NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: awareness
From: Herbert Prinz
Date: 2003 Apr 23, 22:42 +0000
From: Herbert Prinz
Date: 2003 Apr 23, 22:42 +0000
Jared Sherman wrote: > <"If the pitch of the prop is 26.3 ft. and the revolutions of the shaft is 87,421 > revs. in a 24 hr. period,calculate the days advance allowing for a negative > 7 % prop slip."> > Does that resolve to 26.3 ft. x 87,421 revs.= > 2,299,172.3 feet per day less 7% slip= > 2,138,230.2 feet per day advance? Yes, this is exactly what it resolves to. > And does anyone actually count shaft rotations as a means of dead reckoning? Doesn't everybody? > And, how are you supplied with slip for a particular prop and hull? Or is that something you have to measure and calculate while under way? Jared, have you ever wondered what all these Measured Mile Markers are for? And engine revolution counters and tachometers? A patent log, by the way, is just the inversion of the same principle. It, too, suffers from slip and has to be calibrated regularly. Herbert Prinz
