Determine longitude on protractor to determine course or bearing
The protractor's vertex allows placing a dividing point or pencil on a point of the hole
A string can be used to fix the stopwatch used on the hole for a long distance of course.
When charting, it is used to draw the bearing line or heading line, and measure the bearing line or heading degree.

colour:Transparent
Material:plastic
size:300mm

Package Contents:
4*Nautical chart drawing triangle ruler