How far is far?

Yesterday we covered 155 miles in 24 hours. The strong trade winds are pushing us along at a fast clip.

It might be worth mentioning what that distance means. There are a number of different ways that a distance like that can be measured. The boat’s speed and distance through the water are measured by a little paddle wheel that sticks down in the water. The GPS also totals the distance that it has moved. Both of these suffer from a similar problem. They don’t care if the boat is moving in a straight line, or in circles. They total the distance moved. Since the boat doesn’t travel in a perfectly straight line, both of these tend to overestimate the distance covered, at least a little.

When boat’s were guided across the ocean by sextant and stars, the “noon sight” taken when the sun was at it highest position in the sky for the day was usually the best fix taken during the day. So distance sailed was reported as the distance between the two noon fixes. This is basically what I do, although with GPS I can pick any 24 hour period.

I have a little spreadsheet that I use where I enter the longitude and latitude positions of two points and I get the distance between them. I double check with the dividers on the chart to make sure everything agrees.

Of course, I could run 100 miles in a day and get no closer to my actual destination if I wasn’t going in the right direction, but that is a whole other problem.

Today’s run is 146 miles, with 853 to go. Six or seven days left. We are both looking forward to life on a level floor where we don’t have to hold on every step!

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2 Responses to How far is far?

  1. Bill Kinney says:

    Hi Chuck,

    I work a hybrid of paper chart work and electronic navigation. I don’t maintain a DR plot, but rather plot a fix from the GPS to the paper chart every 24 hours while in the open ocean. As I get closer to land, I plot a GPS fix every 2 to 4 hours. Close in, I don’t work the paper chart so much, but I do look it over carefully for hazards that are harder to evaluate, or even to notice, on the chart plotter.

    When it comes time to follow the narrow channel into the marina that is new to me, the chart plotter is the tool of choice. But with the caveat that the skipper needs to keep his head outside the boat, and not treat the plotter like a video game.

    Bill

    Like

  2. Chucksters says:

    Good morning Sailors. Glad to hear all is well. I am scheduled to teach Nav. 2 this Sat. So I will reference todays post. Interesting with all the great electronics available today you still use a chart.
    Is your chart work basically DR and did you star by using a San Diego ref. point.
    Thanks Chuck

    Like

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