Captain Bob's Dial A Sail & Easy True Plotter

Instructions & Questions


“Easy Plot and Know the Point of Sail”


Ø      First find the wind direction from the Ships Compass when raising the main sail.  Confirm it with the weather report you obtained from the weather service.  Rotate the wheel to the wind direction on the Compass Rose.


Ø      Wind directions are magnetic and are the direction from which the wind is coming.  To calculate the wind directions relative to True North add/subtract Variation.  Wind speeds are given in knots.


Ø      When you have established the wind direction, Dial A Sail will show the Point of Sail you want to obtain and give the compass degrees necessary to steer to be on that Tack and point of Sail.  Adjust the sails for this point of sail.


Ø      It provides the compass degrees for each point of sail on Port or Starboard Tack.  Knowing the point of sail provides the knowledge for sail trim.


Ø      Dial-A-Sail will provide the running degrees of the danger area to prevent accidental jibbing.


Ø      Compare the heading you want to steer with the Dial-A-Sail, to know what tack and point of sail you will have to be on and the tacks necessary to maintain your rhumb line.  Dial A Sail makes it easy to plan you sail from home using the current weather report.


Ø      If the rhumb line course is in the “no-sail-zone” it will show the tacks necessary to reach your destination.


Ø       Apparent wind is a combination of the true wind plus boat speed.  Sails are trimmed to the Apparent wind, but boat performance is best with reference to the true wind.


Ø      Improve teamwork between the helmsman and the sail trimmers to adjust sail trim to achieve maximum boat speed on each heading.


The Winds are from the S.E.

The Rhumb line is 155* PSC

What will the compass read on
the tacks necessary to get there?

What are the Points of Sail?


The winds are from the N.E.

What is the Compass reading for the accidental jib area?

What would be a safe heading on each tack?




The wind is out of N.E.

What will the compass read on a Port Tack Close reach?

Starboard Tack close reach?




Your compass reads 330*.

The winds are from the E.

What tack and point of sail are you on?




True Plotter
Place center of the True Plot on any known position.  Place North in Proper direction per Chart Lines.

Align any vertical or horizontal line on the True Plot with any latitude or longitude on the Chart.

 Extend the string plotter in the direction of Travel.

Read the True course from the True Plot. 

To calculate magnetic add – subtract Variation.

For a Bearing plot, remember:  Bearing object is "from" object,  so use the reciprocal.  (Shown on the True Plot) 

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