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.
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 work on subsea 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.
The MissionEase system is therefore designed to give vessels a wider operational window to avoid costly weather-related delays on offshore projects, according to Vestdavit.
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.
“In this case we proposed Vestdavit as a supplier due to quick feedback on technical concept proposals, compact size of equipment offered, good experience from earlier projects together, as well as an overall good reputation in the market. The final proposal from Vestdavit met the high-end requirements from Nexans,” says Skipsteknisk’s chief designer for offshore vessels Stig Roe Hauge.
Ulstein Verft purchaser Oda Remøy Reite says: “It was a challenge to find a solution that was space-efficient for the workboat garage and Vestdavit could supply us with a sufficiently compact system in accordance with the shipbuilding specification.”
She adds Vestdavit is “a solid company with innovative equipment that is easy to manoeuvre for the operator”.
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.
Reliable weight data early in the design phase is particularly important as this can affect vessel stability and loading capacity if this data proves to be wrong.
Functional equipment that can be simply connected on a ‘plug-and-play’ basis is also important to ease installation and minimise man-hours at the yard.
Excessive use of man-hours during installation and dysfunction of equipment presents a risk for delays and cost overruns.
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.
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.
“There must be a fluid process to develop and adjust the system also after an equipment delivery contract has been signed to resolve possible design conflicts,” Hansen says.
Skipsteknisk’s Hauge says: “In the concept phase, quick feedback and turnaround time for revised technical proposals is most important.
“In the basic design phase after selection, another key requirement is to provide good-quality technical documentation on time and solution-oriented problem solving”.
He says the Bergen-based davit supplier has demonstrated from previous projects that it can deliver detailed drawings and 3D computer models for the ship designer, as well as “maintain good communication during the design and construction phases to resolve challenges that inevitably occur with such complex equipment”.
Ulstein Verft’s senior engineer responsible for outfitting engineering, Arild Brevik, says the main challenge for the yard in installing MissionEase on the Nexans Aurora was “a lot of measuring”.
“Measurements have to be constantly checked to ensure everything fits and works together, accounting for structural supports above and below the mission deck,” he explains.
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 in the second quarter of this year following final testing, but Vestdavit remains confident of smooth sailing for this flagship delivery.