☸️ Wheel Over Point Calculator

Calculate exactly where to apply rudder before a course change, also known as the Wheel-Over Position (WOP) Calculator.

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Course Information

Present Course (°)

Next Course (°)

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Vessel Dynamics

Speed Over Ground

Rate of Turn (°/min)

Head Reach / F (Optional)

From Length (LOA)

Use conservative estimate (1.5 × LOA)

Or Manual Override

Sample Diagram

━━ WOP (Wheel Over Point)━━ Vessel Path-- Track Line

⚙️ How to Use

Step 1: Course Change

Enter your Present Course and Next Course.
Or toggle to enter the Course Change (Δ) angle directly and select Port/Starboard.

Step 2: Vessel Dynamics

Input your Speed Over Ground (SOG).
Input your Rate of Turn (RoT) in °/min.
(Optional) Enter your Length Overall (LOA) or a manual Head Reach (F) distance.

Step 3: Calculate

Press Calculate WOP to find exactly where to apply the rudder before the waypoint.

Note: The primary result is the lead distance (Constant Radius Turn method). This is the distance from the waypoint measured backward along your original course.

📘 Formula Reference

Turning Radius (R):

R = (Speed / RoT) × 0.95493

Wheel Over Point (WOP):

WOP = R × tan(Δ/2) + F

Δ = Course Change angle

F = Head Reach (inertia distance)

0.95493 = Constant derived from 180/(60π)

📖 Terminology

Wheel-Over Position (WOP)

The exact position where the helm order must be given to bring the vessel onto her new course, accounting for turning radius and ship inertia.

Constant Radius Turn (CRT)

A method of turning where the vessel maintains a fixed radius by balancing speed and rate of turn. This is the standard method for precise navigation.

Head Reach (F)

The distance a ship travels forward along its original path from the moment the rudder is applied until the vessel begins to deviate from its course. Often approximated as 1 ship's length (LOA).

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