On 3/10/2010 10:39 PM, Doug Winterburn wrote:
Robert Bonomi wrote:
In ,
wrote:
Robatoy wrote:
On Mar 10, 4:01 pm, Pat wrote:
Which is how/why she could do 44kts(50mph), which is
pretty much hauling ass for anything that size in the
water.



Zz Yzx wrote:
http://www.popularmechanics.com/tech...on/4263478.htm...
Funny thing is, that she would probably do 42 kts with 50,000 HP and
the next 2 knots would take 3 times as much. Such is the rule of
displacement vessels. To take that one theoretical step further, if
they wanted to go 46 knots, they's need 400,000 HP. 47kt 1 million. 50
kts a bezllion HP
I think 55 knots or so is the theoretical maximum a vessel can move through
the water, irrespective of the power pushing it.

Nope. not even close

Currently, unlimited power-boat races are in the 160MPH range. in years past,
they got up into the 200 MPH range, but engine/fuel restrictions have brought
the speeds down.

'Cigarette' boats can reach 80+knots in calm water.

Some torpedoes -- which travel entirely underwater -- have sustained speeds
well over 100 knots.

unlimiteds aren't displacement boats, they're hydroplanes. Cigarette
boats are also on plane at speed and therefore not displacement vessels.
My physicist buddy that does torpedo testing says max speed for a
conventional torpedo is 55 knots, but supercavitating torpedoes are
capable of much higher speeds by essentially traveling in a gas bubble
and are therefore also not technically [water] displacement devices.

Your physicist buddy is playing word games. The torpedo is going so
fast that flow detaches from its surface at the transition from the nose
cone to the body. But it is most assuredly travelling in water.

In any case the British seem to be laboring under the misconception that
their Spearfish torpedo can exceed 60 knots. Perhaps he should call
them and inform them of their error.