Sextant makes an excellent racing tool

A stroll down Brown’s Wharf in Baltimore on the morning of October 13, 1994 would have seemed like a walk through another century as 24 schooners made preparations for the start of the Fifth Annual Great Chesapeake Bay Schooner Race.

We got the training schooner Ocean Star underway in a light and variable wind; it appeared that we might be ghosting down the 120-mile-long courseless than desirable conditions for these traditionally-rigged boats. Luckily, the breeze filled in from ENE, and 24 schooners began reaching down the bay in what would prove to be the fastest Schooner Race thus far.

As we moved away from the start, the fleet began to settle down somewhat, and we were able to take stock of our position and performance in relation to the rest of the flotilla. For those boats abeam of us, a simple compass bearing, taken at regular intervals, served to tell us whether we were gaining or losing ground. However, for boats ahead and astern, the problem was more complex. Compass bearings were inconclusive as we were all traveling in the same direction. Radar, as well as being a drain on battery power, was laborious to use, as the fleet was tightly clustered, making it difficult to distinguish targets as they shifted position.

However, as navigation training is the primary mission of Ocean Star, we had one more device available in our arsenal: the sextant. Focusing one of our ship’s sextants on a vessel ahead of us, I split the image until the highest point of their mast was just touching their waterline. The angle and time were recorded, and six minutes later the process repeated.

The principle at work here is the time-honored method of determining distance off of an object by vertical sextant angle. For the purpose of the race, all that was required was to recognize the height of the ship as a constant, so that any change in the measured angle must be attributed to a change of distance: the larger the angle, the closer the object. We ignored the standard distance off calculations and used a simple comparison of Hs 1 and Hs 2. The comparison showed that we were gaining on the other boat since the measured angle grew over the six-minute period. This was confirmed by a third sight, and finally proven as we overtook the other boat within the next hour. By this method, we could easily track several vessels at once without having to decipher one target from another on the radar screen.

Richard Jacoby often sails as first mate aboard Ocean Navigator’s training schooner Ocean Star

By Ocean Navigator