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