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Geodesic versus great circle
From: Bill Lionheart
Date: 2018 Nov 16, 17:07 +0000

Not exactly celnav but closely related When ships are routing they must be trying to minimize energy used (or a trade off between that and passage time). Obviously optimal routing would use prediction of wind, tide and maybe wave height. But as the earth is not a sphere the geodesic (shortest distance path) is is not a great circle. Is the difference between geodesic and great circle (around one percent at most I think) insignificant compared to the variation in the other factors, or could ships save a worthwhile amount energy if they plan using the geodesic route. Given the huge energy consumption of ships maybe 1% is worth it? Maybe they already do it, as presumably big ships just use software to do routing. Bill Lionheart

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