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Windows of opportunity: The expanding possibilities of on board glass

13 August 2021• Written by Kate Lardy

The possibilities for glass on board are expanding, and the style benefits are crystal-clear, says Kate Lardy

Imagine no boundaries between walls and ceiling, a great expanse of crystal-clear glass where no part of the sea or sky is out of view. The dome-like walls curve outwards beyond the superstructure, glittering in the sun like a jewel and revealing, for those cocooned inside, the raw beauty of nature in perfect clarity. In fact, you don’t have to imagine this, because yacht designers already have.

In the last decade, some long-held tenets regarding the use of glass on superyachts were discarded for a future free of the worries that once held engineers back. Yachts emerged with more glass than had ever been used before. Once owners got a taste for the full-on light and views that these clear barriers offered, there was no turning back. Less structure and more glass is the demand of the day, and there’s further innovation to come.

How we got here

The Steve Jobs theatre, engineered by Eckersley O'Callaghan
Courtesy of Eckersley O'Callaghan

Owners have a behind-the-scenes group to thank for much of the advancement. Consider that the use of glass we are seeing now on yachts isn’t new technology – it is knowledge that has been used on land for years. The problem was convincing those who certify vessels as safe that it would work.

In 2005, a technical committee for the International Organisation for Standardisation (ISO), composed of glass experts along with classification societies and flag states, began working on unified standards for glass. Before then it was more of a case of who was sitting on the other side of the table.

“At the time, if you went to a classification society, you wouldn’t get the same answer if you asked someone from a different classification society. Everybody had the same basic rules but their interpretation was different,” says Henning von der Thüsen, co-managing director of yacht glazing specialist TILSE. “It wasn’t clearly defined what you have to calculate and which kind of tests you have to do.”

The width is the only limiting factor for any type of glass.
Photo by GT Yachtverglasung

The standard (ISO 11336) was published in 2012 and brought chemically toughened glass to the yachting industry for the first time. Before this, the glass type typically permitted was thermally toughened, which doesn’t give as good optical quality.

“There was no standard for defining the material, even if we had used it for 20 years in the industry,” says von der Thüsen, whose company was the first to get type approval for its chemically toughened glass back in 2004. “The standard makes it clear that it was a material that could be used and [defines] how to interpret the different grades of chemical toughening.”

This matters to yacht owners because it’s related to size and weight. In simple terms, chemically toughened or strengthened glass is stronger, thus it can be thinner, reducing its weight, which allows larger panels to be incorporated.

The Jewel Changi airport
Getty Images

Marco Mazzarolo, CEO of glass specialist Viraver, explains: “The chemical hardening process allows us to improve the physical characteristics of the glass, increase the resistance to stress and thermal shock while maintaining – unlike what happens for thermal hardening – an excellent optical quality. This allows us to propose solutions with considerably reduced thicknesses with the same resistance.” After acquiring a new plant in 2018, Viraver can produce chemically strengthened panes of up to eight by 3.2 metres.

The width is the only limiting factor for any type of glass. Glass mills around the world produce plates 3.2 metres wide in a never-ending flow, so they can be as long as is practical. “Normally we use it up to six metres,” explains von der Thüsen. “In special cases up to 18 metres.”

ISO 11336 was published the same year that a groundbreaking yacht was launched: Venus. Designed by Philippe Starck for a man with a distinctive vision, Steve Jobs, the 78-metre Feadship was a virtual glass palace compared to her contemporaries. It featured a clear wall of glass encircling her upper deck as well as bow windows strong enough for head seas and perfectly flush main deck windows.

Venus catapulted glass structural engineers Eckersley O’Callaghan into the yachting arena. The London-based firm has been responsible for Apple’s most interesting structures, like the glass cube of the Apple Fifth Avenue store in New York and the Steve Jobs Theater in Cupertino, California, where – in an earthquake zone – a 41-metre diameter cylinder of glass panels is the sole support for an 80-tonne carbon fibre roof. When others were saying the yacht design wasn’t possible, they came with the attitude: why not?

Artefact's floor to roof glass is a stand out feature
Courtesy of GT Yachtverglasung

“I think naivety was our friend on that project,” says Ian Langham, director of Eckersley O’Callaghan. “We’d ask some probing questions, and then we’d think, how can we improve on that to realise the design ambition? With the support of Feadship we managed to overcome some of the regulatory challenges. People saw that and then thought, ‘Hang on, we can do more with glass than what we’re doing at the minute.’”

Venus’s 15 tonnes of glass walls required about 10 tonnes of hidden aluminium structure, since during her development Lloyd’s was not yet open to the idea of using load-bearing glass. A decade ago it was unthinkable that glass could be structural on a seagoing vessel, subject to loads that no building engineer ever had to worry about. Much R&D ensued and it was paradigm-shifting when glass was accepted as a structural component. This has changed its use dramatically.

Enter another Feadship in 2019, 77-metre Syzygy 818 (now Pi) designed by Jarkko Jämsén with an entire superstructure of glass walls, which in this case arestructural. An incredible 29 per cent of the yacht’s exterior is glass, more than any yacht that has come before or after, says Feadship. The double curved panels, up to 45 millimetres thick, are connected to the ceiling and floor in such a way that the yacht flexes around the glass.

Courtesy of GT Yachtverglasung

What owners want

“Owners today are requesting designs to be much more centred around their needs,” says Marnix Hoekstra, co-creative director of design firm Vripack. “This has led to a completely new way of using glass as a solution to their requests.”

Consider that 97 per cent of the superstructure of Syzygy 818’s owner’s deck is glass. It’s the ultimate answer to a request of many owners: to feel connected to the outdoors.

Curved glass, complex shapes and seamless bonding of the windows, rather than framing, is trending. Greg Marshall, designer of the 2020 yacht Artefact, says that one of the project’s biggest challenges was that the owner didn’t want to see framing around the windows. The 80-metre Nobiskrug features floor-to-ceiling glass that rises over three decks amidships, complementing 740 square metres of curved and artistic glasswork; in total almost 60 tonnes of glass are used in a display of creativity not ever seen before in yachting.

“Behind the scenes is a massive framing structure that is separate from the structure of the boat so it could move differently from the boat… absorbing the difference in expansion and movement,” says Marshall. GL Yachtverglasung (GLY), a yacht glazing specialist, developed a special bonding process for that three-deck tall rise of glass to give the owner a boundary-free connection to the outdoors.

Silent 55, with solar panels and, perhaps one day, photovoltaic glass
Courtesy of Silent Yachts

Owners want that connection to extend below the waterline as well. Naturally, classification societies have been cautious when it comes to sub-sea windows. “The usual challenge is agreeing on realistic safety scenarios with regulators. The last decade has given us better tooling – high grade FEM calculations, better interlayers – to deal with this,” says Bram Jongepier, knowledge and innovation expert at Feadship. His company has again been a leader in the use of glass here. The 83.5-metre Savannah featured a world first when it launched in 2015: a Nemo lounge with three semi-submerged windows of 1.3 metres by 1.6 metres. Each window is actually a twin, consisting of two 46-millimetre glass laminates separated by an air gap.

They have to be super robust, explains Langham. “Sub-sea windows can be 12 to 15 ply thick. I’ve seen some of the testing where they drop huge weights to simulate hitting a shipping container under the waterline, and it only breaks the top two plies.”

It’s not all rose-tinted…

There are downsides to glass as well. The idea of a clear barrier between the owner and nature is terrific if the yacht is perched on the shores of Antarctica or navigating among the deserted isles of Vanuatu – it’s not so ideal at a crowded anchorage.

“More and more owners want less and less structure. They just want to see the world around them,” says Marshall. “The problem is how do you have privacy when you are tied up in Monaco next to a boat 15 feet away? There isn’t really a good solution in place yet. It seems a shame to have vast windows and have to cover them up with blinds.”

Related to the problem of privacy is the solar energy that glass brings in. “For the big yachts where we have room-height glass it is a serious issue to get rid of the heat,” says von der Thüsen. “You can get rid of it by the air conditioning, of course, but this takes a lot of energy and a lot of space. We have had projects where they had to enlarge the ship by two metres to get more space for the air conditioner.”

Vripack's Futura concept
Courtesy of Vripack

“Roughly on an 80-metre boat, you spend $600,000 a year on fuel to run the generators to run the air conditioning. If you can cut out even 50 per cent of the load, that’s a substantial amount of money,” says Marshall.

Tinting windows is the tried-and-tested solution for reducing heat and gaining privacy but some owners are looking for the limitless experience that only clear glass can give. Indeed, Langham notes that clients seem to favour maximum clarity today.

“If you’ve got windows with constant tint on them and you go into a cloud bank, everything looks pretty glum inside,” Marshall points out. He’s been working with glass that automatically tints in response to the sun, so if the rays were on the starboard side, that bank of windows would tint while the port side remains clear. From the inside it looks the same on both sides since the tinting is offset by the brighter exterior.

“The big difference is heat savings. When the glass is dark you can save up to 90 per cent of the AC requirements. That makes a huge difference on a boat like Artefact,” Marshall says.

Savannah's lounge
Courtesy of Feadship

If you don’t want to be at the mercy of the elements, a step up is switchable electric-chromic glass like that used on Boeing 787 windows. “It’s where you have a ceramic layer that’s so fine that you can’t see it; when you apply a small amount of power to it, it goes almost entirely opaque and almost entirely clear and you can go any grade in between. It works beautifully. We looked at it for Artefact. The problem is glass is so expensive that none of the manufacturers were willing to have any foreign products in their glass that could potentially create a liability problem for them,” says Marshall. “Those things will emerge slowly on the big glass pieces. We’re using it a lot on smaller pieces.”

What’s next?

Langham agrees that switchable glass is one promising solution on the horizon. “You had the privacy version of that around for a while, which was used for bathrooms and internal screens, where you can turn it white. This is more specifically giving you a solar performance as well. It actually stops the solar energy from coming into the space when you need it to.”

Another thing Langham would like to see further developed is media glass, incorporating clear televisions: “a window that’s transparent that you can switch on and it outlines what’s on the horizon to describe all the landmarks around you. The technology is already there; it’s just that it needs to increase in scale.”

Marshall sees an application for this in the wheelhouse. “In theory you could have the whole bridge be a series of TVs, and at night time you’re physically not looking through windows but instead looking into TVs.”

Artefact's owner wanted the same glass experience he has in his house
Image by Francisco Martinez

Also on the cusp of gaining traction is electricity-generating glass. Arcadia Yachts has been garnering solar power from glass for more than a decade. On all its models, the superstructure top is a glass sandwich, composed of a layer of photovoltaic cells and a layer of krypton gas, which insulates the interior from the heat. Since the first 26-metre yacht launched in 2010, improvements in solar cells now give 40 per cent more power.

The next step is transparent photovoltaic glass, but the yield isn’t high enough yet for yacht builders to take notice. Silent Yachts, whose catamarans use highly efficient solar panels to supply power for all systems including navigation, says it “aims to implement photovoltaic glass into parts of the yacht in which it makes sense, once they become more efficient,” according to chief marketing officer Franz Böse.

Larger power-hungry yachts are not as good candidates. Jongepier of Feadship says solar applications make a difficult business case now. “Current technology will allow for about 1.5 to two per cent of yearly energy savings by covering a realistic area on board with traditional solar cells. Solar windows have a lower yield due to their required transparency.” He predicts this may change by the end of the decade, though, thanks to developments that increase solar cell yield and decrease a yacht’s power consumption.

“The big difference is heat savings. It makes a huge difference on a boat like Artefact."
Image by Francisco Martinez

Freeform geometry may also be in the future. Think of Singapore’s Jewel Changi Airport with its torus-shaped glass. Vripack has developed a Futura concept with the upper deck based on the principles of a geodesic dome. “Besides giving a very novel look, from the inside to the out you need very low, if not  any, structural support. Because of the shape and the way you’re placing the glass panes, they are actually structurally supporting each other,” says Hoekstra. “To me, it feels a bit like the belly of a whale or something which really sits in the water and effortlessly moves forward.

“Inside, you get this space-like feel when you look to the outside through this wonderful dome,” continues Hoekstra. “The whole world is kind of unfolding in front of you without any visual obstruction. Imagine getting close to a breaking glacier and you’re standing in front of that ceiling-to-floor bump-out pane; you just look up and see the majesty of nature.”

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