Compensated feeder operations

 

Workability increase for Feeder barge operations

The Seaqualize Delta enables safe and continuous heavy lifting from feeder barges, supplying offshore installation jack-ups.

Delta 600 Feeder barge operation

 

Key benefits

Using inline AHC tooling offers significant advantages over the use of standard passive heave compensators:

Delta Functionality Advantages for Feeder Lifting
Easy adjustable tension
    - No switching between weak / stiff mode:  Easiest engineering, just choose what tension you need, at each part of the operation
    - Lift varying weights:  No need to reset for varying weights, keep on lifting in 1 go
Constant tension over full stroke
    - DAF < 1.1: No sudden or unknown load increases
    - Safe release: Tool ensures ~90% pre-load into rigging.
    This allows more time to release fastening without risk of load falling over (e.g. high towers or direct drive nacelles)
Automated lift, with high speed
    - No risk of re-hit: always lift automatically at top of a
    wave, with at least 0,5 m/s 
Mechanically actuated lift
    - Quick lift is reversible: differing from simply opening
    gasvalve on PHC for quick lifting
Hook Based, not on each Barge
    - You only need one:  compared to 2 or 3 tools when using barge based solutions
Low power requirement (~30kW)
    - Battery powered:  No umbilical needed when continuously operating ~3 to 4 hrs
    - Continous lifting:   No recharge needed, you can empty the deck in 1 go
 

~80% and higher workability in winter months

Potential workability improvement (in %’s, based on heave limits) by using the Seaqualize Delta inline AHC, for US feeder barge operations at the site of the Vineyard Offshore Wind Farm, 180 degree incoming sea and swell waves, with a lifting location at the far stern of the deck

No need to stop in the winter season: we can offer >80% workability almost all year round.

We’re more than happy to customize our workability analyses based on your project details, such as:

  • Project location

  • Vessel details (RAOs) or motion time traces

  • Deck loading configuration

 
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Delta2 Hexapod Feeder Barge test.JPG
 
 

Operational steps

Advanced simulation allows us to test the Delta in every situation. Below is an example of the craneload during a feeder barge lifting operation conducted in a simulation with a HS of 2.5m

During this lift, the load is gradually shifted from the barge deck (0%), to the crane (100%)

Below, we will detail out the key operational steps

 
 
 
 
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Hook-in: follow barge motions

In heavy seas connecting the rigging safely
is a difficult task. With the Delta, you can actively follow the heave motions of the barge:

  • Follow mode

    • Connection hangs still relative to heaving load

    • Reduces danger for rigging crew

    • No heavy impacts of rigging with the load

 
 
 
 
 
 
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Pretension to check rigging

To check correct rigging alignment, the tool operator can slightly pretension the rigging:

  • Fully controllable / adjustable pretension level (e.g. 10%)

  • Tension fully constant over stroke: no snatch loads or premature lifts when nearing end-stops

  • Reversible and adjustable at any moment

If the lifting supervisor gives the green light, the tension can be increased in any rate

 
 
 
 
 
 
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Controlled load build-up: no premature liftoff

Once the rigging is checked, the load can be built up as fast or slow as needed. The Delta can ramp up the load from 10% to 90% in a pre-agreed manner:

  • Quick enough to keep full procedure as fast as possible

  • Controlled enough to ensure

    • No pre-mature lift-off, contact is assured

    • DAF <1.1

    • Time for ballasting crane vessel if needed

The load build up into the crane is gradual and fully adjustable

 
 
 
 
 
 
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Controlled release

The Delta ensures a constant (and adjustable) constant tension on the load. This makes releasing sea fastening much safer and more controlled, as it limits lifting hazards:

  • Tower sections toppling over due to roll-pitch angles of the barge

  • Nacelles with COG outside of the flange area (DirectDrive components) falling from their sea fastening frames once released

Together with our partners, Seaqualize can provide sea fastening for tower sections with a passive roll compensation system. When combined with a 90% pre-loading into the crane rigging, this ensures a safe and controlled tower lift off.

The Delta can ensure a constant (and adjustable) constant tension of e.g. 90% making the moment of releasing the sea fastening much safer and more controlled

 
 
 
 
 
 
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Automated Quick lift

When ready for lifting, the Delta can automatically time the quick lift at the top of a wave. This prevents any re-hits with the barge deck

  • Automatically lift at the top of a wave: The operator can give the green light, after which the tool automatically quick-lifts at the next wave peak. Of course a fully manual lift-off is still possible if so desired

  • Quick lifting speed: 50 cm/s + normal hoisting speed

  • DAF still remains < 1.1, as the quick lift is done while 90% of the load is already lifted

 
 
 
 
 
 
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 Continuous operations

The Delta can keep lifting, no need to go back to deck, even when lifting varying loads.

  • Complete flexibility to choose lifting order: from heavy to light or vice versa

  • No need to recharge, full barge can be emptied on 1 battery charge

 
 
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Place back on barge

To free up deck space, the Delta can transfer any unnecessary tools or materials back to the feeder barge.

  • The Delta can securely transfer all light and heavy objects

  • The Delta assures a soft touch-down, using its follow-mode to actively match the speed of the heaving supply vessel or barge

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Delta2 Hexapod Feeder Barge test.JPG
 

Prototype testing

In this test, we used our Delta2 prototype to demonstrate a controlled and compensated feeder barge lift.

The Delta2 picks up, safely, controlled and automatically, a 400kg load from a heaving deck (simulated by an Ampelmann hexapod). No snatch loads, accidental lift offs and re-hits. And importantly: No need to wait for recharges before you can lift the next component: You keep on lifting as long as needed, even for varying weights!

 
 

Delta2 feeder barge testing together with an Ampelmann motion compensating platform

 
 
 

Partners: the Feeder Barge Alliance

Seaqualize teams with several partners that offer complementary products and services for feeder barge operations. Jointly we simulate complete operations, estimate full workability improvements, and coordinate efforts to remove operational obstacles for clients

 
 
 
Logo Sea of Gravity

Sea of Gravity Offshore

is a field tested integrated service provider to the offshore energy industry, with extensive WTG transport experience, including turnkey receiving, marshalling, and offshore delivery of WTGs and Foundations.

www.seaofgravity.com

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Eager.one

is a company that designs and supplies bespoke project equipment for lifting, handling, sea fastening and access. For feeder barge operations, they have designed and built remote controlled lifting tools and sea fastening, focusing on reducing crew required on board of the barges

www.eager.one

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Next Ocean

is a company that enables to reduce risks and increase workability offshore by providing detailed insights in the local wave conditions. Using Next Ocean’s WavePredictor it is possible to forecast motions of a vessel for different headings. And by using radar to scan each and every individual wave in the vicinity of the vessel, Next Ocean’s WavePredictor provides insight in upcoming quiescent periods to safely execute critical steps in the operations.

www.nextocean.nl

Read our joint white paper, including a detailed workability analysis based on the Vineyard Windfarm lease area, the results may surprise you!