Collection of recommendations and tips

# What is area under GZ curve?

## What is area under GZ curve?

1. The area under the righting lever curve (GZ curve) should not be less than 0.055 metre-radians up to 30° angle of heel. 2. The area under the righting lever curve (GZ curve) should not be less than 0.09 metreradians up to 40° angle of heel or the angle of downflooding if this is less than 40°.

## What is the purpose of angle of loll?

The angle of Loll is that angle of heel at which a ship with negative GM will come to rest. It is an extremely dangerous situation and in extreme cases, a vessel may even capsize. A vessel with Negative Initial GM will tend to capsize.

How do you find the initial GM of a GZ curve?

INITIAL GM: CAN BE FOUND BY DRAWING A TANGENT TO THE CURVE THROUGH THE ORIGIN AND THEN ERECTING A PERPENDICULAR THROUGH THE ANGLE OF HEEL OF 57.3 DEGREE. THE 2 LINES ARE ALLOWED TO INTERSECT AND THE VALUE OF GZ IS NOTED WHICH IS THE INITIAL GM.

What is the minimum stability requirements and recommendations of the Intact Stability Code?

A ship is seaworthy if it fulfills two important stability criteria- Intact and Damage stability. Initial GM or metacentric height should not be less then 0.15 m. Righting lever GZ should be at least 0.2 m and angle of heel Ѳ ≥ 30̊. Maximum righting lever should occur at heel >30̊ preferably but not less than 25̊.

### How do you read a GZ curve?

Calculating the value of GZ, at specified angles of heel for a ship’s particular condition of loading, will allow a curve of statical stability, or GZ curve, to be produced. The greater the values of GZ, the greater will be the area under the curve.

### What is GZ in stability?

GZ is known as the righting arm. The plot of the righting arm GZ calculated as the function of the heel angle, at constant displacement and vertical centre of gravity KG values, is used to measure the ship stability at large angles of heels. It is called the curve of statical stability.

What is a GZ curve?

The curve of statical stability, or GZ curve as it is most commonly referred to, is a graphical representation of the ship’s transverse statical stability.

What is the difference between angle of loll and angle of heel?

Angle of loll is the state of a ship that is unstable when upright (i.e. has a negative metacentric height) and therefore takes on an angle of heel to either port or starboard. When this occurs, the vessel goes to neutral equilibrium, and the angle of heel at which it happens is called angle of loll.

## What is GZ in ship stability?

The vessel’s centre of gravity (G) has a distinct effect on the righting lever (GZ) and consequently the ability of a vessel to return to the upright position. The lower the centre of gravity (G), the bigger is the righting lever (GZ).

Why margin line is 76 mm below deck?

A line drawn at least 76mm below the upper surface of the bulkhead deck at side, (SOLAS). The margin line is a line defining the highest permissible location on the side of the vessel of any damage waterplane in the final condition of sinkage, trim and heel.

What is the use of GZ curve?

The dynamic stability may be determined by measuring the area under the righting lever curve (GZ curve) up to a certain angle of heel. The larger the area, the better is the dynamic stability. Waves are the most common external force that causes a vessel to heel.