Ships in Parametric Roll For ships we describe the 3 transla

Ships in Parametric Roll. For ships, we describe the 3 translations and 3 rotations as seen in the following sketch. Roll is defined as rotation about the x-axis where the positive x-axis is defined in the direction of motion of the ship.

Solution

Although the question is not very clear. I mean, it is not given, what you are asking.

If you are asking about what is parametric rolling. The answer goes as below:

The new container ships coming to the market have large bow flare and wide beam to decrease the frictional resistance which is generated when the ship fore end passes through the water, making it streamlined with the hull.

As the wave crest travels along the hull, it results in flare immersion in the wave crest and the bow comes down. The stability (GM: Distance between metacentre and centre of gravity) varies as a result of pitching and rolling of the ship. The combination of buoyancy and wave excitation forces push the ship to the other side.

The similar action takes place as the bow goes down in the next wave cycle resulting in synchronous motion which leads to heavy rolling up to 30 degrees in a few cycles. This type of rolling is known as Parametric rolling.

In general parametric rolling occurs only under the following critical conditions:

Effects of Parametric Roll