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A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Barrels was DR thread from Nov-Dec '04
From: Bill B
Date: 2005 Feb 1, 17:54 -0500
From: Bill B
Date: 2005 Feb 1, 17:54 -0500
Doug Wow! Regarding: w = pld displacement W = new displacement Can you further expound on the meaning of the above? Thanks Bill > Doug > > George posted a plausible explanation of the cube method, but I have not > seen your posting on how a merchant marine would solve the problem. > > Any hope I will see another way to skin the cat from you? > > Bill > > > > Here you go: > > s = old speed > S = new speed > c = old consumption > C = new consuption > w = pld displacement > W = new displacement > r = rpm at s > R = rpm at S > Ve = calculated speed by rpm > Vo = observed speed > De = calculated distance by rpm > Do = observed distance > > Slip > - slip = vessel speed outruns screw speed > + slip = screw speed outruns vessel speed > > by speed > % slip = ((Ve - Vo)/Ve) x 100 > by distance > % slip = ((Do - De)/De) x 100 > > Fuel Consumption > > by displacement > log C = (log c + 2/3 log W)- 2/3 log c > by speed > C =(c x S cubed)/s cubed > > Speed by RPM > speed in Kts = (60 x rpm x pitch x (1 - % slip))/6080 > rpm at given speed > rpm = 6080/((pitch/1 + % slip) x 60) x speed in Kts > rpm needed for new speed > rpm = (r x S)/s