Does this ship steerable props (such as the Azi-Pod)? If so,
then there's no way the helmsman could make the ship roll no
matter how hard he turned.


Joe wrote:
What? I call BS.!

Are you telling me could not induce a roll on ship with pods?

I don't know if it's impossible to make the ship roll *any*
but it will certainly roll a heck of a lot less.


... Its a matter of sway, not propulsion.


No, it's a matter of forces around the centers of mass &
resistance. A rudder will make a ship roll because it is far
down below the waterline, and it only creates a force in one
direction. With an Azipod the ship is pulled (or pushed)
into a turn with much less heeling force generated. It's one
of the purposes of building it that way.

I suppose it follows that if the azipod (or any other
steerable prop) is used the exact opposite of how it should
be, the ship could roll even more... maybe that's what happened!

Anyway, google up the design brief on azipods if you think
I'm BSing.

Fresh Breezes- Doug King

DSK wrote:

Yeah sure agreed

Anyway, google up the design brief on azipods if you think
I'm BSing.


Sure the design is superior in moving any direction. The reason pods
are used on ships is to avoid harbor tugs and allow tight manuvering in
harbor, and they are a more fuel efficent diesel electric set-up. Has
nothing to do with stability of a cruise ship IMO.

Little experment, take a 4x8 sheet of plywood on edge, set course
straight down the street, then as you get up to speed push the aft
section left or right and see how the plywood sways. You turn something
that heavy fast it is going to sway, do a quick S you could induce a
very nice (even un-expected and deadly) roll with such a top heavy pig.

Joe


Fresh Breezes- Doug King

Anyway, google up the design brief on azipods if you think
I'm BSing.


Joe wrote:
Sure the design is superior in moving any direction. The reason pods
are used on ships is to avoid harbor tugs and allow tight manuvering in
harbor, and they are a more fuel efficent diesel electric set-up. Has
nothing to do with stability of a cruise ship IMO.


That's not the main purpose, agreed.
But it is a fact that an azipod will induce less rolling
moment on a ship because it can generate a force along any
vector, not just sideways very far below the ship's center
of mass like a rudder.


Little experment, take a 4x8 sheet of plywood on edge, set course
straight down the street, then as you get up to speed push the aft
section left or right and see how the plywood sways. You turn something
that heavy fast it is going to sway,

Wrong.

It sways because the force is not aligned on the horizontal
axis. In order to turn the object, the force must be either
forward or aft of the center of lateral resistance, and
since that's not necessarily the same place as the center of
mass.

In your example, will the plywood sway in the exact same
manner if the plywood is pushed from the bottom or from the
top? How about if it's pulled instead of pushed? How about
if the push (or pull) to turn it is aligned exactly along
the vertical center?

... do a quick S you could induce a
very nice (even un-expected and deadly) roll with such a top heavy pig.


I thought you and OTN were saying they're not that top
heavy? Anyway, a containership stacked as high as the bridge
will be very top heavy too.

DSK

DSK wrote:


I thought you and OTN were saying they're not that top
heavy? Anyway, a containership stacked as high as the bridge
will be very top heavy too.


Not me! Otn said that.

One look at that monster with all it's air borne swimming pools and
buffet carts one can assume she sways like a french girls ass if great
care in not taken to avoid it.

Joe

..
DSK

"otnmbrd" wrote in message
25.201...


Will be interesting to find out what happened. If someone
accidently hit
the wrong button during a course change it's one thing,
but if there is a
control glitch..... yikes.
Other possible contributor would be "stabilizers".
As for "top heavy".... she does look it, but the reality
is that she
probably isn't.

Car haulers look amazingly top heavy, like a gust of wind
would blow one right over.

Scotty

Scotty wrote:
Car haulers look amazingly top heavy, like a gust of wind
would blow one right over.


They look like nothing I've ever seen, certainly not like a
ship.

A lot of modern cruise ships look like some kind of
household appliance.

I wonder if the stability is a problem and we just don't
hear much about it? If a cruise liner capsizes, it will be
in the news though!

Fresh Breezes- Doug King

"DSK" wrote in message
...
Scotty wrote:
Car haulers look amazingly top heavy, like a gust of
wind
would blow one right over.


They look like nothing I've ever seen, certainly not like
a
ship.

I remember when I was a youngun seeing a shoe box floating
down a creek. Maybe the car hauler designer saw the same
thing?


--
Scotty
''One who never gets out of the Sound cannot, with any
degree of
credibility, comment on the courage of fellow sailors''
.....F.B.

"Joe" wrote in message
ups.com...

DSK wrote:
Scotty wrote:
Car haulers look amazingly top heavy, like a gust of
wind
would blow one right over.


They look like nothing I've ever seen, certainly not
like a
ship.

A lot of modern cruise ships look like some kind of
household appliance.


This ol thimer was quite amazing for her time. Still the
funkyest ever
IMO.
http://www.cynical-c.com/archives/bl...hics/flip2.jpg


Is that a channel marker?


--
Scotty
..''One who never gets out of the Sound cannot, with any
degree of
credibility, comment on the courage of fellow sailors''
.....F.B.

I heard the cruise ship had R&P steering.


--
Scotty
''One who never gets out of the Sound cannot, with any
degree of
credibility, comment on the courage of fellow sailors''
.....F.B.


"Joe" wrote in message
ups.com...
Now when on the helm of the fat sam I had a very hard time
inducing a
30 degree roll, lucky to get a 10 degree roll without
getting caught,
and we were 11 decks abouve the waterline.

I guess the fat sam was not as top heavy as the carnival
ship. I wonder
if the helmsmans was just FN with the passengers, or maybe
they engaged
the autopilot on the wrong course.

Critical injuries....oh my. That ship looks extreamly top
heavy, wonder
whats going to happen if it gets in a major storm, people
are going to
be slapped back and forth between the bulkheads.

Joe

Scotty wrote:
"Joe" wrote in message
ups.com...

DSK wrote:
Scotty wrote:
Car haulers look amazingly top heavy, like a gust of
wind
would blow one right over.


They look like nothing I've ever seen, certainly not
like a
ship.

A lot of modern cruise ships look like some kind of
household appliance.


This ol thimer was quite amazing for her time. Still the
funkyest ever
IMO.
http://www.cynical-c.com/archives/bl...hics/flip2.jpg


Is that a channel marker?


No it did research on ocean tides. The other half of the ship is under
water. It would travel like a regular ship, then flood to act as a bouy
or platform and plot tides. Cold war tech at it's best.

Joe



--
Scotty
.''One who never gets out of the Sound cannot, with any
degree of
credibility, comment on the courage of fellow sailors''
....F.B.