ship stability (ergent)?

Question

do any body know any thing or help me to find some thing abouat bulk loading manual for ship

Answer 1

These two links should do.

The centerline is determined with the ship is at 0 degrees list. It is a verticle line that passes through the center of gravity(G). This line remains fixed with respect to the ships angle of roll. So a 10 degree roll this G centerline is 10 degrees from verticle. The centerof bouvancy also has a center line but this center line is always verticle no matter what roll angle.

The intersection of these two centerlines is wher the metacenter (M) is located.

Metacentric height GM (the distance between G & M)determines if a ship is stiff or soft (quickly rights itself or slowly) . GM combined with the righting arm (GZ ) create a torque which moves the ship in a righting direction for positive stability.

In a cross section of a ship the center of gravity(G)is a fixed point ( Not counting cargo shift etc) . While the center of bouyancy(B) location moves and is based upon the cross section of the submerged portion of the ship.

The easy way to visualize the torque produced by the righting arm GZ is to draw a down arrow from G and an up arrow at B. This will show the direction of the movement. The horizontal distance betwen G and B = GZ this is the lenght of the lever.

GM determines how long the GZ lever changes for a given roll angle.

The profile of the ship determines how much the B force changes for a given roll angle. Some ship profiles dramitacally increase there displacement as they roll, further increasing GZ. Ships with a top heavy load cause the G to rise closer to the metacenter (M) this has the effect of creating a smaller righting arm (GZ) and lowers the righting torque produced causing a longer period for the ship to right itself.