Turning Radius or Turning Circle?

Everybody knows what the term turning radius means, but what we are actually referring to, as in Jeff Hemmel’s feature article “Jet Drive vs. Sterndrive,” is the turning circle.

When describing how tightly a boat can make a U-turn, we are measuring the diameter of the circle. As you can see from the diagram, a radius is only one-quarter of the circle. The full turn equals the diameter of the circle the boat would describe if we kept the wheel hard over.

Takeaway: The Boating tech team measures turning circle by using a chart plotter’s track function. We make several turns around a fixed mark like a buoy and then simply measure across the tracks and average the results.