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Small is beautiful: a new take on transfers

A compact transfer device with a minimal footprint has been developed by Baltec Offshore that might help CTVs move beyond ‘bump and jump’ manoeuvres – while keeping their speed.

The issue, Odo Huetter of Baltec told MJ, is that traditionally transfer operations depend on pressing the vessel’s bow against the boat landing. But relying on the ‘push and stick’ approach can nevertheless lead to sudden movements as bigger waves suddenly overwhelm the friction: “This can be very dangerous - there have been accidents with technicians ending up in the water.”

While there are the big, complex Amplemann-type solutions, these are weighty, 30 tonne or 40 tonne beasts needing a large vessel to support them. More, they are demanding when it comes to deck space and time, both factors limiting their use to sizeable Walk-to-Work vessels.

However, Baltec has designed an alternative suitable for much smaller CTVs. The Rolling Jack is a fast, compact active heave compensated platform with a capability of 400kg of lift – plenty for three technicians and their kit. The machine itself is an incredibly lightweight 1.4 tonnes due to composite technology adapted from the aerospace industry; more, it has a very small footprint of just under 2.0m2.

The way it has achieved this is by separating out some of the motion mitigation issues from each other. Mr Huetter explained that at the foot of the unit on the bow (or stern) is a big roller instead of a rubber fender: when the vessel pushes onto the landing this roller allows the boat to slide up and down easily “so there’s no sudden jerk from the slip-stick effect”.

To counteract this up and down movement, the Rolling Jack has a mast of steel and carbon fibre with a moving platform. This provides vertical compensation via an electrically propelled, rotary ‘screw’ thread: “It’s not hydraulic as that tends to be really very bulky and heavy,” he pointed out. Information from sensors, accelerometers and motion reference units is fed through to the lift components, allowing the platform to cover a range of 4m, or roughly 2m significant wave height, a margin well beyond the normal transfer window.

Down below, the base focuses on keeping the tower upright against the vessel’s roll and pitching movements. It has three, stainless steel electric servo-actuators which lend the unit an ability to deal with roll angles of +-20° and pitching compensation of +-15°.

Working together, these systems hold the platform still against the tower to within 10cm.

The Rolling Jack promises to be a whole lot simpler, faster and less pricey than the bigger, traditional systems. There’s minimal waiting time, the kit gets to work almost on contact, and as the vessel is pushed on to the tower the motion compensation doesn’t have to extend itself to covering lateral motion.

Lastly, costs have been kept down (and dependability kept up) by a careful selection of parts: Mr Huetter explained that the ability to use very reliable, pre-tested ‘off-the-shelf’, components is a central part of Baltec’s strategy.

Small is beautiful: a new take on transfers

Details

  • United States
  • Stevie Knight