[kenbolton]

I know the estuarine river very well in my part of the world and the approximate distances between various landmarks and aids to navigation. Places I don't know as well, I use nearby features: cars, houses, aids to navigation, etc., to approximate. Exact accuracy isn't critical as normal cruising speed is around four knots. I know the distance from the George Washington Bridge to the Statue of Liberty is about 12 miles, and about ten miles from the GWB to the Battery. It is about six miles from World's End to Anthony's Nose and the Bear Mountain Bridge. It is about 1.5 miles from Little Stony Point to Pollepel Island and another 1.5 to Denning Point.

I also know about how large the various adult birds appear at various distances, recognizing that there is some variability. If it really mattered, I could carry a range finder.

Navigating in the open ocean, with no landmarks, is a little different. I have two compasses: one on my deck and one in my life jacket with my marine radio. I keep a charged phone with GPS and local marine charts in a dry box in a dry bag in a dry hatch in my boat, but have yet to rely on it. I look up the velocity and direction of the predicted currents and keep a chart of that on the deck along with my navigational chart. I plot my course on the chart and note the headings to my next waypoint. I keep a duplicate of the predicted currents and headings in a waterproof notebook on my body in case the chart gets separated from my boat. I note my departure time and calculate my velocity based on my normal cruising speed, adjust that for conditions – wind, current, company – and go for it.

I practice this on my local waters because I've been enveloped by fog off the coast of Maine. In September 2019 at low tide in the morning, three of us in a line with about twelve inches between stern and bow, we were unable to see the other paddlers in their cockpits, which means visibility was no more than seventeen feet. We navigated by instruments, ocean swell, and wind direction for two hours before the fog burned off.