Ulstein newbuild makes splash with innovative davit concept
Newbuild cable-laying vessel Nexans Aurora will be making waves in more ways than one when it hits the water shortly - as it will also mark the launch of the next generation in boat-handling systems, according to the company's release.
The state-of-the-art newbuild, now in the final stages of construction at Norwegian shipyard Ulstein Verft, has been designed specifically to work in harsh-environment conditions and therefore required a boat deployment system with a high level of flexibility and redundancy.
The DP3 vessel, with a cable capacity of 10,000 tonnes, will perform cable-laying, cable system protection and trenching for Nexans Subsea Operations, and its first contract will entail installing export cables for the Seagreen wind farm project off Scotland following sailaway this spring.
Its delivery will also see the operational debut for the first full-scale version of the so-called MissionEase system, developed by Norwegian davit supplier Vestdavit, that represents a significant design leap in launch-and-recovery systems for workboats and other craft carried onboard a vessel for a variety of tasks.
Instead of a traditional davit mounted on the upper deck of a ship, MissionEase uses a system of hydraulic cradles to move boats on a tracking system within a hangar inside the hull to positions for maintenance, preparation or launch using a telescopic davit.
The innovative system installed on the Aurora will have capacity to handle as many as 14 craft - including workboats and ROVs - that can be securely stored and mobilised in the enclosed ‘garage’ on the mission deck.
These will be used to carry out vital maintenance and other work on submarine cables for power supply and fibre-optical communication connected to offshore installations.
Vessel owner Nexans, together with the yard, selected the MissionEase system due to its versatility as it enables multiple boats to be moved around on the mission deck and safely launched from either side of the mothership even in rough weather.
This avoids the risk of shifting weight loads when lowering and lifting boats in adverse weather conditions using a traditional gantry davit on the top deck where space was also limited on the Aurora due to the density of cable-spooling equipment onboard.
Such a system gives the cable-laying vessel a wider operational window so it can continue working on time-critical offshore installation work, avoiding weather-related delays that can have a costly knock-on effect for the client in terms of stalled projects.
A boat-launch system is an essential part of the complex jigsaw puzzle for a newbuild and among the many components that have to be delivered on time and with the correct specifications to ensure timely delivery of the vessel from the yard.
Third-party equipment can account for as much as 70% of the cost of a newbuild and the shipyard is dependent on reliable and timely design, delivery and support from the supplier to mitigate the major share of construction risk that is borne by the yard.
Close collaboration between the ship designer, in this case Ålesund-based Skipsteknisk, and the supplier is vital early in the design phase to avoid technical issues and unforeseen changes during the fabrication phase that can cause costly delays.
MissionEase was proposed by Skipsteknisk during the conceptual phase of the newbuild, given the system was one of very few suitable solutions available in the market that fitted with the vessel’s specifications, with Vestdavit listed as one of the yard’s preferred suppliers.
One of the key challenges during the design phase is to gain a correct picture of the equipment’s dimensions and weight, functionality and connection interface related to elements such as power, cooling and hydraulics so it can be efficiently integrated into the overall blueprint of the vessel, according to Ulstein Design & Solutions’ lead naval architect Terje Våge.
Timely delivery of accurate equipment drawings is necessary and the supplier also needs to provide reliable supervision, follow-up and support throughout the design and construction phases, according to Våge.
In the case of the MissionEase, a particular challenge was to make the system - including its telescopic davits - as compact as possible to fit within a confined space with height constraints on the mission deck, Vestdavit’s area sales manager Martin Hansen explains.
This entailed regular exchanges of digital drawings with Skipsteknisk to eliminate design conflicts when these arose and modify the solution to work around issues such as deck pillars, he says.
Brevik says the interface with Vestdavit has “functioned well” during construction work, supported by digital 3D modelling work on both sides to eliminate anomalies, and the supplier has been on hand to tackle challenges along the way to maintain the newbuild schedule.
While Vestdavit has previously delivered a scaled-down version of the MissionEase for an Esvagt crewing vessel, this will be the first time the full system has been installed on a newbuild and Hansen credits Nexans for the “bold move” in bringing it into real-life operation.
The Nexans Aurora is on track for sailaway at the end of May following scheduled final testing earlier the same month, but Vestdavit remains confident of smooth sailing for this flagship delivery.
