CRANE ENHANCEMENT
Previous
page
It is a well known fact that offshore cranes are subject to dynamic forces
while lifting cargo off a moving vessel. Also, the crane has to accelerate
the cargo away from the vessel to prevent collision when the vessel rises on the
next wave. In order not to overstress the crane, the lifting capacity must
therefore be
de-rated by varying wave heights and vessel types.
The problems mentioned above are taken care of by the crane enhancing
gear. This gear consists of two systems :
- The HICO system, which will almost remove the dynamic load imposed on the
crane by the wave actions.
- The SEACO system, which will remove the need for lift-off by the crane in
order to avoid contact between vessel and cargo.
The operation is therefore considered as a static load transfer, during which
no lifting takes place. Later, when the cargo has been transferred from the
vessel to the crane, the lifting by using the crane may start.
This patented PEF lifting
principle, called the HICO system, has been designed to perform the following
operations:
- Pre-stress the crane before load transfer in order to take up most of the
slack and elasticity in the wires and crane rig.
- Perform a controlled load transfer when the cargo is on the top of the
wave, and therefore without dynamic energy.
- Protect the crane against overload, by not accepting higher loads than the
crane maximum static load capacity. (The unit will simply pay-out, and the
cargo will not leave the vessel.)
This unit, called the SEACO rig, may be designed in many different ways and with
various capacities. The unit on the picture has a lifting capacity of 800 ton,
and is not made for use with the platform cranes. The SEACO rig has been
designed to perform the following operations:
- To transport the cargo safely on the vessel
- To lift the cargo up before load transfer
- To retract instantly by removal of the cargo
- To perform so called soft transfer operations if the sea is too calm for
pick-up.
The HICO machine used with a simple SEACO aft on the vessel may do the trick is
you have to lift loads above the de-rated capacity of the platform crane.
Using a SEACO system integrated into the vessel deck, the cargo may be carried
on deck level, and several objects may be transferred to the SEACO at the
platform before pick-up with the HICO system and the platform crane.
Advantges :
 | The HICO system literally removes the dynamic forces acting on the crane
during load transfer |
| The HICO system protects the crane against overload |
| The SEACO system makes it possible to transfer the load from the vessel at
no lifting speed. |
| The SEACO system protects the cargo from damages due to collision with
vessel etc. |
| Waiting on weather is reduced |
| Crane maintenance is reduced |
| Crane life time expectancy is increased |
| Reduced cost and time for crane operations |
TR Consulting 
