Rod, Several years ago when I was researching what boat I wanted to have as a passagemaker, I found many very good advantages for a catamaran hull and only a few disadvantages. The first disadvantage is transient: it is a developing market here in the states and resale would not be as good for the time being. Also, finding marinas that could accommodate the extra width of a cat might be a slight nuisance. The one disadvantage that kept me away from a catamaran is hull slam in a heavy sea. I know that many cats have anti-slam nacelles to redirect the water, but it still remains a problem. I was reminded of this a week ago in Maui. I was diving with one company at Molokini and noticed a very good looking aluminum cat also conducting dive operations. I asked my captain if he had ridden on that cat in heavy weather? He laughed and obviously figured out what I was getting at. He replied that the boat in question had to be sent to Oahu earlier in the year to have its hull re-welded to the pontoons. Is there anything on the horizon to address this problem with passagemaking catamarans? I own a mono hull with a bulbous bow. When we are cruising in seas heavy enough to lift the bow out of the water, we get bulb slap which is obnoxious in its own right. I am considering moving to a mono hull with a fine entry bow. Phil Eslinger

Phil, Just had to ask since you made the comment about Maui? Do you work for a boating company? Our family will be in Maui in a week and are looking for some boating fun. Mike Pate positivepate@verizon.net On Apr 10, 2005, at 8:03 PM, Phil Eslinger wrote: > Rod, > > Several years ago when I was researching what boat I wanted to have as > a passagemaker, I found many very good advantages for a catamaran hull > and only a few disadvantages. The first disadvantage is transient: it > is a developing market here in the states and resale would not be as > good for the time being. Also, finding marinas that could accommodate > the extra width of a cat might be a slight nuisance. The one > disadvantage that kept me away from a catamaran is hull slam in a heavy > sea. I know that many cats have anti-slam nacelles to redirect the > water, but it still remains a problem. I was reminded of this a week > ago in Maui. I was diving with one company at Molokini and noticed a > very good looking aluminum cat also conducting dive operations. I > asked my captain if he had ridden on that cat in heavy weather? He > laughed and obviously figured out what I was getting at. He replied > that the boat in question had to be sent to Oahu earlier in the year to > have its hull re-welded to the pontoons. > > Is there anything on the horizon to address this problem with > passagemaking catamarans? I own a mono hull with a bulbous bow. When > we are cruising in seas heavy enough to lift the bow out of the water, > we get bulb slap which is obnoxious in its own right. I am > considering moving to a mono hull with a fine entry bow. > > Phil Eslinger > > _______________________________________________ > Passagemaking-Under-Power Mailing List >

Hi Phil, Some of your questions invite answers that may be more subjective than objective. But I'll try to identify which I'm providing, within the text of your e-mail. Phil Eslinger wrote: >Rod, > >Several years ago when I was researching what boat I wanted to have as >a passagemaker, I found many very good advantages for a catamaran hull >and only a few disadvantages. The first disadvantage is transient: it >is a developing market here in the states and resale would not be as >good for the time being. > The good news here is that the "transient" nature of cats that you mention is already passing. In one of the latest issues of PASSAGEMAKER magazine I believe I counted 9 different brands of cruising cats in substantial, display-type advertisements. In just the 5 or 6 years that production-built, cruising-size power cats have been available in the U.S., they've developed as large of a market as it took the sailing cats about 15 years to develop. As for resale value, it appears to me that it's about on a par with monohull boats: the cheaper, more "modestly"-built ones depreciate noticeably -- the well-built ones are reselling, 4 or 5 years after purchase, at approximately the same price their initial owner paid (less taxes, delivery, and options). >Also, finding marinas that could accommodate >the extra width of a cat might be a slight nuisance. > This is a curious situation. It appears that those companies that began as sailing-cat manufacturers, continue to hew to the notion of wide beams when they added power-only cats to their lines. But there's no inherent reason for this. In fact, a visit to New Zealand or Australia will quickly reveal that the majority of their power cats are virtually the same as monohulls when it comes to length/beam ratios. That is, 45' cats there typically have 15' to 16' beams; 60' cats have 20' to 22' beams...just like monohulls. So, if you look around, you're likely to see that you have a choice: power cats with beams that range anywhere from 33% to 50% of the boat's length. Then again, sailing cat owners discover there are few hassles for them when seeking moorage....and any good ocean-sailing cat these days has a beam that is AT LEAST one-half of its length. (Example: Washington state's largest marina currently has about an 8-month waiting list for 40' to 50' monohull slips....yet only 3-4 months for the marina's wider, multihull-only slips.) >The one >disadvantage that kept me away from a catamaran is hull slam in a heavy >sea. I know that many cats have anti-slam nacelles to redirect the >water, but it still remains a problem. > Hmmm....not quite sure what you mean here. There was a time when many sailing cats employed a nacelle, stuck up under the horizontal bridgedeck, half way between the primary hulls at either side of the bridgedeck. Hundreds of Prouts and Privileges were built with this design. In the end, it was discovered that making the bridgedeck higher was a better antidote to "bridgedeck slam" than were nacelles (arcane fact: Gino Morelli, of Morelli & Melvin, designers of Dennis Connors 60' America's Cup sailing cat in '88, and more recently of billionaire Steve Faucet's 125-footer, Plat Station, once told me that the "ideal" height for the bridgedeck of a modern, sail-cruising catamaran that has a beam at least one half its length, is about 5.5% to 6% of the boat's LWL. That means a few inches more than 2-feet for a 45' sailing cat.) But power cats are a different situation. In fact, having been raised for many years as a monohull boater, my first experiences with power cats in relatively heavy-weather conditions were decidedly NON-intuitive. The rougher the conditions (up to a certain extent), the more one INCREASES throttle speed on a cat. Of course, in a monohull, one typically slows as the conditions worsen, to ease the strain on the vessel, but, in particular, to protect ones own kidneys, and personal well-being. But by moderately increasing the cat's speed, one flies even further off each crest, that very act increasing the "cushion" of foam and air rammed under the boat and trapped between the hulls. My first experience of this cushion effect was in about 1991 when I left Ft. Lauderdale on a 42' power cruising cat at the same time as did a 40' sport-fishing boat (the most well-known brand on the market), both of us headed across the Gulf Stream to the Bahamas. Her big, throaty diesels took her away at about 25 knots, while we were cruising comfortably at about 17 knots. Within a half-hour the wind clocked around to the north and increased, bumping rudely against the north-flowing stream. In short order we saw a speck ahead, which soon became recognizable as the 40 sportfisher. By then the wind against the current had turned the seas into those miserable "6-foot blocks" of water for which the stream is so infamous. Understandably, the sportfisher had slowed to about 10-12 knots, if only to protect her crew's kidneys and spines. Meanwhile, though, our cat-experienced skipper had been gradually increasing our speed, to enhance our comfort. By the time we passed the sportfisher, he was smashing along at 10 or 11 knots, and we were zooming along at about 21 knots. I can tell you, that until you've experienced this a few times, your "monohull-experienced brain" keeps saying, SLOW DOWN. And yet, without question, we were more comfortable shooting off those blocks of water at 20-plus knots than at 10 knots. The leap off each block was intimidating, yet each time I expected a nasty slam-landing, we instead were treated to an almost magical "whoosh" as that aforementioned pocket of foam and air cushioned each and every landing. There was nothing special about that design; this is the same phenomenon that has created a large and steady switch among fishermen with trailerable boats -- from monohulls to cats. And there you have a true apples-to-apples comparison, because ALL trailerable boats, monos and cats, hew to the 8'5" beam limitation. So, I'm not quite sure what "slamming" you're referring to. However, if one were to purchae a cat and the horsepower available was minimal, thus restricting the boat's speed, THEN I could imagine that one might sometimes experience bridgedeck-slam. But remember, ALL displacement catamarans (if properly powered) can operate at twice the speed of displacement monohulls (a matter of physics/hydrodynamics, in which two slender displacement hulls have a higher max-speed than does one wide displacement hull). And it's my guess that just about any displacement catamaran, operating at more than about 15 or 16 knots is going to deliver that "cushion" effect in rough conditions. >I was reminded of this a week >ago in Maui. I was diving with one company at Molokini and noticed a >very good looking aluminum cat also conducting dive operations. I >asked my captain if he had ridden on that cat in heavy weather? He >laughed and obviously figured out what I was getting at. He replied >that the boat in question had to be sent to Oahu earlier in the year to >have its hull re-welded to the pontoons. > I can't tell from this brief anecdote what the situation was. But if the new welds held, than I'd say he simply had inferior initial welding....unless he was of the mind that re-welding was something he was going to continually do. But I could also point out that I've had dealings with charter operators and, understandably, they're ALWAYS seeking to generate the highest Return-On-Investment. (i.e., looking to spend the least amount of money for any boat they're putting into charter). And in this quest for best ROI, I've seen them repeatedly accept materials, scantlings, fabrication that were....well, minimal at best. But look at virtually ALL of the best passenger ferries now in operation: Seattle to Victoria, LA to Catalina Island, NY harbor, Hong Kong harbor, Lake Geneva, etc. etc. They're almost exclsusively cats. And they run continually: on a steady shedule, in all manner of conditions, day in and day out. > >Is there anything on the horizon to address this problem with >passagemaking catamarans? I own a mono hull with a bulbous bow. > I'm not a boat designer, but 20 years ago bulbs weren't unknown on cats, either. Even sailing models. However, I've had designers tell me that the greatest benefit of bulbs is on yachts and ships which operate within a very constant/narrow speed parameter. Power cats operate within a much broader speed range, so I'm guessing that's why not a single brand of power cat that I know of uses bulbs. But again, once you're cruising at 15 knots or so, I don't think you're going to find bridgedeck slam any more pronounced than on a monohull....and probably less. (and of course, 15 knots on a cat is at a MUCH lower fuel consumption than on a similar size/speed monohull. For example, a Fountaine Pajot Maryland 37, with twin 140 HP Yanmars, burns about 7 gallons per hour, total. A 46-foot power cat, with twin 330 HP diesels, running at 18 knots, burns a total of 14 gallons per hour. And if you'll accept more sailing-cat-type hulls, you can get down to about 9 or 10 GPH at 18 knots!) >When >we are cruising in seas heavy enough to lift the bow out of the water, >we get bulb slap which is obnoxious in its own right. I am >considering moving to a mono hull with a fine entry bow. > Speaking of which, I noticed that Steve Dashew is offering a REALLY slender monohull power boat. It reminds me of the first quarter of the 1900s. Apparently it was a big deal back then to have even just a 30 or 40 HP engine....and they were REALLY big, physically big. And heavy!. So boat designers, given such limited horsepower, had only one choice: use VERY narrow hulls. The length-beam ratios were sometimes 10:1. Of course, that also makes for a VERY tender vessel. But it also puts the stern wake far behind the transom. In that fashion the designers "fooled the sea" and were able to greatly surpass that normal equation that says the maximum speed of a displacement hull is 3.1 times the sq/rt of the waterline. Of course, even today the Coast Guard's fastest ships use that super-skinny design to "fool the sea." But the boats are TENDER. In the end, that's all catamarans are doing: using super-slender hull ratios, but then eradicating the tenderness by connecting two hulls together. You get the effortless speeds using relatively low horsepower AND a level, no-rock-n-roll ride. Then again, boat ownership is a highly emotional exercise, too. If there's some monohull design that makes your heart go pit-a-pat, then I'd definitely suggest that you get that monohull. It'll make you happier than were you to choose some style (ie., cats) that didn't elicit that same "pit-a-pat." Of course, your happiness-quotient may dip rapidly when one of us cat-men goes "cushioning" past you in heavy seas while you're tenderly babying those aforementioned kidneys! (grin) Wishing you "Cushioned Seas", Rod Gibbons > >Phil Eslinger > >_______________________________________________ >Passagemaking-Under-Power Mailing List > > >

It's amazing what you can learn from an e-mail thread titled "Circumnavigation." Cat's don't depreciate, their beam makes them easier to find slips for, and when the going get's tough, power-up to 20+ knots and be rewarded with a cushy ride. Cliff _________________________________________________________________ Don’t just search. Find. Check out the new MSN Search! http://search.msn.click-url.com/go/onm00200636ave/direct/01/

Rod wrote, "The good news here is that the "transient" nature of cats that you mention is already passing." Your insistent sales pitch is a testament to the contrary! "The length-beam ratios were sometimes 10:1. Of course, that also makes for a VERY tender vessel." This conclusion does not follow from the statement. A vessel is only "tender" if the CG is too high relative to the center of buoyancy. A long L/B vessel can be made reasonably stable provided it isn't too tall. "But the boats are TENDER." This is totally wishful thinking on your part and unsupported by fact. I'm not interested in Cats and I'm tired of you trying to talk me into one. I'm glad that you are so happy with your selection, but they are not the right option for me. Cats are intrinsically wide and I want a "transportable" boat so my maximum beam is 12'. Using your L/B of 3, my beam would limit me to a 36' length. With a monohull I can go up to 65' with a 12 foot beam. What I don't like about Cats is they provide a harsh ride in a beam sea and quartering seas create a torsion load in the deck structure. Many old Cats have failed due to these loads and owners that don't know their limitations. Regards; Mike Schooley