Spanish yard delivers offshore newbuildingVessel & ROV News // April 7, 2000
The 60m Remotely Operated Vehicle (ROV) and diving support vessel Midnight Arrow was delivered less than 15 months after the contract to build her was signed, and has already arrived at what will be her base for the foreseeable future in New Orleans, inthe US.
Chartered by Torch Inc, in a long term chartering agreement, she will be engaged in underwater pipeline construction and maintenance tasks. Although basically a supply vessel, she is primarily intended for use as a ROV/diving support vessel.
To this end, she is fitted out to accommodate up to 52 crew, of which more than 40 will be engaged in diving and pipeline work. In fact, says the yard, the design of the entire ship evolved from these primary activities.
The design of the complete vessel, hull lines and steelwork was undertaken by Cintranaval, a well-known naval engineering firm. During the preliminary stages of the design, tank testing was carried out at the Vienna Model Basin, in order to produce a resistance curve for the new design, and ensure satisfactory motions in different sea states. This information was subsequently used to carry out the study of the passive stability tank with which Midnight Arrow is fitted.
Built under the supervision of the American Bureau of Shipping (ABS), Midnight Arrow has provided the Spanish yard with much useful experience, including the advantages of using an NC pipe bending machine, purchased early last year.
In spite of her size, Midnight Arrow is powered by relatively small Caterpillar 3512TA main engines, of 1,297bhp each - the choice of engine also reflects the fact that the newbuilding will not be required to do any significant towing work.
Each engine drives a Schottel STP-101 Twin Propeller through a flexible coupling, the propulsors consisting of two propellers, turning in the same direction, being placed in front of each other on each pod.
One of the advantages of having the blade area shared between two propellers is a reduction in diameter and therefore reduced draft. Control of the Schottel propellers is by means of individual controls, comfortably placed on the main console, at each side of the helmsman seat. These are duplicated in the wheelhouse aft control.
Combined with two electrically driven 350kW Schottel STT 170 bow thrusters the main propulsors give the new offshore ship a high level of manoeuvrability and necessary control for station keeping and tracking when centrally controlled by her Nautronix DPS2 dynamic positioning system. The bow propellers are controlled by means of a joystick, which can control one or both bow thrusters at once, as required.
The shipīs high electrical demand is provided by four generating sets. All four are sited in the auxiliary room, adjacent to the main electrical switchboard room.
Three of these are Caterpillar 3412, 425kW sets, arranged for synchronous operation, serving all the electrical demands of the ship. The fourth Caterpillar 3408TA, 370kW genset is solely dedicated to the operation of the ROVs. There is also a 64kW emergency set fitted on the focīsīle deck, which was supplied by the same manufacturer.
The deck machinery consists of two capstans on the aft corners and windlass forward, supplied by the Dutch manufacturer Ridderinkhoff. These are run by two electro-hydraulic power packs, which have local controls, on deck.
Amongst some of the more notable features of the newbuilding are a large, 45 tonne, 10m outreach crane, supplied by the Norwegian manufacturer Norlift. It has a very large wire drum fitted with a cable length capable of reaching depths of 300m.
Another feature is the aluminium helicopter landing pad, sited over the fore deck. This will be used for the transfer of personnel as well as smaller equipment. Access to the pad is from the wheelhouse top.
There are refuelling facilities for the helicopter as well as fire fighting arrangements, with two monitors fitted on the mast, with the foam liquid being fed from a tank on the wheelhouse top. Water is pumped by means of the on board fire fighting pump.The entire ship has been fitted out with pumps manufactured by Bombas Itur.
Because the ship may in future be operated in very arid areas of the world, the air inlets to the engine room and accommodation have been fitted with sand filters supplied by Heinen & Hopman. The air conditioning plant onboard is designed for operation in tropical zones - the system was supplied and fitted by Grenco.
The accommodation is divided into three levels. Most of the crew quarters are sited on the main deck. The upper deck has a couple of four-man cabins as well as two rooms to serve as ROV control room and project office. The rest is devoted to the galley,mess and food storage, be it dry or cold. The forecastle deck holds cabins for the ship's master and chief engineer, as well as those for the ship's officers and guests.
Midnight Arrow is now on charter to Torch Inc.
Beam (mld): 13.30m
Propulsion engines: 2 x 1.297bhp
Complement: 52 (crew & divers)
Classification: ABS, +A1, Circle E + AMS +DPS2, Survey/ROV/Offshore Support Vessel
Fuel oil: 590m3
Fresh water: 160m3
Ballast water: 290m3