6x Chart Drawing Triangle Ruler compatible Ship Drawing 300mm Large-Scale Triangle Ruler

6x Chart Drawing Triangle Ruler for Ship Drawing 300mm Large-Scale Triangle Ruler Determine longitude on protractor to determine course or bearing The protractor's 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: 6 x Nautical chart drawing triangle ruler Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.