Sailboats made from aluminium are meant to sail the hard way. These yachts go, where ordinary GRP-boats usually do not dare: The arctic and antarctic latitudes, the growler-infested Roaring Fourties or other places you would normally not put your plastic hull to a test. Aluminium cruising yachts are the preferred means of transportation for so called “explorational-sailing” and this is often connected to cold temperatures, if not freezing conditions. Heating is a big topic (and I am surely going to make an in-depth article on this one too). And where there´s heat, insulation becomes crucial.
Visiting the Pure Yachts shipyard a few weeks ago, as a coincidence, the Pure 42 drop keel cruising yacht, had just finished the production step of getting her insulation fitted. I found this highly interesting and asked Matthias Schernikau, CEO or Pure Yachts and my guide that day, to show me more details and explain to me how it is done. So, here we go – let´s start at the beginning.
A job for passionate nitpickers
Because before any of the workers could even start to fit a single bit of the insulating cover of the boat, the design office had to churn out a huge amount of data. As you can imagine, no matter which insulating material you want to apply – unless it is sprayed foam of course – you need to have it cut to size. Well, you can either cut each individual tile by hand, accepting considerably inaccuracies and margin of deviation, or you have those tiles cut precise to the millimeter by a machine. As you may have learned by reading my previous articles, Pure Yachts has invested staggering amounts in brand new state-of-the-art cutting- and CNC-machinery.
To get them working, data need to be fed. And so, one of the CAD-designers and shipbuilding engineers at Pure Yachts got tasked to define each single insulation-tile and foam part in form of digital data. It took him several days to finish this job. In the end, the robo-cutter was ready to get fed with the numbers to start cutting several dozens, mere hundreds, of individual insulation tiles. As Matthias explains to me, this effort is worth it because the Pure 42 is meant to become a series production yacht: The one-time spent amount will be profitable with the second unit and onward.
Insulation types for sailing yachts
But why insulating a sailing yacht anyway? If you are a skipper yourself, even if you are only underway during classic summer season, which usually starts in May and ends around late September, maybe lasts as long as October or November, you will surely have experienced chilly nights aboard. I personally get shivers when thinking of getting up in the early hours – even during some Norther European summer mornings – and standing in an ice-cold saloon. Condensed water is dripping, feet are cold. Even if your yacht has a Diesel-forced heating system, it will pretty soon get cold again once turned off. That is because the hull is a huge heat exchanging volume.
Usually, the heat will escape via hull and deck. As the water normally always has 3-4 degrees Celsius minimal temperature, heat loss will also occur, but less. In summer this is insignificant as the sun will pretty quickly heat up the boat. The drying capabilities of our home star are amazing, so usually there is no need to have your yacht insulated if she stays within subtropical and temperate zones. It´s quite different though when you sail up north or to the far south …
Especially metal yachts are prone to quick heat loss because, well you know it: Metal is quite a nice conductor for heat. Even more than a GRP-hull. Insulating steel or aluminium yachts is a matter of course. And so, all of the renown sailboat brands manufacturing aluminium yachts are insulating their boats: I´ve seen it at Allures and Garcia and also at the Alubat location. In the early days, many sorts of insulation materials have been utilized: Cork-based, materials from the construction industry and also sprayed foam that becomes solid. Just like your home-improvement expanding foam. This technique is still valid today and fancied mostly by DIY yacht building projects because it is fast and easy to apply and relatively cheap. Here at Pure Yachts however, they don´t spray. “Never, of course not!”, as Matthias quikly disapproves, shaking his head and smiling: “We are professionals here …”
Pure Yacht´s choice: Armaflex foam
The product Pure Yachts is utilizing is a high-performance and lightweight foam. It´s called “Armaflex” and made by the American company ArmaCell, founded back in 1860 in Pittsburgh, specializing in Cork-products. Later, in 1954, the first synthetic Armaflex insulation foam is produced. Since then, this brand and its products have been at the forefront of flexible elastomeric foams. There are as many as 220 active patents and the product comes in many derivates to meet individual demands.
The kind of soft, but also very solid, foam is pitch black. It has no odor and feels nice when I touch it. The interior of the Pure 42 has already been fitted completely with the insulation. But Matthias points towards a specialty. He says that he personally hates it when looking behind nice facings and discovering ugly things. According to him, this is the fact even on high-class yachts made by luxury brands. You take off a hull panel and behind it it´s pure chaos. “Not with us!”, he says and knocks at one of the insulation tiles fitted to the Pure 42 hull. It´s a real knocking which doesn´t sound like foam at all …
“We have decided to apply a further PVC-layer onto the foam. In white. This ways we achieve a nice, even look and it is just so much more tidy and appealing!” Matthias says that with this extra add-on, the insulation tiling will look absolutely spotless even in 15, 20 years to come if an owner, for whatever reason, will have to take off a facing or a panel to get behind it. “I´ve seen many older yachts with sprayed foam insulation – it starts to peel off, fall apart and crumble away. It looks awful, there´s always these little yellow crumbs of old insulation in the bilge.” It won´t happen on the Pure 42 though …
An insulation is only as strong as its weakest spot
The Armaflex insulation they use aboard this yacht has a thickness of 25 millimeters. Only?, you might want to ask. Well, yes. As Matthias explains, the classic rock wool equivalent of insulating capacity for these 25 millimeters would be staggering 250 millimeters of mineral wool! Can you imagine? That´s quite a powerful insulating material! I mean, it is used for heating pipes and extraordinary industrial applications. That´s quite something! The main bulkhead in the rear of the yacht, separating engine compartment underneath the cockpit deck from the saloon even has 50 millimeters of insulation – partially to cordon off the loud engine sound as well.
But the strongest insulation can only be so strong as its weakest part. That said, Matthias points to the tiny details of this undertaking. It is not just the hundreds of little cassettes, those countless squares filled all along the hull from the bow to the stern. It is also the bare metal stringers and frames. If those would be left out and not insulated, their surface would sum up to a very large area, dispersing precious heat from the inside quite quickly. So these need to be covered in black elastic self-adhesive foam as well. Up to a point when no bare aluminium is visible anymore at all.
This can best be seen at the ceiling of the fore cabin in the Pure 42. Here, the whole cabin is already insulated and “sealed”, as it seems. All spaces and all stringers and frames are covered already, the one still left open will soon be. But why only from the waterline onwards? Why not below the waterline? This has two reasons, as Matthias explains. First, the floorboards which are about to be fitted soon as well will have certain insulating capacities. This reminds me of my shipyard visit at Garcia Yachts where I´ve opened a floor board and saw the thick insulation.
Secondly, even in the Antarctic, the water temperature won´t drop below Zero. There´s simply no need to insulate the area below surface. The whole process of insulating this sailing yacht will also have a very welcome side effect: Armaflex does have sound-absorbing properties as well. So I guess as a skipper or guest aboard this Pure 42 you will not only look forward to sleep in a warm and cozy environment, but also undisturbed by noise pollution from the outside.
Another item crossed off the list
So it´s another detail in this exciting boatbuilding project and production step crossed off the list. More and more, step by step, parts will arrive and will be fitted to the boat. As with my own yacht in the making right now, the production of a ship – no matter its size, design, purpose – is always something magical, something that has its own alluring influence. Matthias says that they will indeed go on and take the extra mile. Cutting corners to speedily finish is not their thing. In the end, the Pure 42 is set to become a dream yacht for sure.
It also shows how much history and interesting facts are hidden behind the bigger and smaller details of shipbuilding there is. I can´t wait to uncover more of them, talk about the little and the huge things, about traditional brands and products, about personal ventures and risky businesses. And surely, I will stay alert to return to Pure the day when something exciting has been done again here. For you, it´s easy not to miss any new article published here – just subscribe to my monthly newsletter and stay informed.
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