Deck Crane Lifting Operations

The following contains subjective comment on lifting operations with the Grove AT1500, telescoping crane with flyboom It does not constitute a set of instructions and does not supersede in any way LOLER of other lifting operation regulations. In addition there are several factors such as outrigger extension, outrigger pad size and ground state which have been specifically excluded as they apply only to a shore based lift. We assume that the counterbalance weight is fixed and that the stability area of the load capability chart does not apply
In addition not considered here is the trim of the vessel although this will have an effect and should be considered

Crane Mounted Load Computer

The Grove Crane has a load computer which measures the load weight, Boom Extension and Boom angle. Form this it can compare computed load against a model stored within its memory. As the load approaches overload alarms are sounded. The computer has an extra mode which takes into account operation with the flyboom. This load computer is there as a safety factor and in no way should be considered to replace proper planning.

Lifting operations.

To carry out a safe lifting operation a set of variables must be known; these consist of the following
• The weight of the lift.
• The height of the lift
• The Radius of the lift
• Obstructions within the lift area
• The Sea State

Weight Of lift

This may be either a known weight i.e. a weight which is certified and clearly marked, or an unknown estimated weight- in which case the weight is estimated and a factor of safety applied

To be added to the lift weight is the weight of the hook and lifting accessories before calculations are carried out. For the hook this is given as a test weight of
• 0.20 tonne for 10t hook and headache ball
• 0.65 tonne for 50t 3 sheave block

Note that unless the lift weight is certified it is always classed as estimated in all circumstances.

Height of the Lift.

Note this is measured form the boom pivot point and not the deck. The height of the pivot point above the deck is 4.2m

Radius of Lift

In a similar fashion the radius is measured from the pivot point and not the centreline of the crane. The distance from the pivot to the centreline is 2.1m

Obstructions within lift area

The area not only where the load will be lifted and put down, but also the area covered whilst the crane is slewing. Should this be of particular concern a lifting plan should be created and discussed with the crane driver highlighting areas of concern and how best the Crane drive may avoid them. It should be understood that the crane driver may be unsighted of some of these obstructions therefore where this is considered to be a high risk a lift supervisor should be designated to guide the crane driver at all times. Special consideration has to be given to lifts of unusual shape or where spreader bars are in use.

The Sea State

Vessel lift operations differ from shore based operations in that dynamic load forces have to be taken into consideration. The worst sea state condition considered to occur during the whole operation should be used and lift calculations based on that The Dynamic Loading factor stated in QGPS Lifting Equipment Regulations is 2.4 times for routine loading/unloading. A factor of 1.35 may be applied after written consent. maximum wind speed is given as 25knots and maximum wave height of 2m

Lifting tackle Inspections

A lifting tackle inspection by a competent person is required on all lifting accessories every 6 months. However, it is also required that all lifting accessories are examined for defects before use and this includes all crane operations. Appendix C gives a listing of the failure parameters applicable to typical lifting accessories