Dynamic Loading

The Effects of Dynamic Loading on the Lifting Capability of a Crane

For this document 'Dynamic loading refers only to the effects of movement of the vessel due to rolling only. The effects of Pitching, lift and lower acceleration and deceleration, relative movement between vessel and platform from which weight is being lifted or lowered to is not considered.

Effects of Heel Angle

As the crane comes under load there is a tendency for the vessel to heel towards the load. The effect of this is to increase the lift radius. This effects increases with increasing boom length.

Increase in Lift Radius = New Lift Radius R2 - Original Lift Radius R1

= LCos Ø₂ - LCosØ₁

= L ( Cos Ø₂ - Cos Ø₁ )

It can be seen that this effect increases with increasing boom angle.
For example with an original boom angle of 20^o a heel of 5^o will increase lift radius by about 3%
At 65^o the same heel will increase lift radius by about 8%

Lift radius is computed as a function of Boom angle and Boom Extension only; no compensation is given for Heel. In such conditions Overload may occur and proper planning including a reduction in the Lift capacity should be made.