Q.How to mark a Wheel Over Point on chart ?

So lets say you have courses drawn on chart and for some course alteration you want to calculate the wheel over point.

For that you need to calculate the turning radius, that can be found by SOG/ROT

1. Let's say your ship is doing 14 knots and your R.O.T is also 14 deg/min. Turning radius = SOG/ROT , that is 1.0 NM.
2. Now, lay two lines parallel to both the initial course and final course with a distance of Turning Radius i.e 1NM between them.
3. Mark the point where the two lines intersect.
4. Now with the help of compass and with radius equal to Turning radius which is 1.0 NM. Draw an arc onto your initial course, such that the course line would be tangent to the arc drawn at some point.
5. Mark this point. But, hey ! You didn't get your wheel over point yet. But you are almost there.
6. Now you know the ship is a very large machinery, it doesn't react at once and every vessel has its own characteristics of maneouvere and It will take some time to react to the helm. So,here we have to consider the excution point wherein the ship actually starts to turn. This can be found out from the wheelhouse poster of your ship. For calculation purpose here, we take the Point of overcoming the inertia as 0.3 NM. (This will be different for different ship, please refer your ships maneouvering characteristics)
7. Your wheel over point is 0.3 NM (point of overcoming the inertia) backward from the point where your course became tangent with the arc.

That's it ! That's how you get your wheel over point.

Hope this helps !