Current work – Outer hull construction

Hull pattern is glimpse of what's coming

Our key focus for some considerable time now has been the outer hull structure. The goal has been to turn our initial concept for this into the real thing. The work has been taking place behind closed doors, with no photos released, as there are aspects of the way the boat is built that are as yet confidential. The BBC is continuing to follow our progress with frequent filming sessions, but the fruits of their labours will not be seen until the boat is almost ready to go on the water. So to lift the lid a little, we've been releasing photos recently – exclusively to this website – that provide a tantalising glimpse of the external size and shape of the boat, and demonstrate the scale of the work that's going on.

When composite materials are being used in construction, as is the case with Quicksilver's outer hull structure, patterns and moulds must be made first, to provide a foundation upon which these materials can be ‘laid-up’ in the desired form. What is seen at the top of this page is the very largest pattern, representing the lower half of the outer hull from the tip of the bow to a point some 25 feet aft. The shape of the bottom and flanks of the boat can be clearly made out, as can the step – a feature on the underside of the hull that will help the boat to 'unstick' from the water and rise up onto the surface, into the planing condition, as it accelerates from low speed to high speed.

This region of the outer hull is delineated by the red line in the CAD image at the foot of this page, which also shows the relative positions of other key elements of the boat, principally the main-hull spaceframe, Rolls-Royce Spey turbofan engine, air-intake module, main sponson-arm and foredeck.

The huge pattern is an outstanding example of the patternmakers' craft. Made entirely by hand with time-honed, traditional methods, it is the work of Millfield Patterns Ltd. in Newcastle upon Tyne. With timber being used throughout, its weight has been estimated at one ton.

One further, far smaller, pattern will be needed for the very front of the boat, and that is the pattern for the chine – a curved lip around the bow that, like the step, will help the boat rise onto the plane. That pattern will follow later, as the chine is to be made as a separate piece that will be added to the hull nearer the time of its final completion.

Engineering properly, not cutting corners

The construction of the pattern seen at the top of this page was but one of a lengthy series of engineering activities that took us to the stage where, at long last, we could make the outer hull of the boat. They have ranged from conceptual design at the very outset to determine the ideal outer-hull shape, to windtunnel testing and hydrodynamic computational fluid dynamics (CFD) analysis in verification, then detailed design work – which included extensive finite-element structural analysis (FEA), some very specialised complex-surfacing work in CAD, and the various stages of selecting and sourcing appropriate composite materials, followed by the manufacture of small samples of the structure for 'three-point' bending tests to destruction to test their strength – and then, finally, impact-testing to assess the outer hull's resistance to striking objects which might be floating in the boat's path when it is at speed.

During the time much of this work was going on, we made the first element of the outer hull structure – the foredeck. That task started with the machining of a high-density foam pattern, from which was cast a fibreglass mould, into which multi-layered skins of carbonfibre were laid-up on either side of a 15mm-thick core of Airex structural foam, producing a very strong yet lightweight foredeck of sandwich-panel construction that will be joined to the lower element of the outer hull in due course.

So, right now ...

The lower portion of the hull is also of sandwich construction, with skins made up of multiple layers of Kevlar on either side of a 12mm-thick core of Baltek, a highly-engineered balsawood material. 'Lay-up' work is currently under way at Quicksilver's  secret 'Skunk Works' deep in rural Lincolnshire. The process involves extensive use of the infusion method, whereby a mixture of epoxy resin and hardener are drawn into the Kevlar fabric under vacuum. The vacuum state compresses the layers of Kevlar firmly together, and is maintained throughout a six-hour curing cycle that results in the fabric hardening to a solid form.

A variety of metallic fittings are being incorporated into the structure during construction to serve as mountings for the outer hull to be attached to the boat's primary structure – the high-tensile steel spaceframe, which has already been built.

The final stages of building the outer hull will involve adding a thin layer of fibreglass to the exterior surfaces and spraying-on a paint system to complete the job.

Among the variety of images displayed on this page is one that shows just a few of the many small samples of the Kevlar/Baltek structure that were tested to destruction before we committed ourselves to manufacturing the full-sized component. Data from the tests were painstakingly scrutinised as part of our efforts to perfect the production process, and there were several iterations, with multiple sets of tests being conducted, before we settled on what we believe to be the best method.

Overall, the outer hull's design and construction is by far the most complex and time-consuming task ever undertaken in-house by the Quicksilver  project, and it has been occupying most of our attention for longer than we would ideally wish. However, the job has to be right first time, so the care and effort being expended is entirely justifable.

Collaboration, a joint effort

Specialists who've contributed to different stages of the outer hull's development include Lorne Campbell (conceptual design), Mike Coulthard (aerodynamic and hydrodynamic CFD), Mark Evans (structural design), Mike Green (conceptual design and windtunnel testing), Tim Harrison (complex-surfacing in CAD), Simon Hart (FE structural analysis), David Johnson (Kevlar/Baltek 'lay-up'), Ed Lupton (carpentry for mock-up pattern), Jeff White (carpentry for mock-up pattern), Bill Woodhouse (assistance with Kevlar/Baltek 'lay-up') and Shaun Wright (patternmaking).

The industrial supporters of the outer-hull build, in addition to Millfield Patterns, are: 3A Composites SA of Sins, Switzerland, who supplied the Baltek core material; Competitive Carbon Composites in Nottingham, who cast the fibreglass mould for the foredeck, then manufactured the foredeck itself; M. Wright & Sons Ltd. of Quorn in Leicestershire, who wove the Kevlar fabric; Trident Foams Ltd. in Furness Vale in the High Peak district of Derbyshire, who manufactured the foredeck pattern; and Wessex Resins & Adhesives Ltd. of Romsey in Hampshire, who manufactured the small structural samples to our specification and strength-tested them, then went on to supply West System Pro-Set epoxy resin and hardener, and a myriad of consumables ranging from vacuum-bag material to mixing-pots.

Our thanks to everyone involved – and to our logistics specialist, Bob Johnson, and the rest of his team at BSJ Holdings in Sleaford, as the task of moving patterns, moulds and finished components from one part of the country to another at progressive stages of the build process is not only exacting but potentially back-breaking at the same time, so it's strictly a job for the professionals.

We'll be issuing further images and information on the outer-hull build shortly.

Images © QWSR Ltd.