So when you say "well within the bounds of most people to easily stay upright"
does that mean that out of 900 tourists given no warning, a number would land on
their butt?

How quickly does the thrust get reversed? 35 knots is 60 feet/second - if it
takes several seconds to do the reverse, that leaves well under a boatlength for
the serious deceleration.

This reminds me of another question I've had for a "pro." How quickly do you
figure a helmsman would react to a hazard in the water, especially given no
warning. For combat situations, I've heard it varies between a second or two
for the pro, to about 6 seconds for the civilian. From my own experience, I
feel like I respond pretty quickly if an event is something that I'm
anticipating, but the last I had a "close encounter" in the I was disappointed
that I felt like 2 or 3 seconds passed before I reacted. However, I was able
to do a crash stop before things got hairy, the T-boat that would have hit me
never flinched.

-jeff


"otnmbrd" wrote in message
...
I've been on a Fast Cat (@35k) during a crash stop, as a demonstration.
Stopping distance was within a boat length (this was one of the larger
cats) The maneuver doesn't involve changing engine speeds, just the
direction of the waterjet thrust, and was well within the bounds of most
people to easily stay upright (G though grabbing something was a good
idea).
I've also done this maneuver on Z-drive tugs .... same results ....
fact, we sometimes use this maneuver for pilot boarding. .... come down
the side of ship on opposite heading at about 5-6 k, crash stop and go
astern,in the opposite direction at 6-8k while coming alongside (ship
maintains 7-8 k).... (eg scares the bejeebers out of the first time
onlookers).

otn

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.