Mar 8, 2006, 3:10 PM
Post #6 of 14
I really like Peter Johnstone's reply.
Re: [peter johnstone] Mono verses multihull
[In reply to]
Log-In to Post/Reply
I spent so many of the early years ('73-'90) in the multihull business trying to convince the sailing public of their virtues that I just find it difficult to make the argument any more. Thank goodness they are a very accepted design of vessel now.
I was the original importer of the Fountain/Pajot cats back in 1986. I brought a 37 foot 'Louisiane' into the Annapolis show, and then put it into a demo/charter situation on the Cheasapeak Bay. One thing we could ALWAYS count on is selling the wife if she came along. Most women always liked the level sailing. And why do you think the charter companies love them.
Yes, the multihulls do come in all forms, from the sedate cruising ones to the real performance models. Maybe I've slowed down with years, but I always did like the idea of motor/sailers for cruising the world. And the multihull can make a wonderful motor/sailer:
Motor/Sailing Catamaran Concept
(defining ‘the best boat to undertake a world cruise’)
I sincerely believe that a well conceived Motor/Sailer is the most practical, capable, comfortable, safe, economical vessel for serious ocean passagemaking......while retaining the ability to fully explore the most remote, and often shallow coastal regions of the water world.
Even in Beebe’s book,”Voyaging Under Power”, the bible of the power-only crowd, his vessel, “Passagemaker”, was a motorsailer, albeit smaller rigged than he really wanted. Many of the examples he offers as prime passagemakers are instead prime coastal cruisers, ‘semi-displacement’ hulls not optimized for long passages, but rather coastal cruising, where rapid transit is a primary requirement, while fuel use and surviving ultimate conditions are secondary considerations. ‘Trawlers’ today are gravitating toward these semi-planning hull configurations, and twin engines, as buyers become reluctant to accept slow 7-9 knot vessels. And forget wide appeal of primarily sail-powered vessels, particularly with our aging population, so how about those old versatile motorsailers.
We don’t hear much of motorsailers these days....not a popular subject. The old traditional, stoutly-built vessels, with a hefty engine(s), were necessarily compromised in both their sailing and powering statistics. Let’s modernize the motorsailer. The multihull planform holds great promise to improve this breed. The long slender hulls of the catamaran vessel have proven real efficient to push under both power & sail.....not only efficient, but not limited to the traditional slow displacement/length hull-speeds. Just what the motorsailer needs....far less compromising increases in both sail and power performance, while maintaining an economy of operation that truly allows a sea-kindly, long-range capability.
Let’s explore a 40' example. Take the single 120-140 hp diesel used to push the conventional 40' single-hulled trawler or motorsailer to a maximum 8.3 knots hull speed and divide it into two smaller 60 hp diesels driving two long slender catamaran hulls. Voila!, maximum to 15 knots under power with the reliability of twin engines and the stability of a twin-hulled vessel. Add a modest sailing rig to these easily driven hulls, and you now have a passagemaker capable of cruising 12 knots under sail/ power compared with those older 7-knot boats. With 12 knots of speed at your command, you can really take advantage of 'weather windows' to: 1) make your passage as smooth as possible, 2) make some lengthy passages you might never have considered in a slower boat. This multihulled vessel will likely be slowed less by an obstructive seaway, and will accordingly make a passage at almost twice the average speed of the single-hulled vessel...twice the speed for the same total HP. There is an economy of operation here that cuts fuel requirements and bills, and greatly extends their range. In light airs, running one engine often is all that is needed to bring the apparent wind forward to make the sails work harder, and the combination provides much better results than either motoring or sailing alone……
.sailing synergy/harmony, the motor taking over in the lulls and the rig taking over in the puffs.
The sea-kindliness of multihull craft is being rediscovered every day. Continual experiences with whale watching boats, fast ferries, pleasure, commercial, and military applications are all proving the validity of the multihull form. What many people forget about a good ride in a heavy sea is that it is very much a function of weight in addition to hull shape. More weight, more robust, more form resistance it offers to moving thru the ocean, the more the sea acts to resist the vessel's progress, and thus the more uncomfortable ride, and we must slow down. A big headsea is a particular challenge. Heavy boats carry their momentum into each trough and crest in a battle with the sea, while lighter weight vessels with slender hulls slice through with less battering. Per a sign at the Naval academy, “you can out-think the ocean, but you can’t out-slug the ocean.” Modern materials allow for lighter boats, and we must properly distribute the vessel's weight throughout long slender hulls. Following seas tend to pick up broad sterns and slew a vessel off to either side....broach. The catamaran hull does not require these broad sterns.
Storm survivability should be considered at the design stage for any vessel making offshore passages. Loss of power (clogged cooling or fuel filters, restricted air supply, water ingress, etc) often occurs at the most inopportune time (during a storm), and this can put the solely powered vessel at peril in short order. A vessel with a modest sailing rig could save your life, and that of vessel itself. Add a proper sea anchor installation, and I would challenge a hurricane. The catamaran planform was rated ‘best in survivability’ in huge breaking wave tests* carried out by Lock Crowther at the prestigious Univ of Southampton.
Most innovative item on my vessel, the mast-aft sailing rig, also referred to as a ‘single-masted ketch’ ......a marriage between a cutter and a ketch without the mainsail. I have LOTS of data to support my contentions as to the aerodynamic superiority of this configuration.... But lets leave that theory out of the equation for our motorsailing application. The ketch rig is a good small-crew size rig, particularly where all three sails are roller furling!....even a novice could learn to operate this rig.....and she balances under a variety of sail deployments. Lower force centers add safety. Boats with moderate rig proportions tend to make faster overall passages because they are sailed at a higher level of capability than if they carry a lofty hi-performance rig. No big head-bashing booms, and simply wing/wing the headsails downwind. The sail rig contributes damping action to the rolling in a beam/quarter sea (no servo-fins needed), contributes to an unlimited range, and ultimately it will get you home if the engines fail. Ahhhh motorsailing!
Optional nacelle-mounted centerboard precludes any extra hull penetrations, and permits maintenance without hauling-out. ‘Pointed’ deckhouse shape conforms to apparent winds, significantly reducing drag. Flying control bridge & a crows-nest…what a hoot! Dedicated engine rooms, isolated from living spaces. Optional copper-nickel hull material below waterline is impact resistant and naturally antifouling for years.
Accomodations!! How might it appear as a real estate ad?, “Waterfront cottage, 4/5 bedrooms, three baths, large kitchen & dining area, big deck, wonderful views.” Hard to beat a catamaran’s spaciousness and privacy....witness their current popularity in the market. Seamanlike layout... no vast open spaces.
My 65' Motor/Sailing catamaran is the embodiment of a Phil Rhodes’ motorsailer design that has haunted me all these years. Only, this vessel is so much superior. Twin 100hp diesels will cruise her at 12/14knts. Under sail she could make 18/20kts. Range, unlimited. Fuel consumption, extremely low. She could skim over depths as little as 3.5'. Explore those rivers, mangroves, coves, lagoons. Beach the bows. Dive or fish the flats and the reefs from the Bahamas to the Pacific atolls.
THIS IS AN EXPEDITION PASSAGEMAKER!! , 20-25meters, no crew required.