Here’s some great advice from Skipper Tips about how to read a chart – electronic or paper – showing numbers, including some with underlines or enclosed by parentheses. Here’s how to read these symbols to keep off the rocks and navigate safely: Nautical datums are stated in two ways. Look in the title block area (that area of a chart just beneath the title) to the “Chart Datum”, or soundings (depths). These will be stated as feet, fathoms, meters or a combination such as fathoms and feet or meters and decimeters (tenths of a meter). Next determine the “Height Datum.”…

Here’s some great advice from Skipper Tips about how to use contour lines on land to help you navigate, either when coastal cruising or when making a landfall: Think of land elevation contours like those found in water–depth contours. Cartographers will sometimes indicate the height of a contour prominent enough to be sighted by a mariner. Heights will be shown as a number, so always check the chart datum to understand the height value. It could be in feet or meters. Make this your first step so that you know at-a-glance what the height values indicate. 1. Why Stagger Contour…