Barry Towage & Offshore SA, a new Portuguese tug operator with headquarters in Madeira, has taken delivery of the advanced seagoing tug Braveheart.
The vessel is a powerful stern drive tug capable of shiphandling, tanker escort duties, fire fighting, deep sea towing and anchor-handling.
Braveheart is currently working under contract to Total-Fina-Elf, assisting tankers at an offshore FPSO in Angola.
Incorporating several interesting features, the tug was built in Italy by the Rosetti Marino shipyard in Ravenna to a design by Worldwise Marine Engineering (formerly Wijsmuller Engineering) of the Netherlands.
The tug complies with SOLAS and ISM legislation and the requirements of the RINA notation: +100 A 1.1 Nav IL;<$>Re Salvage; FFQ 1; IAQ 1; TPF(1012); Escort Tug Braveheart is a vessel of 39.30m in length with a beam of 13m and a draft less than 5.75m, with a long raised forecastle. The final hull lines produced by Worldwise were aimed at achieving a good escort performance in a vessel with minimum draft, maximum thruster efficiency and minimum trim at reduced loading conditions. As a result the bow has a NACA profile skeg with an end plate, transforming into a bulbous bow, for maximum lateral area and minimum wave resistance. From previous model testing at MARIN (Marine Research Institute Netherlands), WorldWise Marine had discovered that the additional bow skeg can improve the vessel's escort performance by up to 50 per cent compared to a normal stern drive tug.
The flared bow, equipped with a heavy-duty rubber fender, has been configured to avoid contact damage between the underwater bulb and assisted vessels. At the stern, the underwater shape gradually transforms from flat into a V shape giving almost free water flow to the azimuth propellers.
The final hull lines were optimised following wave prediction trials at MARIN using their RAPID programme.
A fendering system made up of heavy moulded rubber sections, supplied by Trellex Trelleborg, is intended to protect the tug in all of its modes of operation. In addition to substantial bow and stern fenders, heavy rectangular section rubber strakes are used to provide protection the forward quarters and sides.
Braveheartt is powered by two 9L26 Wartsila engine de-rated to 2790kW each while running at1000 rev/min, giving a total of 7582 brake horsepower. Power is transmitted to a pair of Rolls Royce US 305 fully azimuthing propulsion units. Each unit incorporates a 3000mm diameter controllable pitch propeller and patented thrust augmenting nozzles.
During trials the tug achieved a continuous bollard pull of 103.3 tonnes ahead at 100 percent MCR and 92.3 tonnes pull astern, figures certified by RINA. While running free, course keeping ahead is reported to be slightly sensitive, as with many stern drive designs, but directional stability astern superb. Maximum ahead and astern speed vary less than one knot with 14.3 knots ahead and 13.5 astern at 100 per cent MCR.
Manoeuvrability is enhanced further by means of a Rolls Royce Kamewa bow thruster capable of producing a maximum thrust of 6.5 tonnes.
The unit has a 1300mm diameter controllable pitch propeller, shaft driven by a dedicated 450kW Volvo Penta diesel located in the engine room.
Volvo Penta engines supplied by Volvo Penta Italy also power generating sets for the vessel's electricity supply, two auxiliary alternators are rated at 215kW each and the harbour/emergency set at 80kW. The engine room is designed for unmanned operation. A Praxis alarm and monitoring system provides all required information on displays in the engine control room and on the bridge. The system includes information from remote tank level sensors.
When shiphandling and working in the escort role Braveheart tows from a Hatlapa single drum, combined winch and anchor windlass. The winch has a 220 tonnes brake holding load and a line pull of 125 tonnes at 10m per minute, a figure now considered marginal in the light of the tug's performance. A Dyneema towline of 64mm diameter and 250m in length from this forward winch can be deployed through a 'Panama' type fairlead in the bulwarks during shiphandling but for escort towing a further low-level lead is provided.
This dedicated 'escort lead' is positioned below the bow fender with the towline passing from the winch to the lead via a stainless steel tube. Significant additional stability is achieved by using the lower lead when high additional steering forces are generated, by the forward skeg and bulbous bow, during escort operations.
A double drum Hatlapa winch is installed within the superstructure aft and used for towing and anchorhandling over the stern. Both drums have a brake holding load of 220 tonnes and line pull of 95 tonnes, and each carry 1000m of 56mm diameter steel wire towline.
The winches fore and aft are fitted with a self-tensioning and towline length monitoring system and may be controlled locally or from the wheelhouse.
Anchorhandling operations are supported with the installation of a 1500mm diameter stern-roller, two 10 tonne tugger winches, two 5 tonne capstans and Karmoy line handling pins and forks. All hydraulic deck equipment is of the low-pressure type for maximum reliability.
An Effer 80000-3 SL knuckle boom crane of 10 tons at 10m outreach is placed above the main winch housing to serve most the after deck area.
A high bollard pull, good manoeuvrability and sea keeping qualities make Braveheart an excellent tug for salvage operations. With this in mind a salvage store is provided on either side of the main winch housing. A spare towing wire is stored on a reel in a further salvage store below deck, aft of the engineroom.
The fire fighting system supplied by Counterfire fully complies with Rina notation FFQ 1. Two pumps, each with a capacity of1450m 3/h, are driven by the main engines via 'step-up' gearboxes and supply two remote control water/foam fire monitors. Each monitor delivers 1200m 3of water per hour, giving a jet of 125m.
During fire fighting operations the vessel can be protected by self-protection drenching system.
Fully air-conditioned accommodation includes a total of eight en-suite cabins.
Single cabins for the master and chief engineer are situated on the forecastle deck, along with the galley and mess room. Two single cabins, three two berth cabins, and one four berth cabin are located at main deck level.
An efficient air-conditioning system, designed for operation in tropical zones, is essential in the tug's present employment.
Separate air-conditioning systems are installed in the main accommodation areas, the wheelhouse and engine control room.
On the bridge, all propulsion units can be operated by means of their individual controls in addition to a single lever 'joystick' system provided by Rolls Royce. Controls for the propulsion system, winches and fire fighting controls, and all major items of navigation and communication equipment are located in two longitudinal consoles. The navigational outfit comprises two radars, DGPS, compasses, autopilot, and electronic chart system.
Communications equipment meets the requirements of GMDSS Area A3 and includes a satellite communications system for fax/voice/data. The entire bridge electronics package was supplied by Furuno and Anschultz.
Currently working with Braveheart in Angola is the Thorax of Ostensjo Rederi another powerful azimuthing escort tug from the same designer.
Both vessels have several features in common, including the 'low tow' point that was first introduced on Thorax a few years ago.