A load of estimated weight 3 tonne is to be lifted from a platform at a level of 20m above sea level. The vessel can manoeuvre so that the base of the centreline of the crane is within 20m of the lift. The sea state is calm
Lift Weight
The weight is a estimated 3tonne lift with a 100% factor of safety this gives a weight of 6 tonne for calculation. The 10 tonne block is fitted adding 0.2 tonne. The lifting accessories are estimated at 0.1 tonne. This gives a total weight to lift of 6.4 tonneLift Height
The height of the lift above sea level is 20m. The freeboard is 1.5m and the crane pivot is 4.1m above the deck This gives a lift height of 14.4mLift radius
The Lift is 20m from the centre line. The pivot is 2.1m behind the radius therefore the lift radius becomes 22.1mObstructions
The lift is clear of obstructions. However to clear the lift and ensure that the accessories are properly placed the Gib head has to be 2m above the lift. This changes the height of the boom to 16.4mCalculation of Boom extension
The easiest way to do the following is with graph paper with suitable scaling
however it is possible to calculate the required boom length.
