NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Propulsion power: was [Nav-L] Barrels
From: Trevor Kenchington
Date: 2005 Jan 19, 21:38 -0400
From: Trevor Kenchington
Date: 2005 Jan 19, 21:38 -0400
Bill asked:
> 1. Do you know the formula/ratio involving LAW, speed and depth when this
> limiting factor/resistance comes into play?
I can't find it. (Hope someone else can!) But it does act at a
surprisingly great depth: A 600 ft ship running at 25 knots experiences
some extra drag from the seabed at 25 fathoms depth, for example. It is
a problem for designers of measured miles, who need to find sufficient
depth close enough to land.
> 2. Would a submarine making speed very close to the bottom be slowed down,
> and or forced upward (perhaps bow up, stern down) because of the above
> dynamic?
Yes -- except that a submarine running fast, close to the bottom is all
too likely to be slowed even further by hitting something solid.
Something similar can slow ships in deep water if there is a shallow
thermocline, though the mechanism of energy loss is rather different and
so are the ways of escaping the extra drag.
Trevor Kenchington
--
Trevor J. Kenchington PhD Gadus@iStar.ca
Gadus Associates, Office(902) 889-9250
R.R.#1, Musquodoboit Harbour, Fax (902) 889-9251
Nova Scotia B0J 2L0, CANADA Home (902) 889-3555
Science Serving the Fisheries
http://home.istar.ca/~gadus
