Attachment: MOTOR SAILERS for PASSAGEMAKER.doc
MIME Type: application/msword

------ Original Message ------ Received: Wed, 20 Apr 2005 05:35:30 PM EDT From: "Malcolm Tennant" <malcolm@tennantdesign.co.nz> To: <power-catamaran@lists.samurai.com> Subject: [PCW] Motor sailers > --------------------------------------------- > Attachment: MOTOR SAILERS for PASSAGEMAKER.doc > MIME Type: application/msword > --------------------------------------------- ______________________________________________________________ Brian replied: I just finished reading Malcolm Tennant's posting "Motor Sailers for Passagemaking", wherein he evolves around to the catamaran hull form as an ideal platform for the modern motor sailor shape. Well we both certainly agree there (reference my earlier posting at the beginning of this forum, Motor/Sailing Catamaran Concept, (defining 'the best boat to undertake a world cruise') <http://lists.samurai.com/pipermail/power-catamaran/2005-March/000006.html> And I would add, we have to give great credit to Malcolm for coming up with a really great underwater hull form for these motor sailers and power cats. His basic form is very nearly a standard in catamarans that employ significant power resources. I was also intrigued with his references to MITseaAH and the 'other' powersailer from New Zealand. For more details on these two vessels, and a discussion of their applicability to the motor sailer concept, I would invite you to visit this forum discussion containing pictures and text, "Monohull verses Multihull powersailers / motorsailers", <http://boatdesign.net/forums/showthread.php?t=4499> that starts with a discussion of the Powersailer 20 from New Zealand. Much further along in this subject tread at posting #76, I introduce my observations on the big new MITseaAH motor sailer <http://boatdesign.net/forums/showpost.php?p=45367&postcount=76> Malcolm, you might consider posting your discussion on this BoatDesign forum as well. ___________________________ Malcolm had written: "Is it possible then to approach this from the other direction? Rather than trying to alter the shape of the sailing hull underway, can we fit sails onto a power boat hull? It is possible to fit sails to a traditional displacement power boat hull?. We have seen that this is exactly what was done in the early days of power. Currently this is often done in the guise of a steadying sail on long range cruising power boats. But again this approach runs up against Froudes Law which limits the performance of a displacement hull under power and sail." Brian had similarly written: (to another proponent of motor sailors, albeit monohulls) "The crux of the problem is when we try to overcome some basic laws of nature in trying to push the monohull form pass it's 'hull speed' in an efficient manner, whether power or sail. Sorry, but it just takes more power and some 'planning surfaces' to do it. Alternatively we can look at pushing longer slimmer shapes that exhibit less hull speed resistance. In the sail mode we have to space these slimmer hulls apart some considerable distance to get stability to carry the sailplan. In the power mode this wide separation is not required necessarily. In the ever-continuing effort to define the term motorsailer, I particularly liked your (Greg Jones) Supreme Court Justice quote, "We know it when we see it". I think this is particularly applicable to the increase in both sailing and powering performance available with the multihull planform over that of the monohull. There are still many boaters that are unwilling to accept these very compelling attributes. As you said, "today's motorsailers are evolving quickly, driven by more knowledgeable owners and designers who derive inspiration from the best boats of the past and improve them with modern design technology and a sure eye." Brian Eiland beiland@usa.net http://www.RunningTideYachts.com distinctive multihull expedition yachts