Hi Georgs - thanks for the opportunity to contribute - although I can't offer any fearsome stories of power catamarans or power trimarans rolling, despite a number of our designs operating in open ocean storm conditions. Our most well known power catamaran design is the 87' wavepiercer motoryacht "Ultimate Lady" Since her launch in late '98, she has logged around 8000 main engine hours and is routinely traveling 200 - 300 miles from the coast, or undertaking 1000 mile ocean passages chasing billfish. (Incidentally, something like 98% of those hours are private use - she only recently has started to offer charters) Ultimate Lady is often operating in big seas - her skipper recently reporting 7m breaking seas taken on the aft quarter and in excess of 5 m dead on the beam without anything dramatic happening - although they have taken green water onto the flybridge in beams seas. When you consider that the flybridge is 6.5m/21' above static waterline, it offers some insight into the weather conditions required to turn it into a swimming pool.... The biggest she has taken was straight on the bow - the head dropping so quickly down the back face of the wave that fishing rods were flung out of their holders on the transom railing. When you realize how hard it is to get a rod thrown out of a holder in an 18' runabout, it makes me shudder to think of what an 80 tonne, 87' wavepiercer would look like achieving this feat. No damage to boat - only to about 16 egos on board when they all landed flat on their backs.... We have done a lot of work on the 6.5m wavepiercer power trimaran design we are developing (14m, 20m and a 23m version are now in build), which has included trying very hard to trip it up and make something bad happen. We have thus operated it in breaking seas of over 3m at all points of the compass and have never approached anything like a roll over situation. The trimaran appears to be very safe in this respect - because the reserve buoyancy and the waterplane area of the sponsons/amas are relatively low, the response to a roll input is very low and the centrehull is already responding in heave to a beam sea before the sponson has an opportunity to impart a rolling moment. This is definitely borne out in practice - roll angles whilst traveling at speed in a relatively large beam sea remain very low and feels very safe. The 20m trimaran currently in build will be attempting the UIM power boat circumnavigation record attempt and the 23m motoryacht version will be routinely operating in open ocean conditions between Mauritius and Reunion in the Indian Ocean. We are very confident that they are suitable for these applications - indeed, the concept was borne out of the desire to create the ultimate in sea keeping qualities precisely for operating in ocean conditions... I hope that this information is of interest to the forum participants.... Best regards, Andre Moltschaniwskyj Director Craig Loomes Design Group Ltd http://www.cld.co.nz/welcome.htm -----Original Message----- From: Georgs Kolesnikovs [mailto:georgs@powercatamaranworld.com] Sent: 15 April 2005 02:51 To: designer@cld.co.nz Subject: Suitability for offshore service Greetings! There is a discussion under way on the new Power Catamaran List about the capsize factor and the suitability of power catamarans or trimarans for service on the open ocean: http://lists.samurai.com/pipermail/power-catamaran/2005-April/thread.html#13 3 If you have any comments on the subject, I'd be pleased to relay them to the forum. Has there ever been a power multihull capsized that you know of? --Georgs