img629While sailing offshore recently I began thinking about a boat to sail long distances. Particularly, what I had in mind were the long reaches of the Pacific where passages are often thousands of miles and cruising can take you far from supplies for months at a time. The combination of large distances and the need to carry considerable supplies speaks to a catamaran of 55 feet in length.

Most cruising cats of 45 feet have plenty of interior space to comfort a family for extended periods and I felt little need to significantly expand the accommodation layout of a 55-foot cat to the extent often seen in those built for the charter industry. Instead, my aim was to gain offshore sailing comfort, performance and payload capacity while still keeping the boat manageable for short handed sailing.

img627In my previous catamaran designs I have tried several distinct cockpit and deck house configurations. All the Atlantic designs use a cockpit forward of a pilothouse; the Voyager designs have a cockpit aft of a deckhouse; and the Concept 63 catamaran design has a midships cockpit. Having sailed them all in the ocean I've found that they all work and each design has features that are good and features that are not so good. However, at the top of my list for cruising comfort, I would want a real pilothouse as we have used in the Atlantic design series.

There is nothing like the feeling of driving a large, fast catamaran from the midships cockpit of the Atlantic cat design. With complete visibility and all sail controls near at hand, an Atlantic cat fits like a glove. But after a few hours of sailing, in any kind of boat, the time comes to get out of the wind and sun or, if you're unlucky, wind that's dark and wet. Enter the pilothouse &!#8212; this is where the Atlantic Catamaran configuration has no equal. Offering an inside steering and navigation station with an unobstructed view of the horizon all around the Atlantic cats are the epitome of sailing comfort. Standing watch warm and dry in all weather conditions is an addictive experience that had me hooked on my first night offshore (a stormy one) on the original Atlantic 50 cat in 1985.

img6281While the smaller Atlantic cats just don't have the space to incorporate an aft cockpit too, the A-55 can incorporate a "back porch" that greatly expands the living area at anchor and provides a perfect place to carry a large hard-bottom dingy when making passages. This best-of-both-worlds arrangement makes the Atlantic 55 truly unique and extremely functional.

Down below the accommodation plan is designed for offshore sailing. All the bunks are located well aft where the pitching motion is least. Each hull contains a large head and shower that serves the occupants of two double cabins. A borrowed feature from the Voyager catamaran design is the magnificent double bunk aft cabin that is very comfortable and quiet while sailing.

The galley is much like the galley of the sister Atlantic cats. It is located amidships in the starboard hull where meal preparation does not interfere with the watch keeping and the cook can easily brace him or herself in rough weather. At anchor there is good visual communication between the galley and pilothouse so that there is no need to feel isolated in the galley. Lots of counter space and stowage is incorporated within the galley. And for long term sailing a dedicated pantry is located in the starboard hull forward ... where else can you store a case of tortilla chips?

img626The port hull accommodations are a mirror image of the starboard with the exception of the galley. Instead, a work bench and tool stowage is built into the hull adjacent to the steps from the pilothouse. Outboard a large locker holds foul-weather gear, seaboots, harnesses and other bulky items.

The sailplan is more a double headed sloop than a cutter. The idea here is to have a large genoa for use running and reaching. In strong winds and squalls the genoa is easily rolled away and the smaller working jib used. The working jib is roller furling/reefing and is also self tacking by means of a club foot. This makes short tacking the boat a pleasure and means the jib can be used for deep reaching and running in rough weather without backing and filling. Sail area is ample for excellent light-air performance. In favorable, consistent weather 300 miles a day can be achieved with reasonable comfort.

Windward performance and crisp tacking is assured by centerboards. The centerboard trunks are all beneath the cabin sole and do not get in the way of the cabin at all. The centerboard emerges from a shallow "belly fin" on the hull. The belly fin gives protection to the hull bottom, propellers and rudders in accidental grounding or intentional beaching and is an arrangement that we have used in all the Atlantic cats with excellent results.

Cruising sailboats do a lot of motoring and motorsailing in very light winds. The A-55 can carry twin diesels of 50 to 100 horsepower. My choice would be for a naturally aspirated engine such as the Yanmar 4JH3 (56 horsepower). A pair of these engines will push the A-55 to 10 knots at 2,750 rpm cruise and nearly 12 knots wide open. More powerful engines could yield cruising speeds up to 14 knots. With 100 gallons of fuel per engine range under power (which varies depending on conditions and speed run) is approximately 1,000 miles at normal cruise and can be stretched to 1,600 miles by alternating engines and running slower (about 8 knots). Given the excellent light-air sailing performance of this design and the consequent reduced need to motor the range under power is considerable. For comfort offshore the height of the underwing above the water it is about the most important consideration in the design of a catamaran. I don't think there has been a cat yet designed with too much height in the underwing, most are WAY too low and that will insure disagreeable pounding.

The Atlantic 55 has nearly 3.5 feet of clearance to the bottom of the wing! To put this in perspective, it is about 10 percent greater than the already generous clearance of my Concept 63 design. While the occasional wave slap cannot be eliminated, the crew of the Atlantic 55 will find these events to be infrequent.

img625Safety is my first concern in the design of a boat to sail the oceans. The Atlantic 55 is ruggedly constructed using durable and fatigue resistant materials. Her hull scantlings are more robust than normal on the assumption that this boat will be sailed hard for long distances with a heavy load. Pivot-up centerboards retract upon impact or grounding and are much less likely to be damaged than daggerboards. The rudders and propellers are protected from grounding damage by the hull fin and the rudders are built particularly strong in order to resist damage from striking floating debris. Offshore sailing safety is very much tied to the crew remaining rested and alert. The pilothouse configuration does this better than any other, in my opinion, because the "on watch" can always be dry and comfortable by selecting either the inside or outside helm. The most common danger in sailing is man overboard. Atlantic cats have probably the safest sailboat cockpit ever devised. Their deep center cockpits with 10 feet of deck on either side are extremely secure. All sail handling can be done from this position because the mast is in the cockpit! Need to reef? No problem, it's all right in the cockpit. I could rest comfortably letting my children steer a night watch from this position, in stark contrast to some cats I've seen with the steering perched on the transoms which is asking for trouble offshore.

In severe conditions the Atlantic 55 incorporates all the proven design elements to permit the highest level of sailing safety. The most important features are:
1. Having enough overall beam for stability in storm conditions.
2. Adequate freeboard and hull volume, particularly forward.
3. A low center of gravity. Heavy items and tanks should be as low as possible. The rig not too tall and not excessively heavy.
4. Light to moderate weight consistent with the size of the vessel. Overweight is dangerous!
5. Correct longitudinal distribution of weight that allows running fast in large waves without burying the bows.

Two watertight collision bulkheads are built into each hull bow. A third bulkhead separates the engine space from the hull in order to contain flooding should a major leak occur there. And no matter what happens the Atlantic 55 cannot sink. She is built with thick foam cores in hulls, crossbeams and decks that yield approximately 20,000 pounds of floatation. Of course in a cat there is no ballast keel trying to drag the hull to the bottom of the ocean.

For ultimate offshore safety the first 14 feet of one of the hull bows can easily be set up as a "habitation module" that can be livable right side up or up-side down. This area can be sealed off and pumped dry and is equipped survival gear and rations, ventilation and hammocks which would allow the crew to make do for as long as necessary in the event of capsize, major collision damage or other catastrophe.

The Atlantic 55 is now building by Bongers Marine near Cape Town, South Africa. Bongers has extensive experience in composite construction and a history of building offshore cruising boats. Hulls and deck laminates are vacuum bagged in foam cored epoxy/glass using epoxy resin. Crossbeam laminates are unidirectional carbon fiber. Finish and equipment are all first rate.

Interior configurations can be modified to suit individual owners. Currently, both a galley down and galley-up versions are available. In addition, the original concept of an open dinghy deck located behind the pilothouse has been modified for one owner to a conventional aft cockpit for lounging at anchor. The Atlantic 55 ready to sail with normal equipment, excluding sails, starts at $599,000. (Introductory price, March 2000, full details on request)

Chris White Designs
5 Smiths Way
S. Dartmouth MA 02748
phone: (508) 636-6111
fax: (508) 636-6110
cwdesign@ma.ultranet.com

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