Stability

Question 1

WL

Answer 1

Waterline

Question 2

CL

Answer 2

Centreline

Question 3

K

Answer 3

Keel

Question 4

B

Answer 4

Centre of Buoyancy: the centroid of the underwater volume of the ship. It is the point through which the force of buoyancy is considered to act vertically upwards.

Question 5

G

Answer 5

Centre of Gravity: the center of mass of the ship. It is the point through which the force of gravity is considered to act vertically downwards.

Question 6

M

Answer 6

Metacentre: the point where the vertical line up through the Centre of Buoyancy intersects the Centreline. It is constant for small angles of inclination (up to about 10º)

Question 7

KG

Answer 7

Height of the ship’s Center of Gravity above the Keel

Question 8

KM

Answer 8

Height of Metacentre above the Keel

Question 9

GM

Answer 9

Metacentric Height: this measurement is calculated by subtracting KG from KM (GM = KM - KG). GM is a measure of the ship’s initial stability.

Question 10

BM

Answer 10

Metacentric Radius: the distance between the Center of Buoyancy and the Metacenter. It is actually the radius of the circle for the movements of “B” at small angles of inclination.

Question 11

Positive Stability

Answer 11

G is below M

Question 12

Neutral Stability

Answer 12

G is coincident with M

Question 13

Negative Stability

Answer 13

G is above M

Question 14

Trim

Answer 14

may be considered as the longitudinal equivalent of list, which is the transverse inclination of the ship due to movement of the ship’s center of gravity.

Question 15

F

Answer 15

Center of Flotation (F) is the geometric centre of the waterplane area.