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Precision Rock Dumping


We have a great track record in the precision dumping of aggregates subsea onto and around subsea assets. We use bottom opening bulk bags with subsea deployment frames for stabilisation, scour-mitigation and free span correction.

In comparison to traditionally used techniques, our precision rock dumping solution reduces project cost by removing the need for a dedicated rock dump vessel. We lower aggregate to the seabed in either bottom-opening bulk-bags or large-capacity bulk-bags which can be tipped over underwater – allowing very precise and efficient placement of the aggregate.

Traditional spot rock dumping techniques using chuted bags, suspended on the crane hook result in a large spread of the aggregates. Similarly, dumping from a grab or excavator bucket presents the same issues and is limited to shallow water applications. In both cases, the large spread of the falling aggregates means significantly more materials must be transported offshore and installation times are correspondingly longer.

The highly accurate placement of our bottom opening bag system means less waste, less fuel burned and lower installation costs.

Our rock dumping solutions combined with concrete mattresses can provide robust stabilisation and protection measures that can withstand severe environmental conditions.


The bottom opening bag provides highly accurate deployement of rock at the target location, compared to a conventional bulk bag.

It is installed faster and lowers the risk of the operations as the ROV is not used to cut the bag.

Subcon provides an engineered custom built lift frame that deployed multiple bags in a single lift saving offshore installation time.

Subcon can provide a turnkey stabilisation solution for the client tailored specifically for the asset.

Alternatively, Subcon can provide bags and lift frame for deployment from client vessel.

Subcon has a standard size but can design and fabricate any bespoke solution.

Subcon owns the fabric manufacturing facility and therefore has complete control over quality and schedule requirements for bespoke solutions.

All Subcon bags are designed in accordance with DNV 2.71 and suitable for offshore lifting.


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Offshore Bottom Opening Bags GabionBag

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