Boat U.S. - September 2008 - (Page 36)

Aluminum hulls when properly constructed and protected from galvanic corrosion (more on this later) can easily last a lifetime. As the owner of a 30-yearold Marinette aluminum cruising boat, I can attest to this. Jeff Rhodes, president of Coastal Craft, one of the few aluminum cruising boatbuilders in North America, agrees. “The biggest advantage is longevity,” says Rhodes. “When you start with a solid, sound structure, your initial investment is sound.” Another economic advantage, better fuel economy, comes from aluminum’s weight savings over fiberglass. “For equal-strength yachts in the 40-foot range, the weight savings would be substantial,” says Rhodes. “The aluminum boat would be 10-20% lighter if you are comparing hulls of the same strength.” Lighter boats can be powered with smaller engines. In contrast to the 30- to 34-foot fiberglass cruising boats owned by friends at my marina, which typically are powered with a pair of Chevrolet-derived 454-cubic-inch displacement V8s, my boat is powered by a pair of 318-cubicinch engines. Consequently my fuel burn at cruise is about one third lower than theirs. Lower burn rates allow for smaller fuel tanks, and smaller engines also increase the space available in the boat for other uses, such as extra storage or a bigger stateroom. Coastal Craft has taken the next step in space and fuel savings by offering their 420 model with Volvo IPS poddrives. “It’s a remarkably clean installation with IPS,” says Rhodes. “So many systems tie together with the IPS thanks to the electronic engine controls. It’s really nice for the designer/builder and the customer is seeing huge advantages as well.” Volvo’s integrated engine controls on IPS drives allow for multiple steering stations to be installed, and can interface with autopilots and trim tab controls. Coastal Craft’s 420 with IPS 600 drives, outputting 435 horsepower, tops out at 34 knots at wide open throttle and cruises at 28.5 knots. The 420 achieves better than one nautical mile per gallon at all cruise speeds between 20 and 28 knots and around three nautical miles per gallon at eight knots. By contrast, a 42 Sabreline Express powered by 440-hp Yanmar engines with traditional shafted-inboards tops out at 29 knots and cruises around 25 knots, getting around 0.8 nautical miles per gallon. An aluminum hull can also provide peace of mind. It’s high strength and ability to deform significantly before failing means it is less likely to be breached in a collision. This durability makes aluminum the hull material of choice for many government and commercial vessels as well as for fishermen who ply shallow rivers full of rocks. Aluminum however, does have a major weakness in that it is one of the least noble metals and thus highly susceptible to galvanic corrosion. Anytime two dissimilar metals are immersed in saltwater, the less noble

Table of Contents Feed for the Digital Edition of Boat U.S. - September 2008

Boat U.S. - September 2008 Contents Behind The Buoy BoatU.S. Reports Member Forum List Locker Aluminum Can Do Cruising in Crossovers Second Guessing Seasonal Forecasts A Cradle for Your Baby Badlands Boating The Inns and Outs of Penobscot Bay All in the Family: The Butler Did It Stealing Back Peace of Mind DIY Boat Owner Files Good Foundations Boat Smart 2nd Time Around Hot Tips Tangled Line Seaworthy Ask Chuck At Your Service BoatU.S. Exchange Behind the Boat Where Our Flags Fly

Boat U.S. - September 2008

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