Design
RM hulls are built without any moulds. The multi- chine shape is inherently stiff and it adds a useful bit of extra form stability
are basically the same. Then you’ll see something like an RM yacht and realise that it’s not true at all. Distinctly different from most of their peers in both concept and construction, RMs have earned a reputation over 35 years for being practical and durable, seaworthy and fast. Most of today’s cruising boats have hull
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features loosely derived from ocean racing. It’s now the norm to have broad aft quarters with hard chines for extra form stability, twin rudders, a shallow bilge and a high-volume bow. Mast steps are moving aft in the hull. What sets RM apart from most other builders, as the shipyard’s commercial director César Dohy explains, is a very strong emphasis on ensuring their boats’ displacement remains light enough to take advantage of these design features. Despite being a blue water cruiser the RM 1070 for example has the same displacement, ballast ratio and sail area : displacement ratio as a typical offshore racer-cruiser of the same length. One of the key factors in achieving
alking around a boat show or a big marina, it’s easy to conclude that all modern cruising yachts
lighter displacement is that RMs are built in epoxy-plywood with foam sandwich decks. Contrary to what you might expect, epoxy-ply has a very high strength-to- weight ratio. Some of the weight saving is used to strengthen the boats’ internal structure, which includes a steel frame that bears nearly all rig and keel loads. The multi-chine shape of an RM hull is inherently stiff and like a racing boat the internal structure is laminated to the hull, rather than set in place with mastic like a typical GRP cruiser. The first RMs from the late 1980s are still sailing with no structural issues, which says a lot about their longevity. The current boats are even more durable. The ease of repairing plywood is a big
scale builders are, Dohy explains, ‘but it’s not good for high-volume industrial production because you have no moulds. Making 10 boats or 200 will be the same cost per boat; it’s quite close to a one-off building technique.’ A key strength of the RM brand is that
‘RMs have a reputation for being practical, durable and fast’
all of its hull shapes, sailplans and deck plans have been developed and incrementally refined over three and a half decades by the same design team, which
advantage for blue water cruising. ‘Most of the world’s fishing boats are wooden so the repair techniques are well-known everywhere,’ Dohy says. ‘Or you can do it yourself with plywood and glue. For temporary repairs you don’t even need epoxy. You can use Sikaflex, which is useful because even when it’s wet it can stick.’ How come other yacht manufacturers aren’t using epoxy-plywood? Many small-
just happens to be one of the best in the business. Marc Lombard’s achievements in current ocean racing innovation speak for themselves. And it was Lombard, right at the outset, who suggested epoxy-ply as the optimal building material for RM yachts and designed them accordingly. True to their focus on offshore voyaging,
RMyachts are optimised for downwind performance. ‘We have very precise numbers on wind angles through the Grand Large Yachting group,’ Dohy says. ‘Some Outremer cats went around the world and recorded all of their wind angles. They were sailing upwind not even 10 per cent of the time, because when cruising you have the time to wait. The plan is not sail upwind across the North Atlantic.’ The Lombard design office has put a lot
Far from a typical cruiser. RM yachts don’t just look different, they are different in many ways
70 SEAHORSE
of R&D into a new generation of twin keels, designed specifically for RMyachts. Twin (or bilge) keels have been out of favour in yacht design since the 1980s when they were notorious for poor windward performance. Lombard’s short-chord, high- aspect twins are a huge improvement on the traditional type with a lotmore righting moment andmuch better hydrodynamic
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