There Are Several Reasons Why Reverse Bows—Also Called Wave-Piercing—Have Become More Popular of Late. Probably the Most
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TAKE A here are several reasons why reverse bows—also called wave-piercing—have become more popular of late. Probably the most valid of these is the claim T(and generally accepted fact) that such a bow form reduces pitching, which is not only uncomfortable, but also slows the boat. Pitching is aggravated when a conventional bow picks up a large increase in buoyancy as a high wave passes. This throws the bow high in the air, and then it drops back down again in the trough, and the cycle is repeated. Besides the associated discomfort of pitching, the boat is also slowed due to both the added resistance from waves, as well as from the reduced driving force due to the unsteady direction of wind across the rapidly moving mast and sail, since the rig has no choice but to follow the pitching of the boat. 74 MULTIHULLSAILOR - FALL 2014 We know that reverse bows are all the rage on raceboats, but what do they mean for the rest of us? By Mike Waters BOW Photo courtesy of Sodebo FALL 2014 - MULTIHULLSAILOR 75 SECRETS OF THE ICW SEMINAR OCTOBER 12, 10AM-4PM WESTIN ANNAPOLIS, 100 WESTGATE CIRCLE FEATURING Wally Moran ICW Expert and Snowbird Rally Host Mark Doyle On the Water ChartGuides Editor Jeff Grossman & Jean Levine Couples Cruising Experts, TwoCanSail Founders Photo by Matthew B. Jenkins, s/v Alisios SPACE IS LIMITED! SIGN UP TODAY AT sailmagazine.com/ICW TO LEARN THE TRICKS OF A SUCCESSFUL ICW JOURNEY The axe bows (opening spread) on Nigel Irens’s have to be moved farther aft, as a reverse fast,” but I personally believe that we ; Sodebo design, which was designed to be bow may be too narrow to support the generally grow to like the look of any (left) pushed hard by a solo sailor, are a compromise between ultimate performance and ultimate weight of an anchor, windlass and rode, feature that finally proves itself and safety; yet they look radical compared to the but this is not really an issue on catama- performs well. “Beauty is, as beauty plumb bows on his earlier Banque Populaire design (left). This MM65 (top left) shows a pair rans, where the ground tackle is usually does” as one well-known designer once Morrelli & Melvin Morrelli of of swept-back axe bows; this new A-class cat ; located further aft between the hulls. told me. Aesthetics aside, the important (top right) has no-holds-barred reverse bows A third reason to favor a reverse thing is to decide if a reverse bow works (facing ) bow is that it creates less windage. On well for your needs. a large cruising cat this could affect We’ve gone through the positives, Nigel Irens Nigel Irens (right) A reverse bow also allows the longest performance and is also an advantage so let’s now look at the negatives and waterline length for a given hull size and when maneuvering at close quarters in see how they balance out for the type saves some deck weight in the bow. In cross winds. of boat we are considering. First and Peter Nielsen Photos courtesy of by extreme cases anchoring equipment may Some say that a reverse bow “looks foremost, there is the undeniable fact Smartkat – SECRETS OF THE ICW SEMINAR High-Performance OCTOBER 12, 10AM-4PM WESTIN ANNAPOLIS, 100 WESTGATE CIRCLE Sailing Catamaran that Fits in Your Car - 14’ heavy-duty inflatable hulls or Boat! - 65’ sq.ft mainsail, 42’sq.ft jib FEATURING - 20’ mast, all-aluminum frame Wally Moran ICW Expert and Snowbird Rally Host - sets up in 20 minutes Mark Doyle On the Water ChartGuides Editor - 90 lbs total Jeff Grossman & Jean Levine Couples Cruising Experts, TwoCanSail Founders Dealer Inquiries Welcome! 704-560-6385 $5,995 – FREE shipping within the US Photo by Matthew B. Jenkins, s/v Alisios www.smartkatsailing.com SPACE IS LIMITED! SIGN UP TODAY AT sailmagazine.com/ICW TO LEARN THE TRICKS OF A SUCCESSFUL ICW JOURNEY that reverse bows are wet—very wet—as bows. For example, boats that are Axe bows are increasingly seen on they go more through the waves than launched through heavy surf need high performance-oriented boats like this British- built Dazcat (left) and the French-built Bandit over them. On a race boat this can be bows to keep from being swamped 870 tri (right) disregarded, but for a cruiser it could before they even get to sea. Generally make doing a passage in a steep chop a speaking, dryness will win out over miserable experience—even if you don’t pitch reduction for many sailors, as consider the increased risk of being there’s a clear trade-off here. swept off the bow of the boat! And if And what about the reverse bows on you happen to own a catamaran with the new breed of fast catamarans like heavily loaded, there is clearly a large a forward cockpit and wave-piercing the America’s Cup boats? These are ap- forward lever when bearing away that bows, then you can be sure that the pearing on more and more multihulls will tend to stuff bows underwater, and cockpit will at times become nearly and have clearly become fashionable. a reverse bow has far less buoyancy to uninhabitable. I personally have never been totally oppose that force. The very shape of it There are many good reasons why comfortable with this long, slender tends to drive the bow deeper because boats traditionally have large, flared “upside down” bow. When a sail is of the hydrodynamic forces on it. There HIGH PERFORMANCE MAINE CAT 38 Colligo Marine Synthetic Standing Rigging Code/Spinnaker Furlers Deck Hardware Rigging reduced to its elegant essentials. Hot New DESIGN Get use to seeing a lot of these sterns! Fast, Easy, and Single Hand. Awesome Quality. Built in Maine by Wicked Proud Craftsmen. hoW different BoWs Work With a plumb or nearly plumb flareless SECTIONS PROFILES or axe bow, there is slightly less hydrodynamic downward thrust of the bows compared to a true reverse bow, and this can sometimes make a difference. Let’s look briefly at these rough bow sections, representing a conventional, 1 a reverse, and an axe bow. If we drive As the Conventional these shapes forward into waves, we see conventional bow submerges, different responses. (Flare) its flared shape If we now imagine the stem pitched provides buoyancy, but down more, the conventional bow (1) water on top of the flat deck will push it down resists submerging, and slows the boat, until the deck goes under, upon which it will present the large braking surface of the deck to the water—a no-no. The reverse bow (2) will simply continue to drive down under. Meanwhile, the plumb (3) and axe (4) 2 bow will knife through the water without The reverse or Reverse excessive force either up or down, unless wave-piercing the boat turns sideways, when it will start bow is driven down at speed, acting like a brake. Keeping these bows but sheds water moving through the water, regardless of quickly as it rises pitch angle, is clearly very important in avoiding a pitchpole. One also wants to keep the conventional bow’s deck above any solid water and the extra buoyancy will help achieve that. (This primarily The plumb 3 applies to fast, lightweight multihulls, as bow exhibits slower, heavier monohulls are far more neutral behavior Plumb likely to broach). but has extra resistance when Of course, on a cruising boat, no one side-on wants to ever capsize, so you really have to waves to start easing off the sail pressure as soon as the lee bow’s deck gets close to the water surface, something that takes a lot of concentration as well as immediate action. Reefing early will significantly increase your margin of error. One thing of current interest is that 4 the reverse bow moves the greatest Axe volume down low and as shown in the With even less flare, illustration, this can permit an almost flat the axe bow has a very efficient entry bottom up forward. Combined with lifting but also presents foils, this flat surface can be used to a large braking provide early lift to get the bow up. Once surface when side- on to waves up on foils, there is less concern about the reverse bow shape as the bow is now mostly clear of the water. The AC72s of New Zealand, Italy and the USA all used this arrangement to varying degrees. Illustrations by Alastair Garrod; Photos by Peter Nielsen (facing page) FALL 2014 - MULTIHULLSAILOR 79 are many videos of Extreme 40 or AC45 Even on larger boats, protective cuddies Clockwise from above: Wave-piercing bows have a down side as well; the axe bow as seen catamarans capsizing or pitchpoling and coamings will be needed to make on the Neel 45 cruising tri; conservative plumb that show just how quickly a reverse the otherwise wet sailing conditions bows on the pure-cruising Antares cat bow can be driven deep under water, more tolerable. Another way to reduce and how quickly the boat decelerates. pitching is to add a protruding bulb at It seems inevitable to me that these the bow below the waterline, but this is boats must pitchpole if their reverse hardly practical for sailing boats. bows go under with any speed and Which brings us to what has become the straight bow sides as the boat cuts momentum, as happened to Oracle and known as the “axe” bow shape, which through at speed, with a relatively small Artemis last year with quite disastrous is becoming common on larger multi- increase in forward buoyancy.