Roger Hill 48: The Purrfect Cruiser?
By George Sass, Sr.
To say that Jim and Terry O'Hare are boat fanatics is an understatement. Over the years, their waterfront home in downtown Annapolis has been adorned by a variety of beautifully designed, well-built vessels ranging from a high-performance, 53-foot Farr sailboat to a classic 48-foot Ray Hunt motoryacht.
Today their dock sports a down east 38-foot lobster yacht; a 31-foot, twin-outboard catamaran they use for fishing; a Herreshoff Haven 12½ daysailer; and their latest creation, Sea Star, a 48-foot cruising powercat designed by Roger Hill and built by Peter Parvin, both of New Zealand.
Jim and Terry's very first Sea Star was never launched, having been destroyed in a factory fire. They also own Fiesta, a Roger Hill powercat similar in size to Sea Star, which they keep in New Zealand. And before Fiesta and Sea Star, they commissioned the design and construction of a much larger, 58-foot powercat, which they found too big for their needs and sold. Did I say boat fanatics?
The latest Sea Star is the culmination of this couple's tenacious quest for the perfect cruising yacht. Based on my sea trial and discussions with the O'Hares, Sea Star is not only the ideal boat for them, but its overall design and construction may very well define the perfect boat for today's times. In a nutshell, she's fast, stable, quiet, spacious, and nimble. Best of all, she's not a diesel guzzler.
Sea Star's 18-foot beam and twin hulls create so much space that you feel as if you've stepped aboard a 60-plus-footer. Indeed, the O'Hares have entertained 25 guests in Sea Star's voluminous cockpit, which sports a wet bar and built-in barbecue—or barbie, as they say Down Under.
Inside, the yacht's generous beam creates an expansive main saloon with a centerline helm station, and the twin hulls provide a natural and welcome separation between two large staterooms, each with its own head. The guest cabin can actually sleep three in comfort. The galley, located a few steps down from the saloon and open overhead, is bright and cheery. Designed and equipped by Terry, the efficient layout makes it easy to cook while underway, and it shows signs of the O'Hares' sailing background.
Sport-Boat Performance
The big story, though, is this cruiser's impressive performance. As already noted, Sea Star is the O'Hares' fifth multihull, so they're obviously convinced of the advantages of a powercat vs. a monohull. "We've cruised from here [Maryland] to Maine every summer for the past 17 years," says Terry, "and we've always done it ourselves—without crew."
She and Jim find that this size powercat offers a more comfortable ride and greater speed than their monohulled boats while burning far less fuel. Notes Jim, "On our last trip to Maine in Sea Star, we cruised at between 18 and 25 knots. At the low end, 18 knots, Sea Star burns about 13 gallons an hour. When we took our 38-foot lobster boat to Maine, we burned 18 gallons an hour at 18 knots, and that was its top cruising speed," says Jim. "In addition, we have at least five times more living space on Sea Star."
We took the O'Hares' powercat out for an afternoon spin to do some fuel-burn and sound-pressure readings. My first impression was simply how easy it is to spin this boat around in its own length without the need for bow thrusters. Jim demonstrated Sea Star's nimbleness as we waited for the Spa Creek bridge opening. Not having to hear the irritating, grinding noise of a bow thruster is reason enough to like this boat.
Once beyond the harbor's speed limit, Jim opened the throttles of the twin Yanmar 480s, and I felt the exhilaration of acceleration without an appreciable change in the boat's running angle. In a typical planing monohull, the bow rises while the stern digs itself out of a hole. Sea Star doesn't behave like that.
Within seconds we hit 9, 18, 25, and then 30 knots. Looking aft, I saw virtually no wake. Notes Terry, "We've probably startled some boaters as we've gone by because they expect to be rocked by our wake. But then they wave back, surprised they weren't affected by our passing."
Considering how large and commodious this power cruiser is, Sea Star doesn't swallow fuel at a cash-burning rate. At 18 knots the two Yanmars burn a total of 13.5 gallons per hour. At 22 knots the fuel flow is 18 gph, equating to 1.2 nautical miles per gallon. At 25 knots, she burns 26 gph, or roughly 1 nmpg.
And the boat is quiet. In the main saloon at 18 knots, I measured 69 dB of sound pressure, which is slightly louder than a normal conversation. Not bad considering that nearly 1,000 horsepower was pushing us at a very respectable speed. Having the engines located aft, under the cockpit, certainly helps.
The fun part of our trial came when Jim turned the helm hard over to retrace our barely noticeable wake and head back at top speed to make the next bridge opening. There was virtually no lean, and the 48-foot luxury yacht tracked like a Formula One in a hairpin turn. Hmm. If I were a bit younger, I'd bring along a set of water skis next time out.
Designing The Proper Cat
Convinced of the advantages of a twin-hulled design over a monohull, the O'Hares turned to one of the world's leading naval architects and powercat proponents: Roger Hill. In order to understand his design work, you first need to know that, as is the case with monohulls, there are three basic powercat hull forms—displacement, semi-displacement, and planing. Sea Star is a full planing hull, which means that, like its single-hulled
counterparts, the boat gets up ("lifts") and runs on the surface of the water.
The O'Hares' Fiesta is a semi-displacement powercat similar in size to Sea Star. Comparing the performance of these two boats illustrates the basic differences in their respective designs. Sea Star has a higher top end and cruising speed because its hull form creates enough lift to get the boat on plane; once there, adding horsepower increases its speed without significant fuel-burning penalties.
Fiesta, on the other hand, reaches a point where it burns 10-12 gph at about 16-18 knots, an efficient, comfortable cruising speed. Trying to go faster results in a quickly diminishing return. But at its most efficient speed—say, 16 knots—the semi-displacement hull is slightly more efficient than Sea Star's planing hull.
Hill explains the differences in hull design as follows: "A semi-displacement hull has a finer and deeper forefoot, the keel rises aft, and the deadrise [the V] is more warped. Waterline beam is proportionately narrower. A planing hull shape is symmetrical in that the keel is horizontal and straight aft of the forefoot, and the deadrise is reasonably constant aft of midships. The bow is also slightly fuller than in a semi-displacement hull."
But what about the differences in their behavior in various sea conditions? Hill continues: "Comparing 45-foot semi-displacement and planing cats going 10 knots into a five-foot head sea and 30 knots of wind, the ride and comfort level of the semi-displacement hull would be much better. But on the flip side, the semi-displacement hull won't be able to do 25-30 knots in a two- to three-foot chop and feel comfortable while doing it."
Overcoming Multihull Misperceptions
While the performance of today's powercats is impressive, they still represent a small part of the boating market, especially here in the United States. Undoubtedly much of this resistance is due to misperceptions or "old thinking."
Those who venture offshore or cruise in unprotected waters worry about a lack of secondary stability and an increased danger of capsizing. Much of this fear has been born from images of small, capsized sailing cats crewed by thrill-seeking teenagers or news clips of large, ocean-crossing racing cats that have been pushed beyond their limits under extreme conditions. But today's cruising powercats are totally different animals.
To begin with, they have superior initial, stability compared to a typical monohull. As Roger Hill points out, "Try and pick up a sheet of plywood that's lying on a smooth surface. As you lift, the far edge starts to slide away from you because there is very little resistance. This is basically what happens in a well-designed cat. When hit by a large breaking wave, it simply slides out of the way because there is little in the water to
offer lateral resistance, and the hull's stability is quite extreme compared to a similarly sized monohull."
If you're still skeptical, you should also consider how many cats, both sail and power, are delivered on their own bottom, often crossing an ocean to get to their destination. "I would rather be in a storm offshore in one of my cats than in any monohull on the planet," adds Hill.
Another concern among cruisers is that a cat's extreme beam may make it difficult to find a slip. But more and more marinas are building wider slips, as the overall size of yachts has been increasing. "We've never not been able to get a slip," says Jim O'Hare. "A marina usually puts us on an outside pier, which is easy to tie up to, or they give us a slip designed for a larger yacht, a space that can accommodate our 18-foot beam."
Lastly, some less-sophisticated powercat designs have had issues with "hull slap," which is caused by heavy seas hitting the underside of the bridgedeck structure between the two hulls. Hill notes, "It would be very hard to get a planing powercat hull to slap under the wing deck because the bow waves and the compressed air in there have a good cushioning effect.
"Sea Star also incorporates a very shallow prop tunnel that has a wedge in the back of it. This holds the bow down and does not present as much exposed area to the oncoming waves." Jim confirms that he's never had this slapping problem even in rough, offshore seas.
Building Down Under
Sea Star was built by Qualicraft, a small yard in Matakana, New Zealand, about an hour's drive north of Auckland. Qualicraft, which also built the O'Hares' Fiesta, produces just one boat a year with its staff of four. "Roger Hill knew a lot about building with composites from the time he worked with Bruce Farr years ago, and he knew of Peter Parvin at Qualicraft," says Jim. "Since we spend part of each year in New Zealand, we chose to build there, where the yards are more experienced with multihulls."
To achieve Sea Star's impressive performance, saving weight during construction was important. Above the waterline, an Airex closed-cell foam core was used between the inner and outer fiberglass laminates. End-grain balsawood was used as the core material in the decks. For superior strength and reduced weight, carbon fiber laminates were chosen for the bulkheads.
"Using carbon fiber added about 5 percent to the total cost of the boat," says Jim, "but the expense was worth it considering the weight savings. "Lightly loaded, Sea Star displaces just 22,000 lbs. Full of fuel, water, and cruising supplies, that figure rises to 28,000 lbs—still quite light for a 48-foot by 18-foot, twin-engine cruising yacht. "Jim even weighed my dishes before I put them aboard," laughs Terry.
Inside Sea Star, the joinerwork is impeccable, featuring Anigre, a light tan, West African wood. The overall look and feel of the interior is one of uncluttered, purposeful simplicity marked with a touch of elegance. The fact that the O'Hares are such seasoned cruisers is evident throughout. Everything in the boat has a good reason to be there. Terry's galley, for example, is an exercise in efficiency. Located a couple of steps down, in the starboard hull, it's out of the way of saloon traffic, and Terry can easily pass things to guests. A huge freezer is accessible from both the galley and the cockpit.
"We wanted a user-friendly boat that was easy to figure out and maintain," says Terry. Compared to most other modern yachts of her size, Sea Star carries a minimum of complex gear and equipment. In addition to the already mentioned absence of a bow or stern thruster, there is only a single 8-kW generator, just one 12 VDC and one 120 VAC electrical system, no hydraulic stabilizers or trim tabs, and no roof-mounted, hydraulic dinghy-davit system. (The O'Hares' inflatable is easily stored on its side on the broad swim platform.) Again, this couple's years of cruising experience have dictated their desire to keep things simple.
Keeping A Low Profile
Sea Star's superstructure features a low profile, and the O'Hares purposely omitted adding a large, fixed hardtop to the flying bridge. Instead, Jim had Peter Parvin build him a small T-top, not unlike that found on many small, center-console fishing boats. It provides just enough shade for the double helm seat.
"When the weather gets bad or it's too sunny, we drive from below," comments Jim. The result is a handsome looking yacht from all angles, something that can't be said for some other powercat designs. Also, Sea Star's low profile adds to its stability and creates less windage, which in turn helps the vessel's fuel efficiency.
Jim and Terry O'Hare could probably have a 100-footer built if they wanted one. But they've found this 48 x 18 fast cat to be everything they've ever wanted. "We can handle the boat by ourselves, yet the amount of space we have makes it possible to invite guests for extended stays," adds Terry. "We think it's the perfect boat for us."
Having known Jim for many years, I asked him if Sea Star was the last boat he'd commission. With Terry at his side, he said, "Oh, I think so." But there was a mischievous twinkle in his eyes. Somehow I don't believe him.
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