way to do it. Every square centimetre of the hull has been NDTed.’ Like an AC75 or Ultimtrimaran, Raven’s
hull and deck are intermediate modulus (IM) prepreg carbon laminates with Kevlar Nomex honeycomb core throughout, cured in three stages under vacuum at 85°C. Most composite builds of this nature require teams of expert freelance boatbuilders to be assembled, but Baltic Yachts has all of the necessary expertise in house. Only the construction of foils and foil arms was outsourced to a specialist fabricator. ‘When you want absolutely the most
into the unknown. This is a development project rather than a typical custom build and it may take some time for the yacht to reach its full potential. The owner’s team and the yard are quite sensibly unwilling at this stage to make any claims or release any figures about performance. They have, however, shared some key specifications with Seahorse and those numbers make interesting reading. Raven’s light ship displacement is
55 tons, with 9,300kg of ballast. The design waterline (DWL) length of 33.1m is just 90cm shy of the 34m overall length (LOA). Comparing those figures with the recently launched Baltic 110 Zemi – a state-of-the art, high-performance superyacht with 95 tons of displacement, 30 per cent ballast ratio, 33.5m LOA and 31.2m DWL – it’s clear that Raven is a very different beast. Only their beam is similar: Zemi’s 7.6m to Raven’s 7.4m. Design and styling are by the Finnish
designer and naval architect Jarkko Jämsén, who worked closely with the owner to define and refine the concept. While Jämsén is primarily renowned for designing powerboats and large motor yachts, the key players in the technical design team, Botín Partners and Pure Design & Engineering, both have deep experience at the forefront of current grand prix ocean racing and America’s Cup development. An almost full-scale mock-up of the
‘The glazing on this boat was a huge study in itself’
lightweight construction you can’t think about biaxial fibres and rovings and so on,’ Svenlin explains. ‘You have to go for 200gsm unidirectional IM fibre, which is three times as labour intensive. And with the very best quality IM fibre you have to debulk every layer, or at least every second layer. By contrast, with a SPRINT setup you can do it every 10 layers and that’s it, you’re ready to cure. I won’t put any numbers on it but the difference in labour hours is huge.’ The thickness of the hull laminate varies enormously, from very thin in the topsides near the bow to a hundred times thicker or more around the foils. When both of those areas then have to be cured in the same oven
‘it gets pretty tricky,’ Svenlin says. The structural bulkheads and load-
entire boat was constructed and comprehensively checked before the build commenced. ‘In the early stages of the project we also built construction mock-ups in many different shapes to ensure that all bonding would be 100 per cent and followed up with NDT scans,’ Baltic Yachts’ project coordinator Mattias Svenlin explains. ‘That’s the only
bearing panels inside the hull are made with the same high-end composite materials, using a lamination press, and then CNC-milled for a precise fit. The hull moulds were built in carbon to reduce heat differences and thus distortion during the curing process. This produces a near perfect surface on the hull’s outer skin so there is virtually no need to use fairing compound and the paint coatings effectively do the job of filler. Using this
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Raven’s ‘bird’s nest’ guest cockpit structure is composed of load-bearing carbon mullions and acrylic window/lantern panels SEAHORSE 71
EVA-STINA KJELLMAN
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