New multifunctional concept provides flexibility in heavy transport and offshore installation
Reduced fuel cost - Green Passport - Zero Dumping

Damen Shipyards presents a new shipping concept to the market - the Damen Offshore Carrier (DOC) 7500 - specifically designed as a smaller heavy transport, offshore installation and ro-ro platform suitable for multiple markets. The Damen Offshore Carrier aims to provide flexibility and year-round utilisation.

Damen developed the new vessel in cooperation with Singapore based heavy lift transport specialist Hans van Mameren, managing director of Ha-Ce Engineering Pte Ltd.. The DOC has an endurance of 65 days, a large, flat and unobstructed deck of 2,300 m², a deck strength of 20 t/m² and is highly fuel-efficient.

Remko Bouma, Sales Manager of Damen Shipyards Bergum, says: "When we decided to realise a new design together, we wanted to create a vessel that was able to carry modules and cargo on an open deck over medium and long distances, complying the demands of today's market. I think this vessel will be 'the' alternative for the more time consuming tug and barge transportations."

The Damen Offshore Carrier is able to handle higher sea states, whilst maintaining course and speed and, by that, being more economical and reliable, he stresses. As well as economical fuel consumption, the vessel can run on HFO380, making it even more cost efficient.

Sustained speed in higher sea states
"Tug-barge combinations are not able to cope with the challenging seas so easily. Deviation from course and reduced speeds can have great impact on the schedule", says Mr Bouma." Therefore, Damen set out to find an alternative. The DOC offers much lower fuel cost and is better able to maintain course and speed, typically averaging 10-12 knots, where a tug and barge would average only 5-7 knots. "There is a definite time advantage; the DOC can keep to the schedule and at a higher speed!"

Reduced fuel consumption: > 50%
Damen's R&D Department's extensive model test programs show that the DOC reduces fuel consumption by 50-75% compared to a tug-barge combination.

In the design process particular attention was paid to the bow and hull form. The new distinctive, sleek bow and slender hull enables the vessel to sustain its speed and course in head seas, as well as helping to reduce fuel consumption. The bow design diminishes accelerations and reduces slamming to a very low level, improving comfort and safety for the vessel, crew and cargo.

Multifunctional
A multifunctional ability was a key part of the DOC design. Damen was keen that it should find deployment in several markets, hence its suitability for shore-to-(off)shore transport, ro-ro operations and installation work.

The large unobstructed deck is free of any manholes, exhaust and de-aeration pipes. Ro-ro operations are unobstructed and modules can be stowed and secured everywhere on deck. An efficient ballast system and the ability to handle ro-ro over the stern and sides are other important advantages.

DP2
The DOC equipped with DP2 will meet the present offshore market demands. DP2 makes the DOC extremely stable for safe offshore loading/unloading operations. DP3 can also be implemented.

The vessel is suited for a replenishment role and could be used for bunkering fuel and other consumables to vessels/installations working in the field as well as for crew exchanges. The DOC can comfortably accommodate 30 people, which can be expanded when in installation mode.

Transport & Installation
The offshore wind and tidal energy markets are other focus areas. The Damen Offshore Carrier can be used in a feedering solution for offshore wind farms, transporting nacelles, transition pieces and monopiles. Its 2,300 m² platform with 20 t/m² load capacity can be used for a wide variety of offshore installation work such as cable laying, subsea installation, reel laying, floatover installation and other methods. For these purposes the vessel can be outfitted with all necessary installation equipment. This can be either a modular solution at a particular stage in the vessel's operational life or an integral solution part of the initial shipbuilding process.

Submersible
Yet another option is the DOC as a semi-submersible vessel, equipped with buoyancy casings. Additionally, the DOC can be fitted with a Damen Deep Dredge giving owners a deepsea dredging and mining solution up to 200 m water depth.

"This really is an ideal platform for a wide range of solutions, we have made the DOC as versatile as possible", says Mr Bouma. "The whole idea is to maximise uptime while reducing cost."

Currently the DOC is 27.5 m wide. Already Damen is considering a larger version of 32.5 m wide. The vessel has a Green Passport and a Zero Dumping certification and the fuel tanks are protected with cofferdams. The first DOC 7500 can be delivered in 2014.