Opposite: the Neel 47 marks the first full collaboration between Eric Neel and the Lombard office (though Neel’s trimaran Trilogic had hulls ‘borrowed’ from an earlier Lombard racing design). Most of the work put into the modern multihull cruiser-racer focuses on two hulls, but given equal investment there is no reason why a modern tri cannot match most of the benefits of a cat while reliably delivering better upwind performance and an easier motion in a seaway. The Neel 47 follows the powerful Joubert-Nivelt designed Neel 65 (left) and the slippery Neel 45 (below)
of buoyancy in the floats of the modern designs together with the increasing size of the ‘average cruiser’. Almost all of the latest big multihulls feature large and comfortable interiors, the result being that (other than for racing boats where displacement continues to reduce) – while overall weights have increased significantly and with modern high-buoyancy floats – the amount of the available stability that is actually used when sailing is in proportion much smaller than on earlier designs. Typically, on a current generic 40ft cat,
when reefed (or not) according to the sug- gested sail configuration (ie the ‘manual’), you’re still only using half the maximum righting moment. On a typical modern 60- footer the percentage becomes lower still, giving an increasing margin of safety before capsize. On today’s biggest multihulls the available stability is so high that you can no longer capsize under the pressure of wind alone; you would first break the sails, and then probably the mast before ever reach- ing maximum righting moment.
Trimaran or catamaran As with the cats, for a modern trimaran the bigger the size the greater the usable stability. However, with the trimaran’s extra width the margin of heel before inversion is even bigger. In Figure A (overleaf) I have plotted a
designs including the two MC34s Courrier Vintage and Nutmeg, the IRC46 Pata Negra and the successful and unusual Ofcet 32. Then there is the Class40 (our Lift 40 won the Route du Rhum 2018) and our latest flying Mini designs 945 and 950. It is the combination of those experi-
ences in yachting and racing that led us to the idea of a new fast and comfortable cruising trimaran. So it was logical for us all to regroup to look once again at the evolution of cruising trimaran design.
The company brief – Neel 47 Modern trimarans first achieved notoriety in the 1970s with the singlehanded OSTAR transatlantic race with the victories of Manureva in 1972 (André Allegre design) and Phil Weld’s Moxie (Dick Newick design) in 1980. But it was the Route du Rhum of 1978 when the three-hull form hit the headlines when Mike Birch’s tiny Walter Greene Acapella design beat the giant monohull Kriter 5 of Michel Mali- novsky by just 78 seconds and stepped directly into the sailing history books.
Since then multihull development of all
types has made dramatic progress and the latest giant Ultim tri perfectly encapsulates today’s idea of the pinnacle racing boat. But if the trimaran became popular as a
racing machine it remained of micro interest for cruising purposes. The image of high-speed racing hindered most attempts at promoting cruising trimarans, the sportive association simply being too strong to reach a large audience. Also not helping was the fact that the traditional narrow and shallow trimaran main hull offered no accommodation at all. If Newick (and Derek Kelsall) did produce some designs that were cruising oriented they only proved of interest to sailors with previous great experience of ocean racing. The stability of multihulls in general,
with the ultimate risk of permanent inver- sion, was a huge drag on early ideas of promoting the breed as a ‘safe offshore boat’. So what has changed, and why are multihulls no longer considered dangerous machines? The main positive factor is the increase
comparison of stability between two multi hulls of the same size, both designed by ourselves: the new Neel 47 trimaran and the Nautitech 46 catamaran. Both yachts are situated in the same perfor- mance range, with moderate overall weights (around 11 tonnes empty and 15 tonnes fully loaded) and similar sail plans. When sailing reefed in 20kt AWS the
stability margins of the two boats are equivalent, but the safety margin in terms of angle of heel is greater in the case of the trimaran. In other words, the trimaran will usually feel more secure when hit by a gust or a particularly steep sea. By contrast, in Figure B (overleaf) I’ve
plotted the same variables but now substi- tuting an old-generation trimaran… a light and narrower boat, with small buoyancy floats, still with the equivalent sail area. The reserve of stability is now a much smaller percentage of the total power used. In other words, those boats function more like racing machines and can become quite unsafe (small stability margin) if not well sailed by experienced sailors.
SEAHORSE 51
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