Determine Wheel Over Point (WOP): 3 Methods for Accurate Ship Turns ll Rate of Turn (ROT)
Summary
TLDRThis video provides a detailed guide on how to manually determine the wheel over point for altering a ship's course. It covers three different methods, starting with using an arc centered on a reference point like a lighthouse, followed by using parallel index lines without a reference point, and finally, a calculation-based approach. Each method is explained with step-by-step instructions, ensuring precise navigation and avoiding overshooting or undershooting the intended course. The video is useful for mariners needing to manually plan course changes, emphasizing safety and accuracy.
Takeaways
- đ **Wheel Over Point:** The specific point along the planned track where the helm must be executed to alter the ship's course to the next intended direction.
- â **Purpose:** Ensures the ship begins its turn at the right moment to achieve the desired new course without overshooting or undershooting the target.
- đłïž **Factors Considered:** Ship speed, turning radius, rate of turn, and the angle of the intended course change are crucial in determining the wheel over point.
- đ **Method 1:** Plot an arc or circle with the lighthouse at the center and a radius of one nautical mile. This helps to maintain the desired distance while turning.
- đ§ **Turning Point:** Draw a perpendicular line from the lighthouse to the planned track to find the turning point where the ship starts to turn.
- đ **Method 2:** Use parallel index lines on both tracks with the chosen radius to determine the wheel over point without a fixed reference point.
- đ **Calculation:** Find the course difference, ship's rate of turn, time run, distance run, and reaction distance to calculate the wheel over point accurately.
- âïž **Rate of Turn:** Determined by dividing the ship's speed by the turning radius, providing a rate in degrees per minute.
- â±ïž **Time Run:** The time it takes for the ship to turn from the turning point to the end of the turn, calculated by dividing the course difference by the rate of turn.
- đ **Distance Run:** The distance the ship travels during the turn, found by multiplying the ship's speed by the time run.
- đșïž **Reaction Distance:** Distance from the waypoint to the turning point, helping to pinpoint the exact wheel over point location.
Q & A
What is the 'wheel over point' in ship navigation?
-The 'wheel over point' is the specific point along the planned track where the ship's helm must be executed to alter the ship's course to the next intended direction. It ensures that the ship begins its turn at the right moment to achieve the desired new course without overshooting or undershooting the target.
What factors need to be considered when determining the wheel over point?
-The factors to consider when determining the wheel over point are the ship's speed, turning radius, rate of turn, and the angle of the intended course change.
How does one determine the wheel over point using the first method described?
-In the first method, an arc or circle is drawn with the lighthouse at the center and a radius of one nautical mile. The planned route is then transferred along this arc. The wheel over point is found by measuring a distance of one ship's length backward from the turning point along the planned track.
What is the significance of the turning point in the process of altering a ship's course?
-The turning point is the location along the planned track where the ship starts to respond to the helm execution and physically begins to turn. This point is crucial in determining when to execute the turn to achieve the desired course alteration.
Why is it important to account for the ship's length when determining the wheel over point?
-Accounting for the ship's length is important because it takes time for the rudder to react before the ship starts to turn. Therefore, an allowance of about one ship's length is given to ensure that the turn begins at the right moment.
What is the second method for determining the wheel over point, and how does it differ from the first method?
-The second method involves drawing parallel index lines on both tracks at a chosen radius. The intersection of these lines serves as a reference point. The wheel over point is then determined by measuring one ship's length backward from the turning point along the initial planned track. This method differs from the first in that it does not require a fixed reference point like a lighthouse.
How is the ship's rate of turn calculated?
-The ship's rate of turn is calculated by dividing the ship's speed by the turning radius. The result gives the rate of turn in degrees per minute, which indicates how quickly the ship can change its course.
What is the purpose of calculating the time run and distance run in the third method?
-The time run is the time it takes for the ship to complete the turn, while the distance run is the distance traveled by the ship during the turn. These calculations help determine the reaction distance and the exact location of the turning point, which are essential for accurately finding the wheel over point.
Why might the third method be particularly useful when communicating with port authorities?
-The third method, which involves calculations based on the ship's speed, turning radius, and rate of turn, is useful for providing precise and detailed information. This can be helpful when discussing navigational details with port authorities or when precise documentation is required.
How do the three methods compare in terms of determining the wheel over point?
-All three methods ultimately lead to the same location of the wheel over point. The first method uses a fixed reference point like a lighthouse, the second method uses parallel index lines without a fixed reference point, and the third method involves detailed calculations. Despite their differences, they all yield consistent results.
Outlines
â Understanding the Wheel Over Point
The first paragraph introduces the concept of the wheel over point, which is crucial for altering a ship's course accurately. It explains the purpose of the wheel over point, emphasizing its role in ensuring the ship turns at the correct moment to achieve the desired course without deviation. Key factors such as ship speed, turning radius, rate of turn, and course change angle are considered. The paragraph also mentions that the wheel over point can be determined manually or with an Electronic Chart Display and Information System (ECDIS), and the video will demonstrate the manual method.
đ§ Method 1: Plotting the Wheel Over Point Using a Lighthouse
The second paragraph details the first method of determining the wheel over point, using a plotted arc with a lighthouse as the reference point. The method involves measuring distances using the latitude scale, transferring the planned route along the arc, and identifying the turning point where the ship starts to turn. The wheel over point is calculated by measuring a distance equivalent to the ship's length in nautical miles before the turning point. This method serves as a guide, with a recommendation to refer to the ship's safety management system for specific procedures.
đ Method 2: Using Parallel Index Lines for Wheel Over Point
In the third paragraph, the second method for determining the wheel over point is discussed, using parallel index lines. These lines are drawn on both tracks with the distance between them equal to the chosen turning radius. The intersection of these lines serves as the reference point, similar to a lighthouse in the first method. The turning point is identified by drawing perpendicular lines from the reference point to the planned track. The wheel over point is then calculated by measuring the ship's length in nautical miles backward from the turning point along the initial track. This method is compared with the first, showing that both yield the same result.
đ Method 3: Calculating the Wheel Over Point
The final paragraph describes the third method, which involves calculating the wheel over point using a mathematical approach. The method begins by determining the course difference between the initial and final courses, followed by calculating the ship's rate of turn using speed and radius. The time taken for the turn and the distance run during the turn are then computed. The reaction distance, or the distance from the waypoint to the turning point, is found by dividing the distance run by two. Finally, the wheel over point is determined by measuring the ship's length in nautical miles backward from the turning point along the initial track. The paragraph concludes by confirming that all three methods produce the same wheel over point.
Mindmap
Keywords
đĄWheel Over Point
đĄTurning Point
đĄPlanned Track
đĄRadius
đĄRate of Turn
đĄReaction Distance
đĄHelm
đĄNautical Mile
đĄPerpendicular Line
đĄLighthouse
Highlights
Explanation of the wheel over point as the specific location on the track where the helm must be executed to change the ship's course.
Discussion on the importance of determining the wheel over point to avoid overshooting or undershooting the intended course.
Factors affecting the wheel over point: ship speed, turning radius, rate of turn, and the angle of the intended course change.
Introduction of three different methods to manually determine the wheel over point, starting with a method involving plotting an arc or circle with the lighthouse at the center.
Method 1: Using the latitude scale to measure distance and draw an arc for the ship to follow when altering course.
Explanation of how to transfer the previously planned route along the arc to maintain a 1 nautical mile distance from the lighthouse.
Detailed steps on finding the turning point and determining the wheel over point by measuring the ship's length in nautical miles.
Method 2: Using parallel index lines and a reference point without needing a physical landmark like a lighthouse.
Comparison of Method 1 and Method 2, showing that both methods lead to the same wheel over point, whether a fixed reference point is available or not.
Introduction of Method 3, which involves more calculation and might be useful when discussing with port authorities.
Step-by-step guide on calculating the course difference, rate of turn, and time run in Method 3.
Explanation of how to determine the reaction distance and distance run during the turn in Method 3.
Demonstration that all three methods result in the same location for the wheel over point.
Emphasis on checking the pilot card for the ship's maneuvering characteristics when selecting the desired radius during course alteration.
Final reminder to refer to the company's safety management system (SMS) manual for official procedures on determining the wheel over point.
Transcripts
wheel over point is the specific point
along the plan track where the helm must
be executed to alter the ship's course
to the next intended
Direction the purpose of wheel overo is
to ensure that the ship begins its turn
at the right moment to achieve the
desired new course without overshooting
or undershooting the target there are
factors to be considered to determine
the wheel over Point those are the ship
speed turning radius rate of turn and
the angle of the intended course change
this might be easy if you are using an
ectis in making a passage plan but in
today's video I will show you how to
determine the wheel over Point
manually assuming that this is your
planned route when a beam of cura point
the ship will alter course 050 ° with an
approaching course of 350°
true you've been advised by the captain
to move the plan track closer to a
lighthouse and maintain a distance of 1
nautical mile from the lighthouse while
the ship is turning to the next course
then determine the wheel over
point the ship's length overall is 280 M
with an average speed of 12
knots this video shows three different
methods on how to determine the wheel
over
point the first method is to plot an arc
or a circle where the lighthouse is at
the center with a radius of one nautical
mile the actual position of the
lighthouse is marked with a small small
circle at the base of the
symbol use the latitude scale to measure
the
distance as we know 1 minute of an arc
in the latitude scale is equal to 1
nautical
mile this latitude scale May differ from
the actual chart it is just made for the
purpose of this
video this Arc will be the track to be
followed by the ship when altering
course from 350° to 050 ° true in order
to maintain a one nautical distance
while turning to the next
course we will now transfer the
previously planned route along the
ark both tracks should be touching the
edge of the drawn
Arc we have now a clear view of where
the ship starts to turn and to where it
ends but we need to determine the exact
point draw a line from the
lighthouse this line should be
perpendicular to the plan track do this
on both
tracks this point where the
perpendicular line intersects with the
plan track is the turning point or
transfer
point this point along the plan track is
where the ship starts to respond from
the executed Helm and physically begins
to turn this point is not a wheel over
point on the other side where the
perpendicular line intersects with the
plan track is the point where the ship
ends its turn and continues to its new
course the wheel over Point can be found
about a ship's length before the turning
point so if the ship's length is 280 M
we need to convert it into a nautical
mile so that we can use the latitude
scale to measure 280 M before the
turning point to convert it 280 /
1,852 we divide it by 1852 because one
nautical mile is equal to
1,852
M the ship's length in nautical mile is
0.151 use the latitude scale to measure
0.151 this distance is
0.151 as shown on the
scale measured the distance from the
turning point along the plan
track this point is now our wheel over
point in this scenario when we reach the
wheel over point point we will execute
Helm to
starboard for bigger ships it takes time
for a Rudder to react before the ship
will start to turn so we give an
allowance of about a ship
length this method serves only as a
guide if you are on board kindly refer
to the company's safety management
system or SMS manual on how to determine
the wheel over
Point How about if there is no reference
point how can we determine our will over
point
this is the second method I will discuss
in this video on how to determine the
wheel over
point I will use the same length overall
speed radius and the plan tracked on the
same spot so that we can compare this
later on from the first
method first draw parallel index lines
on both
tracks these lines should be in the
inner part of the
turn the distance should be the chosen
radius in this scenario our radius is 1
nautical
mile for a smaller ship you can use a
smaller
radius for a much bigger ship you can
use a radius greater than 1
mile kindly check the maneuvering
characteristics of your ship on board
including the turning
radius once the parallel lines are
drawn the intersection of these line
serves as your reference point just like
a lighthouse in the previous
method if we draw an arc or a circle
with one nautical mile radius where the
intersection of the parallel index lines
will be at the center this is what it
looks like but I will not use this Arc
in this method assuming that you do not
have a compass divider on hand so let us
take it
out next we will determine the Turning
Point draw a perpendicular line on the
plan track intersecting the assumed
reference point which is the
intersection of the two parallel index
lines do this on both
tracks this point where the
perpendicular line intersects with the
initial track is the turning
point this is the point where the ship
starts to turn if the helm is executed
at the wheel over
point on the other side where the
perpendicular line intersects at the
plan track is the the point where the
ship ends her turn and proceeds to her
new
course the distance from this point to
this point is called reaction
distance the wheel over Point can be
found about a ship's length before the
Turning
Point the ship's length in nautical mile
is
0.151 so measure
0.151 nautical mile from the Turning
Point going backward along the initial
plan track
this point will be our willover
Point upon reaching this point execute
Helm to starboard the ship will start to
turn when she arrives at the Turning
Point let us compare this method to the
first method I have previously
discussed the two parallel index lines
intersect at the Lighthouse position
which serves as our reference point in
the second
method the turning point is at the same
spot as with the previous method so as
with the the wheel over point so whether
we have a fixed reference point or none
we can still determine our wheel over
Point manually based on our preferred
radius using the two parallel index
lines but kindly check the pilot card on
board for the maneuvering
characteristics of your ship so that you
can choose the desired radius during the
course
alteration the third method is more on
calculation this method might be useful
if you've been asked by some Port
Authorities
you can discuss it with him even on a
piece of paper I will use the same given
from the previous method with the same
plan track so that we can compare it
with the previous
method first we need to find the
difference between the initial and final
course the final course is 050 ° minus
the initial course which is
350° the course difference is 0
60° before you can subtract these two
add 3 60° to 050
° so we have now 410 -
350 the difference is
060 next we will find the ship's rate of
turn the formula is ship speed divided
by
radius the given speed is 12 knots but
remember that when the ship turns the
speed
reduces we will assume that that during
the turn the ship's average speed is 10
knots divided by the radius which is 1
nautical mile the rate of turn is 10°
per
minute supposed to be the rate of turn
is 10 hours if we examine the existing
units to convert it into degrees per
minute multiply it by 180 / Pi the value
of 180 / Pi is
57.3 so we have 10 hours *
57.3 to convert hours into minute we
will divide it by 60 since 1 hour is
equal to 60
minutes but usually we do not do this
procedure because if we look at the
value of 57.3 and the divisor which is
60 we can both cancel these
values the slight difference in the
value if we go through the procedure is
negligible when we are in the actual
maneuvering so just divide the ship
speed and the desired radius will give
you a rate of turn and the unit is in
degrees per minute I will make a
separate video with a detailed
explanation of how to determine a rate
of turn in this illustration we just
draw an arc assuming this is the ship's
track during the
turn this calculation will lead to the
exact location of the Turning
Point next we will determine how long it
takes for a ship to turn from the
turning point and until the end of the
turn known as the time run we will just
divide the course difference and the
rate of
turn so 60 / 10 the time run is 6
minutes or 0.1
hour we need to convert it into an hour
because we need it later on to convert
into an hour divide 6 minutes by 60
since in 1 hour is equal to 60
Minutes next we will determine the
distance traveled by the ship from the
point she starts to turn until the turn
ends known as distance run distance run
is equal to ship speed which is 12 mph
times the time run which is 0.1 hour the
distance run during the turn is 1.2
mil next we will determine the reaction
distance this distance is from the
Waypoint to the Turning
Point reaction distance is equal to
distance run divided by two which is
equal to 0.6
mile now measure 0.6 mile from Waypoint
to both sides of the
track this point now will be your
turning
point and on the other side this is the
point where the turn
ends use the given speed in calculating
the distance run which is 12 knots
because we will be measuring the
distance along the Waypoint not along
the Turning
Circle to determine the wheel over over
point we will use the ship's
length from the turning point measure
0.151 nautical mile going backward along
the initial
track this point is the wheel over point
if we check the reaction distance in our
previous method it is also 0.6 nautical
mile these three methods give the same
location of the wheel over Point that's
all for now I hope you find this video
helpful thank thank you for watching bye
Voir Plus de Vidéos Connexes
Parallel Indexing: How to Determine & Set Parallel Index Lines l PI Lines l RADAR l Passage Planning
Linear Equations - Algebra
Linear Functions
Slope, Line and Angle Between Two Lines |Analytic Geometry|
Distance from a Point to a Line and Distance Between Parallel Lines |Analytic Geometry|
Como instalar e usar o Mendeley
5.0 / 5 (0 votes)