship) isntturning, the beams are in phase.
When the compass turns, the beams are
out of phase.
The quicker the turn, the larger the phase
differences.
-
8/8/2019 36 last one
11/27
Ring LaserGyrocompass
-
8/8/2019 36 last one
12/27
Exam Review!
A ship is proceeding on course 240 ata speed of 18 knots. The apparentwind
is from 040 relative at30 knots. What
is the true wind.
True Wind Calculation
-
8/8/2019 36 last one
13/27
Wind
Step 1: Plot ships course& speed.
-
8/8/2019 36 last one
14/27
Wind
Step 2: Convert relative direction of
apparent wind to true direction, if necessary.
A ship is proceeding on course 240 ata speed of 18 knots. The
apparentwind is from 040 relative at30 knots.
R + S = T
040 R + 240 = 280 T
-
8/8/2019 36 last one
15/27
WindStep 3: Draw the apparent wind from the tip of the
ships course & speed vector.
(Remember, draw the direction the wind is blowingtowards!)
-
8/8/2019 36 last one
16/27
WindStep 4: Complete the triangle. Result = True wind.
Direction = 315 T
Speed = 20 knots
-
8/8/2019 36 last one
17/27
Slip
The propeller on a vessel has a
diameter of 24.6 feet and a pitch of
26.1 feet. What would be the
apparent slip if the vessel cruised 462
miles in a 24 hour day at an averageRPM of 72?
-
8/8/2019 36 last one
18/27
Slip
The propeller on a vessel has a diameter of 24.6 feet
and a pitch of 26.1 feet. What would be the apparent
slip if the vessel cruised 462 miles in a 24 hour day at
an average RPM of 72?
Distance = Pitch x RPM x Time (in minutes) x Efficiency
6080 feet/nm
-
8/8/2019 36 last one
19/27
Slip
The propeller on a vessel has a diameter of 24.6 feet
and a pitch of 26.1 feet. What would be the apparent
slip if the vessel cruised 462 miles in a 24 hour day at
an average RPM of 72?
462 nm = 26.1 ft x 72 RPM x (24 hr x 60 min/hr) x Efficiency
6080 feet/nm
Efficiency = 1.038 (103.8%)
-
8/8/2019 36 last one
20/27
Slip
The propeller on a vessel has a diameter of 24.6 feet
and a pitch of 26.1 feet. What would be the apparent
slip if the vessel cruised 462 miles in a 24 hour day at
an average RPM of 72?
Slip = 100 - 103.8% = -3.8%
Slip = 100% - Efficiency
-
8/8/2019 36 last one
21/27
FuelConsumption
While steaming at 19.5 knots your
vessel burns 297 barrels of fuel perday. What will be the rate of fuel
consumption if you decrease speed to
15 knots?
-
8/8/2019 36 last one
22/27
FuelConsumption
While steaming at 19.5 knots your vessel burns 297
barrels of fuel per day. What will be the rate of fuel
consumption if you decrease speed to 15 knots?
New Consumption = New Speed3
Old Consumption Old Speed3
-
8/8/2019 36 last one
23/27
FuelConsumption
While steaming at 19.5 knots your vessel burns 297
barrels of fuel per day. What will be the rate of fuel
consumption if you decrease speed to 15 knots?
New Consumption = 153
297 barrels 19.53
New Consumption = 135 barrels
-
8/8/2019 36 last one
24/27
FuelConsumption
Your vessel has sufficient fuel to
steam 812 nm at 15 knots. At whatspeed must you proceed to reach your
next port, 928 miles distant?
-
8/8/2019 36 last one
25/27
FuelConsumption
Your vessel has sufficient fuel to steam 812 nm at 15
knots. At what speed must you proceed to reach your
next port, 928 miles distant?
New Consumption = New Speed2 x New Distance
Old Consumption Old Speed2 x Old Distance
-
8/8/2019 36 last one
26/27
FuelConsumption
Your vessel has sufficient fuel to steam 812 nm at 15
knots. At what speed must you proceed to reach your
next port, 928 miles distant?
x nm = New Speed2 x 928 nm
x nm 152 x 812 nm
14.03 kts = New Speed
-
8/8/2019 36 last one
27/27
Introduction to Navigation
Questions?