A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: Frank Reed
Date: 2019 Nov 5, 11:46 -0800
"he said that if a marine sextant was being used the boat had to fly at 20 feet."
That's interesting. The sea horizon is not normally visible above a few thousand feet. It makes sense to fly at perhaps 250 feet if the navigator is using a marine sextant. The sea horizon is visible, and the sensitivity of the dip to exact altitude is reduced. But why 20 feet? Is it possible that flying at very low altitude was more stable due to ground effect? Or was it merely a random recommended practice?