Determine Wheel Over Point (WOP): 3 Methods for Accurate Ship Turns ll Rate of Turn (ROT)

Summary

This 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

• 📍 **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.
• ⚓ **Purpose:** Ensures the ship begins its turn at the right moment to achieve the desired new course without overshooting or undershooting the target.
• 🛳️ **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.
• 📏 **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.
• 🧭 **Turning Point:** Draw a perpendicular line from the lighthouse to the planned track to find the turning point where the ship starts to turn.
• 📐 **Method 2:** Use parallel index lines on both tracks with the chosen radius to determine the wheel over point without a fixed reference point.
• 📝 **Calculation:** Find the course difference, ship's rate of turn, time run, distance run, and reaction distance to calculate the wheel over point accurately.
• ⚙️ **Rate of Turn:** Determined by dividing the ship's speed by the turning radius, providing a rate in degrees per minute.
• ⏱️ **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.
• 🔍 **Distance Run:** The distance the ship travels during the turn, found by multiplying the ship's speed by the time run.
• 🗺️ **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.