Frankly, don't know - this is way outside my experience. However, I'm a bit
impressed that a large ship can stop from 10 knots in little over a boat length.
Is this typical for traditional displacement ferries?


"MC" wrote in message
...
I've not seen a system that adjusts for full thrust in reverse or ahead.
But, the 10s crash stop is hardly impressive. Imagine taking 10s to slow
from a gentle run to a stop! Then again, the big water jet cats I've
ridden on here seem to have little power astern. I've also noted that
they power up ahead quite gently and if the throttle is opened
agressively the pump seems to make caviation type noises. It might be
that the water jet intake is optimised for power ahead?

Cheers MC

Jeff Morris wrote:

I don't know ... do water jet propulsors cavitate in full reverse?

Or is it possible that this system adjusts the throttle automatically for
maximum thrust?


"MC" wrote in message
...

Good lord. Do they really think that full astern the best way to slow a
fast vessel? Do you think they felt the extreme cavitation?

Cheers MC

Jeff Morris wrote:


This is for a vessel 91 meters long, d5617 tons, carrying 900 passenges and

240

cars.

From the accident report:
"After the collision, a speed trial was performed on board the "INCAT 046"

with

three engines in service, as they were the night of the collision, to

determine

the crash stop distance of the vessel. This was done by taking her to a

preset

speed and then setting the engine control to 100 per cent power astern. At
a
speed of 10 knots the ferry was able to come to a complete stop within 111

m, in

about 30 seconds. The speed was then increased to 14 knots and the test
performed again. The ferry was able to stop within 163 m, in about 45

seconds."

From a Navy evaluation:
"In addition, it demonstrated the capability of performing a "crashback"

(i.e.,

coming to a dead stop) from 46 knots in just a third of a mile. This is

amazing

for a vessel of this size, especially compared to a modern aircraft carrier

that

requires approximately 2 miles to stop."
http://www.tea.army.mil/pubs/nr/depl...HSSarticle.pdf

I admit this isn't pulling that many G's, but out of 900 people, many of

which

could be walking around, I'm sure they would end up with more than one

lawsuit.

BTW, this was originally built for the Bass Strait run.


"MC" wrote in message
...


Do you really mean 10 knots to full stop in 110 meters? If so, that's a
fairly gentle stop from a slow 'fast cat'.

Cheers MC

Jeff Morris wrote:



"robert childers" wrote in message
om...
IMHO a kayak would not be an impediment to a large vessel in any of
the cases you are citing. They'd scarcely know there were bits of
fiberglass in their wake.

You're quite correct - but what if the vessel is a high speed ferry and
it

does


an emergency stop? The Bar Harbor Fast Cat can go from 10 knots to full

stop in


110 meters, but what happens to the 900 people on board?