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Considerations when choosing a sailing catamaran

Editor’s note: The following is from Gregor Tarjan’s new book “Catamarans, Every Sailor’s Guide.” Considered an authority in the field of multihulls, Tarjan is president of Aeroyacht Ltd., a New York-based dealership specializing in sail and power cats.

Editor’s note: The following is from Gregor Tarjan’s new book “Catamarans, Every Sailor’s Guide.” Considered an authority in the field of multihulls, Tarjan is president of Aeroyacht Ltd., a New York-based dealership specializing in sail and power cats. Tarjan, who is planning an attempt to challenge the New York to Bermuda powerboat record this year, can be reached at (800) 446-0010 or at His book is available on or on the Aeroyacht Web site, , which features catamaran videos, technical articles and an extensive portfolio of new and used multihulls.

Read the other stories in this package: Cat Power   Catamaran Spec Boxes

Safety and seaworthiness, as Czeslav A. Marchaj describes in his great book, “Seaworthiness: The Forgotten Factor,” should be one of the most important considerations when shopping for a catamaran — in fact, any boat. There will be many parameters to consider when buying a particular cruising multihull, from price and looks to how many she sleeps, but none should be weighed as heavily as seaworthiness. Generally speaking, a seaworthy boat is one that not only has been expertly designed and constructed but that also can show an impeccable safety record.

The concept of seaworthiness is as important for someone who is about to start a circumnavigation as it is for those who stay along the coast or in “protected” bodies of water. But don’t be fooled; even the Great Lakes, Long Island Sound or Chesapeake Bay can get very nasty indeed. Coastal sailors attempting a “hop” to the Caribbean or to Bermuda better be ready to face the worst the ocean can produce. One of the highest waves on the planet was measured in the Gulf Stream, less than 300 miles from shore.

We all know that where the Continental Shelf begins and the waters get shallow near the coast, waves become unstable and tend to break earlier. Consequently it is no surprise that experienced sailors tend to feel safer offshore than close to land. Though most of us are coastal cruisers, the consideration of a tested, proven and seaworthy catamaran should be as important for us as it is for someone who ventures offshore.

Seaworthiness means different things to different people, but most will agree that it encompasses the following: the way the hulls at varying payloads move through the water, the ability to handle waves comfortably and safely at varying points of sail, and weathering storms and bringing boat and crew back to land unharmed.

Well-designed and -built multihulls are among the safest vessels afloat, and in most cases it is human error that poses any danger to crew and boat. By “human” I also mean the builder, which necessitates a close analysis of the boatyard and construction parameters. As can be imagined, a well-designed vessel in experienced hands can still be a suicide machine if it has been slapped together quickly or, as in some cases with high-tech construction failures, has been built by inexperienced, cheap labor under mismanaged conditions. One is lucky if only the ports leak or there are areas of delamination. In the worst cases, the boat might break apart in the most horrendous circumstances. As we all know, catastrophes don’t happen when it’s blowing 15 knots under clear, blue skies. Therefore, when shopping for a boat, the question of construction should be on the very top of the list.

Catamaran construction

Let’s briefly look at the past, at the era before multihull mass production. The acceptance of multihulls in the 1960s and ’70s suffered tremendously by the home-built boats of the time. Plywood and fiberglass, still excellent materials today, were the norm then. Though these have a greater forgiveness to building inconsistencies than today’s high-tech composites, there were enough ill-constructed multihulls to give the vessels a bad image.

Many beautiful Pivers and Searunners, which were excellent designs, still exist. Nevertheless, I would guess an equal number of them that were irresponsibly manufactured simply rotted away at their moorings or fell apart, giving the early U.S. multihull movement a bad start. In some extreme cases people lost their lives due to shabbily constructed multihulls.

Among the early production multihulls were the great Telstar trimarans and the Iroquois catamaran of the ’70s. These British-built vessels were produced in great numbers under controlled conditions, and many are still sailing today. A friend purchased an Iroquois 32 a few years ago, and I had the opportunity to measure the heavy scantlings of the hull. If one can live with the narrow overall beam, the overbuilt and simple Iroquois is a great bargain.

The legendary Wharram cats also must be mentioned. These were mostly home-built by amateurs and represent the simple Polynesian concept of a safe, seaworthy boat. Thousands are sailing today and can be found in every part of the world. I even spotted one in Nepal.

A recent upwind sail on a new 47-foot production catamaran reminded me of the importance of construction and builder experience. The boat was built by a production builder known for narrow, heavy cruising cats. The rig on this boat had been recently tuned, and all shrouds and stays were properly tensioned. We found ourselves sailing in brisk conditions: Waves were about 4 to 6 feet, and the wind was blowing a steady 25 knots and getting stronger. The leeward shroud, which was tight when the boat was at rest, suddenly went extremely slack and was whipping through an arc of almost 2 feet. Not only did this represent a serious injury risk for the crew, compromise the mast fittings and create an inefficient upwind rig, but more importantly it showed the excessive flexibility of the entire structure. The boat would cycle through this athwartship contraction every two seconds, which over the years might eventually do serious damage to the vessel and its entire sandwich structure.

Today’s composite materials allow multihulls to excel as lightweight and strong structures in an often hostile environment: the ocean. But that also comes with a price. High-tech sandwich lay-up and construction must be performed in an absolutely controlled environment. Factors such as resin lay-up ratios, temperature, humidity and pressure are crucial to the strength of the final product. They leave absolutely no room for error or any deviations in working conditions. Remember, a seaworthy boat is only as good as its construction. Yard reputation is as important as the product.

Catamaran design

The design of a catamaran is a beautiful science. Theoretical, practical and intuitive factors are fed into a complex design spiral and weighed against the required compromises. This process is repeated — results updated and fine-tuned — until designer and client decide to stop and declare the result: the final compromise, or the boat.

Good sea boats evolve not only from tank-testing but also by constantly improving and changing the vessel. Often the rig, underwater appendages or parts of the hull are modified to achieve this. Usually if you see at least a dozen catamarans of the same design you can assume that they are good boats. But if you know that hundreds, even thousands of them were built over decades and have heard or read about them in international magazines, it is almost a guarantee of a good product. The final confirmation of seaworthiness might be when one discovers that a particular multihull has won numerous offshore races and awards, as well as having been consistently built in great numbers and whose owners have safely taken them to the most remote parts of the world.

Like seaworthiness, the definition and discussion of good design are complex and mean different things to different people. Different size boats will have to be analyzed using dissimilar parameters — for example how the boat will be used, by how many people, etc. A 22-foot Tremolino, designed by Dick Newick, is a beautiful little trimaran and will be a safe boat to use in a protected bay or even for a day sail along the coast. More experienced sailors will think it safe to venture offshore with her. Taken to the extreme, we all know that the French will take anything across the Atlantic, but I think this is a different story — possibly of Latin heroism.

This is why designers will usually start with parameters such as overall length, payload, operating environment, and the principal purpose of the boat. A 32-foot cat with the same design parameters as a 50-footer probably will have a lesser degree of safety factors simply because of her shorter length and narrower beam. Although the smaller vessel in experienced hands might come through rough conditions as safely as the bigger cat, it will not be as comfortable or “feel” as safe. Which brings me to the following universal truth of sailing, performance and safety: At sea, given equal design and operating parameters, size counts more than anything else — and I mean waterline length. This is why a longer multihull with narrow hulls will usually be faster, safer and more seaworthy than a shorter one with the same weight.

Length is an important consideration regarding seaworthiness, but so is stability and beam. There is a famous misconception about the relationship of a multihull’s overall beam and its dynamic stability. By building narrow hulls one actually increases the relative axis width (distance between port and starboard hull centerlines), which is the only decisive width in a catamaran. Having the same overall beam, a multihull with fatter hulls has a comparatively smaller axis between her hulls than a narrower one. This fact signifies the diagonal axis (the distance from the port stern to starboard bow) of a catamaran as an important design criterion. The longer the hulls and the narrower they are, the longer the diagonal axis will be and the more stable the multihull becomes.

Experience is invaluable in the world of boat design. Catamarans are as different from trimarans as monohulls are from multihulls — different boats, different principles. When I worked with Dave Pedrick in 1984 on Dennis Conner’s legendary America’s Cup 12 Meter Stars & Stripes, he always reminded me: “If it does not break, it’s too heavy.” In the same year I participated in the Olympic Star Class North American Championship, in which Dennis Conner’s margin of beating me and the entire fleet was not only a result of the smallest detail improvements and modifications to his boat but also of his immense experience. Again we see that it is the familiarity, skill and know-how in a particular field that produces winners.

If you are in the market for a cruising catamaran, take the aspect of seaworthiness, construction and design very serious. The brutality of the sea is often forgotten at boat shows or when studying the glossy brochures. In the age of technology, gadgets and globalization, boating is perceived as being safer than ever. Nevertheless the issue of seaworthiness, especially of cats with their higher speeds and loads, should be a top consideration even for a coastal cruiser. Designer experience and a reputable yard are as important as an impeccable safety record for a particular boat. Do your homework. Read all the books you can find on multihulls, and talk to surveyors, authors, delivery skippers and designers. Chances are they will confuse you with their differing opinions. The bottom line: Sail as many dissimilar boats as possible in as heavy conditions as you dare. Common sense will do the rest.