Bundles and towed installation

Bundles and towed installation

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CONTROLLED-DEPTH TOW – TOW-OUT FORCES

‘Lift’

Drag

Tow speed

Weight

Weight

At trimming station

During towout

At field

Flooded for stability

All the chain weight acts vertically at the trimming station. As the tow gets underway, the chains adopt an inclined angle as they suffer from drag through the water. The associated hydrodynamic lift on the ballast chains reduces the net weight, causing bundle to rise in the water column. Initially, the front towhead lifts off and gradually, more and more of the bundle ‘unglues’ itself from the seabed. Eventually, the trailhead also lifts off and the whole bundle ‘flies’ through the middle of the water column. It returns to the seabed once towing stops at the field. At this stage, the nitrogen is replaced by flooding with treated seawater.

ORCAFLEXANIMATION CONTROLLEDDEPTHTOW

ORCAFLEX ANIMATION – CONTROLLED DEPTH TOW