On 2008-11-18 19:14:32 -0500, Bruce in Bangkok
said:

but a boat doesn't necessarily float - see submarine, unterseabot, etc.

errrr ... they DO float, just not on top of the water most times.

--
Jere Lull
Xan-à-Deux -- Tanzer 28 #4 out of Tolchester, MD
Xan's pages: http://web.mac.com/jerelull/iWeb/Xan/
Our BVI trips & tips: http://homepage.mac.com/jerelull/BVI/

On Wed, 19 Nov 2008 01:23:41 GMT, Jere Lull wrote:

On 2008-11-18 19:14:32 -0500, Bruce in Bangkok
said:

but a boat doesn't necessarily float - see submarine, unterseabot, etc.

errrr ... they DO float, just not on top of the water most times.


I'm not a submariner but I believe that much of the time they are
heavier then water at the depth they are navigating and have a
positive angle on the planes to maintain depth.

Ping Larry for details.
Cheers,

Bruce
(bpaige125atgmaildotcom)

On Wed, 19 Nov 2008 08:31:29 +0700, Bruce in Bangkok
wrote:

On Wed, 19 Nov 2008 01:23:41 GMT, Jere Lull wrote:

On 2008-11-18 19:14:32 -0500, Bruce in Bangkok
said:

but a boat doesn't necessarily float - see submarine, unterseabot, etc.

errrr ... they DO float, just not on top of the water most times.


I'm not a submariner but I believe that much of the time they are
heavier then water at the depth they are navigating and have a
positive angle on the planes to maintain depth.

A modern military submarine tries to be as close to neutral buoyancy
as possible. But since exact neutral buoyancy is impossible, they
usually try to stay ever so slightly positive so that if something
happens and they lose control, they'll rise instead of sink.

Static uncontrolled rising and sinking is a positive feedback loop in
that as it sinks, the pressure goes up, the hull compresses and takes
up less water volume, becomes less buoyant, and the rate of sinking
becomes faster and faster. Not good. If it's initially positive
buoyant, as it rises, the rate of ascent becomes faster and faster.
Not nearly as bad as sinking faster and faster.

Steve