The use of glass on superyachts

21 January 2015 • Written by Marilyn Mower
Nauta’s Streamline 105 shows an ambitious use of overhead glass for a sailing yacht

Yes, there is far more glass aboard yachts today then ever before, but the glass is still a portal – the access through the structure to the desired view and not the structure itself. Glass is a bit daring; glass is intriguing. There is no other barrier material that connects and separates at the same time. Glass, by its very nature, is unique: neither a solid or a liquid, it is classified by scientists as an amorphous solid.

Considering soaring glass façade skyscrapers such as Dubai’s Burj Khalifa, Taiwan’s Taipei World Financial Center, or The Shard in London, and it’s not surprising that requests for more expansive use of glass are coming fast and furious.

James O’Callaghan of Eckersley O’Callaghan Structural Design, who has designed what are perhaps the world’s most-viewed glass projects – the staircases that are a prominent feature of some Apple stores – says the ultimate goal is an all-glass structure. His glass treads in New York City’s Apple store are 1.8m long and less than five centimetres thick, built of four panels of a laminated DuPont product called SentryGlas Plus.

This is sheet glass formed on an ionomer-based interlayer used for hurricane and bomb-proof applications. Tempered SentryGlas has been accepted by Lloyd’s Register for exterior glass balustrades and windscreens on the Fincantieri cruise ships Ruby Princess and Azura. While a 2005 change in ISO/Lloyd’s rules mandated a switch from simple tempered glass to tempered laminated glass, the previous standard laminate called PVB is 10 kilograms per square metre heavier than the SentryGlas product, which saved 50 tonnes on Ruby Princess.

A cutaway of glass incorporated with the exterior shell of a superyacht by Azure Naval Architects

‘Due to an increasing demand for larger beach clubs, more natural light and a greater connection with the marine environment, we began a project last year to investigate the use of larger glass areas on yachts,’ says Hugo van Wieringen of Azure Yacht Design and Naval Architecture in the Netherlands. ‘Designs with windows from deck to ceiling are appealing, but can cause problems for the strength of the vessel.

‘Our ultimate goal is to use more glass on the superstructure and in the hull; to blur the boundary between interior and exterior spaces,’ he says. ‘Our research has shown that load-bearing glass is not advisable on a yacht due to the dynamic behaviour in a seaway, so our focus has shifted to using glass with an alternative construction method.’

One of the few things glass cannot do is redistribute load. Forces must have a clear load path through glass to structural supports. Even with tempered glass it is important to minimise concentrated loads at connections, so designers must separate glass from metal with a more forgiving material, such as silicon or neoprene. This research has led to some stunning results.

Luiz de Basto’s 90m design for Oceanco features a superstructure completely finished in reflective glass for panoramic full-height views from the interior

Azure’s glass research project has led to a concept that appears as full glass walls on all superstructure decks. This results in great panoramic views, particularly when accompanied by glass bulwarks, without compromising structural integrity.

In addition to using glass on the superstructure, the project is focusing on using glass in the aft areas. Tender garages, for instance, have the potential to be transformed into beach clubs with swim platforms.

Azure, an independent Dutch design office with a staff of more than 20, plans to integrate the results of its research project into its own designs, but will also offer its specific knowledge in this field to partner yacht designers and builders.

Glass can make interesting columns but to keep it from buckling, it must be laminated into bundles – either rods glued together, two laminated tubes of successively small diameter epoxied into a solid hollow cylinder, or as multiple strips bound with resin.

Each of these three processes has been compression-tested to carry a load of more than 3,500kg for a 2.9n column with a diameter of just 10cm. Meanwhile, new glass fin technology is enabling glass to replace mullions in glass walls in land-based construction. Can yachts be far behind?

A cutaway of glass incorporated with the exterior shell of a superyacht by Azure Yacht Design

How far can designers go?

Glass provides superyacht architects with an almost unlimited playing field. Used skilfully, it can alter the external appearance of yachts significantly.

The architects and designers at Blohm + Voss Shipyards had that experience with A – featuring technical and naval architecture by Martin Francis to a concept by Philippe Starck – and Palladium, designed by Michael Leach Design. Francis was the ‘F’ in RFR, a Paris-based engineering firm that invented cable-braced glass wall construction used in IM Pei’s glass pyramid at the Louvre.

‘How the composition of the glass components harmonises with comfort, privacy and safety challenges the expertise of engineers at the shipyard,’ says Matthias Witzel, naval architect at Blohm + Voss. ‘Recognising the interdependencies between the installation location and position with regard to the ship, as well as the interior and exterior effects that may affect a glass structure, is a fundamental factor.

Modern glass shaping techniques give architects the ability to match the curvature of the glass to the structure of the ship. They have more freedom in designing the ship’s contours where glass is concerned. The designs catch the eye and guide it, using coloured glass elements integrated flush with the exterior.’

Espen Øino has used curved glass to great acclaim in Danish Yachts’ Shooting Star

The first yacht to truly establish glass as a design and structural element was Eco, designed by Francis and launched by Blohm + Voss 20 years ago. Espen Øino was a designer on that project.

‘We researched the glass for about three years and were convinced we would get a lot of strength from the geometry of the glass, like an egg,’ Øino recalls. ‘A lot of so-called qualified experts convinced the owner he would need lots of spares for those windows. With unique tint and shape, that tempered glass had to be all made in one run. The yard stored the spare glass for a number of years and to my knowledge, not one of those windows has ever cracked.’

The irony of the project is that the manufacturer for Eco’s convex windows was Flachglas – meaning ‘flat glass’ in German.

‘Glass is a great material, I love to see out. But it’s heavy; you have to find a trade off. We are building a 63m in Turkey for Sunrise and the superstructure is pretty much clad in glass. The thing is, you don’t have to fair and paint glass,’ Øino says. ‘You just can’t use it as a primary supportive structure and the classification societies are getting tougher on glass balustrades and bulwarks.’

The steel-and-glass structure on the aft sundeck of Hot Lab’s 73m Milano project can be a greenhouse, gym or lounge

‘The quality of thicker glass constructions that can be achieved gives designers the ability to attack an issue they have not yet considered. With traditional portholes, the full measure of hull window design has not yet been taken. A 40cm porthole is the standard approach. It is time to take up this issue and include the design of the windows into the design of the hull.

‘Also, the crew and the guests, whose living quarters are often in the hull, need more natural lighting as well as the enjoyment of life that decoratively shaped glass can provide,’ notes Witzel.

Deflecting heat

The problems with glass just now finding a solution are heat build-up and the transmission of glare and UV rays. The US Environmental Protection Agency (EPA) says that heating, cooling and lighting buildings accounts for 36 per cent of US energy consumption. And despite the recession, or perhaps because of it, the US government has been making grants to companies that manufacture ‘dynamic windows’ – panels that can change transparency to help abate heat build-up and glare.

There are two ways to create dynamic windows or ‘smart glass’, as it is more commonly called in Europe: thermotropic and electrochromic. The first is passive, triggered by heat from the sun; the latter requires electrical current to switch the glass from clear to tinted. It can be part of a building or vessel management system, or controlled individually by occupants. Both systems block UV rays.

SPD SmartGlass – used in the studio of ITV’s Daybreak – gives over its looks, heat and glare at the flick of a switch

In the thermotropic arena, one of the largest US manufacturers is Pleotint. It uses a heat-sensitive film sandwiched between two or three panes of glass – and the exterior glass can be tinted or clear.

The film darkens when heated, blocking up to 50 per cent of visible light, while a secondary coating reduces heat transmission through the glass to the inside of a room. The glass stays clear at all times. Because it is passive, only the side of the room in the sunlight darkens. Currently the largest thermochromatic windows possible measure 15.2 x 30.5m.

In the electrochromic sector, Boeing’s choice for its 787 Dreamliner is Sage Electrochromics in Minnesota. In November 2010, Saint-Gobain, the world’s largest manufacturer of building products and second-largest glass manufacturer, made an $80 million strategic investment in Sage to expand the Minnesota plant and enable all its dynamic glass products to be manufactured there, although sold under the Quantum label in Europe.

Flachglas, one of Europe’s largest glass makers in the transportation sector, is also working with electrochromic glass it calls Infraselect, which turns blue to reduce visible light.

Dynamic windows are more expensive than regular windows, with thermochromics at about $15 per square foot and electrochromics $50 per square foot, although the price is dropping as applications and capacity grow.

This bold design by Nuvolari Lenard includes external glass lifts, a retractable glass helicopter hangar, and an infinity pool

Research Frontiers, a New York-based company, has recently developed a SmartGlass controller that allows infinite control of the amount of light that can travel through glass or polycarbonate. Its SPD film contains randomly oriented microscopic particles. When no voltage is present, the particles absorb light and block it from passing through the film. When electrical voltage is applied, the particles align so light can pass through. By regulating the voltage, users instantly regulate the amount of light and heat coming through windows.

This has enabled the world’s first automotive dynamic window called ‘Magic Sky Control’ in the Mercedes-Benz SLK Roadster. At the touch of a button, the roof of this car goes from very dark to clear.

Finally, while some designers are embedding photovoltaic cells into glass roof structures, New Energy Technologies says its SolarWindow technology generates electricity.

The company has coated the clear surface of a working lab-scale prototype with newly discovered, organic electricity-generating coatings, comprised primarily of hydrogen and carbon. These nanotechnology coatings influence electronic, electrochemical and optical properties of the window, producing a highly transparent and aesthetically pleasing soft window tint that earns its keep by making electricity.

Indeed, glass is the material of the future and will be an increasingly important component of interior and exterior yacht design, because it provides almost limitless freedom in design options and the visual freedom yacht owners crave.

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