VT Shipbuilding (formerly Vosper Thornycroft) has completed one of the most demanding technical challenges in nearly 150 years of shipbuilding history with the hand-over of Mirabella V.

The 75m sloop is the biggest single masted yacht in the world and tested VT’s capabilities as one of the leading experts in the field of specialised composite construction.

Besides the hull and superstructure, VT has further extended the barriers of technology with the manufacture of the 90m mast by its subsidiary VT Halmatic.

VT Shipbuilding Managing Director Peter McIntosh commented: “We always recognised that Mirabella V would involve considerable advances in composite boatbuilding technology and the experience we have gained in this project has placed us in an unrivalled position of technical knowledge.

“Mirabella V is one of the most significant ships built by VT in the company’s long history. Our reputation and strength is based on naval shipbuilding but we are proud to have built the world’s most famous yacht here in the UK.”

Designed by Ron Holland, she will carry up to 12 passengers in luxury surroundings with facilities on board including a large wine cellar and an outdoor cinema. Guests will also be able to sail small yachts, enjoy remote controlled replicas of the Mirabella V, ride jet skis and have their own 29 ft motor launch – all carried in a garage at the stern of the vessel. Charter cost will be some $250,000 a week.

Her maiden voyage will be from Portsmouth to Naples and, after crew familiarisation, she will start her charter life in the Mediterranean, switching to the Caribbean in winter.

Mirabella V owner, US businessman Joe Vittoria, added: “The challenge that Mirabella V presented was enormous and I admire VT for taking on such a daunting task, particularly with such little experience in yacht building. However, the result is a yacht that will attract superlatives wherever she goes and it’s a huge credit to all those who have been involved.”

Composite materials were chosen for the yacht due to their light weight and because they offer greater strength, lower maintenance, and durability.

VT has worked closely with designer Ron Holland, owner’s representative Paul Johnson, structural specialists High Modulus, classification society Det Norske Veritas and the Maritime Coastguard Agency in the construction process.

The composite hull started life as a foam cored glass and resin sandwich, but soon changed into a Kevlar, carbon, glass and foam matrix, reinforced with carbon along each stiffener and in way of each bulkhead.

Panels were infused under vacuum in the Woolston panel shop at VT’s former shipyard before being cut to form bulkheads using Mylar templates accurately cut on the VT laser cutter. Laminators from VT Shipbuilding and Powys Yacht Management used their skills to construct the detailed structure around the novel two anchor bow design, and the large garage at the transom of the vessel, capable of accepting a 37 knot tender.

Because of the vessel’s size, much of the machinery and many of the fittings for the yacht have been developed uniquely for Mirabella V. One of the biggest production challenges was the drop keel, which weighs 150 tonnes and is raised by powerful hydraulics to reduce the vessel’s draught.

It is the heaviest lifting fin keel in the world. Capable of lifting six metres into the hull, the fin takes 8 minutes to deploy using a single hydraulic ram.

The 90m hollow carbon epoxy mast, which has a maximum cross section of 1.6 m and structural thickness of up to 40mm, will support some 3400 square metres of sail.

It was manufactured in halves, with the back half comprising two sections and the front half divided into three sections.


The manufacturing process, a similar method to that used in the production of Grand Prix racing cars and the aerospace industry, consisted of layers of carbon reinforcement pre impregnated with epoxy resin. The mast sections were cured using a heat process with temperatures up to 70 degrees centigrade. All five sections were then bonded together before being faired and painted.

Up to 500 kilograms of cabling have been fitted within the hollow centre of the mast, including a mass of sensors to monitor the sail performance. The mast and its components were manufactured by Ocean Yacht Services, Spencer Rigging, VT Halmatic and Formula Spars before being assembled at Southampton Docks by Byrne Longshore.

VT’s design and production team was responsible for the engineering and electrical design on the vessel and the internal systems statistics give an idea of the challenges faced: 110km of electrical wiring fitted to the vessel, 1700 command and control channels, and nearly 7000 pipes combine to supply the power and fluids to the systems on board.

But all of the engineering should go unnoticed by the guests as they enjoy the teak and fabric lined cabins, each with their own individual entertainments system complete with TFT flat screens, satellite communications and DVD players, all integrated with the personnel address system by Ships Electronic Services.

Alternatively, the guests will lounge on sun beds fitted to the cantilevered carbon fibre sky deck, or relax in the forward Jacuzzi or swim in the starboard dip pool, specially designed by Ron Holland to stow the rescue boat and crew tender when on passage below flush fitted decks. The polished stainless steel crane, completed by VT, again stowed below flush fitting deck panels, rises neatly out of its own well to lift both boats over the side.

VT Mirabella V Project Director Rob Carr says: “Designed and built in three years from contract award, Mirabella V will be a landmark ship in all respects, and the experience VT Shipbuilding has gained from this project will shape the way we do business in the future.”

MIRABELLA PRINCIPAL DETAILS

• Length Overall: 75.2m

• Waterline length at full load: 61.0m

• Beam moulded: 14.82m

• Draft (centreboard up) 3.9m

• Draft (centreboard down) 10.0m

• Full load displacement: 740 tonnes

• Inner jib plus main sail area: 2210 sq. m

• Reacher plus main sail area: 2791 sq. m

• Maximum propulsion power: 2 x 788kW at 2188 rpm

• Maximum continuous speed: 16 knots

• Electrical generators (main): 2 x 200kW

• Emergency generator: 1 x 80 kw

VT HALMATIC LTD Portchester Shipyard Hamilton Road Portsmouth Hants PO6 4QB Tel :  +44 (0)23 9253 9600 Fax : +44 (0)23 9253 9601 Website: www.vtplc.com/halmatic/ Email:     seb.freeman@vtplc.com Contact:  Mr Seb Freeman (Marketing)