ROCKLAND — This presentation is a two-part series offered Sunday, March 6, at 3 p.m. and Sunday, March 20, at 1 p.m. This is an informational program given by Commodore Dutch Dresser on the diagram on the plane of the Celestial Meridian and Sextant observations and how they lead to lines of position.

The problem for those who navigate using celestial bodies is to create lines of position on a chart just as you would when taking a bearing on buoys or lighthouses. Creating these lines of position requires using two different sets of coordinates on the imaginary celestial sphere. While the celestial navigator uses either tables or a calculator to reduce the problem to mathematics, there is a beautiful diagram that shows the relationships between these two sets of coordinates and helps us understand celestial movements in a new way.

Participants will construct diagrams using the coordinates on the plane of the celestial meridian (local hour angle and declination) and on the plane of the celestial horizon (azimuth and altitude). This will create the navigational triangle that relates to the chart or plotting sheet in the second session of the program. By introducing some of the vocabulary and techniques, attendees will find the concepts and techniques more accessible than previously imagined.

Rockland Yacht Club invites all interested members of the community to attend this presentation and requests an RSVP to the Events Committee Chair, Dorrie Higbee, at dorrie@bluesprucejoinery.com. No prior navigation or boating experience is necessary.

Founded in 1927, RYC is a community yacht club supporting recreational boating activities in the Rockland area. For more information feel free to visit our website rocklandyachtclub.org.