What makes a good catamaran?
What you should keep in mind when buying a catamaran.
What do you think? What are the important features of a catamaran? Tell us about it below in the comments section.
As with all marine vessels, certain features make some catamarans better than others. You won't find a perfect catamaran because no boat is perfect. Compromises are always necessary. But if you think ahead about how you will use your multihull and match your requirements to a high-quality design, you can get pretty close to your dream catamaran.
The crucial attributes to consider for a cruising catamaran are:
Weight bearing capacity
Clearing the bridge deck
Structural integrity and navigability
Windward capacity
Deck surface design
Ease of handling
We will explore each of these catamaran features and how they affect performance, comfort, and ultimately safety.
Early catamaran designs were heavy by today's standards. Multi-hulls were designed with a narrow beam, high freeboard and an inefficient underwater layout. They were prone to pitching and rolling. Today, with technological advances in lighter and stronger composite materials, catamaran performance has improved greatly.
Over the past 20 years, boat builders have thoroughly studied and solved the problems plaguing catamarans, effectively improving their seaworthiness by leaps and bounds. The constant reform and transformation of even the basic principles of catamaran design continues today, as evidenced by the radical catamaran designs of the 2013 America's Cup Challenge (the foiling Gunboat G4 designs come to mind). In fact, many of the problems of older multi-hull designs have been eliminated entirely.
The new generation of cruising catamarans offers exciting and fun sailing yachts with great habitability, space, comfort and safety. This was made possible, in large part, thanks to the pioneers of multihulls.
Catamaran loading capacity
WEIGHT: Unlike a monohull design that can support weight without losing much performance, an overloaded catamaran quickly loses performance and, over time, safety. To counter this, multi-hull manufacturers continually look for ways to reduce construction weight to increase potential payload capacity while still maintaining optimal performance. To select a lightweight catamaran, look for hulls with cored construction and interiors built from lightweight materials. Lighter construction allows catamarans to support more weight and perform faster, so this feature is very important when selecting a cruising catamaran.
Monohulls can heel and cause the wind to scatter when the sails are overloaded, but a catamaran's only available response to the pressure of a gust of wind is to accelerate, so the boat has to be very strong to hold together. The cored construction makes the catamaran strong and very rigid. The rigidity gives the catamaran good performance.
Keep in mind that catamaran hulls are actually two boats joined by a bridge deck. These “boats” are constantly fighting each other and trying to go in their own direction. The boat structure must be strong enough to counteract this while also dealing with the aerodynamic load of the mast in the center of the bridge deck. The catamaran performs an amazing feat in dealing with all the opposing forces inherent to multi-hull design. For that reason, it is critical to ensure that the design and manufacturer are reputable and have a track record that demonstrates structural integrity.
STABILITY: Unlike mono-hulls which rely on a heavy lead keel to keep them upright, a catamaran relies on the beam of the boat and the buoyancy of the hulls for stability. Typically, cruising catamarans will have a beam-to-length ratio of about 50%. Therefore, a 45-foot long catamaran will be about 22 feet wide, providing a very stable platform. Good stability on a catamaran occurs when the righting forces and the heaving forces are in balance. Therefore, if the righting moment is greater than the overturning moment, the boat stays upright. When the overturning moment becomes greater than the righting moment due to an increase in wind, the boat begins to capsize.
This diagram and article by James Wharram, the king of "home-built" catamarans, offer valuable insight into catamaran stability.
Clearing the catamaran bridge deck
All catamarans slam (waves crashing under the bridge deck). It's hard to get used to that noise, which is sometimes disconcerting. The first catamaran I ever sailed on the ocean was a Shuttleworth 44. In the early 1990s and still today, it's considered a good design. However, after a few hours of sailing in rough seas off the east coast of Africa, the slam noise convinced me that the boat was going to break up and sink. Now that I fully understand the nature of a catamaran, it turns out there was no need to worry. I've come to accept that slam is just part of sailing a catamaran. It's the degree of slam that makes the difference between a comfortable ride and a terrifying experience.
Bridge deck clearance is a key factor in predicting the level of buffeting a catamaran design will experience. Greater clearance results in less buffeting. My general rule of thumb is: 4% of overall length is poor, 5% is acceptable, and 6% is good.
As far as impact is concerned, another important factor is weight. If the boat is heavy due to its construction or payload, it will tend to crash into the wave, causing the boat's chest to crash into it. A lighter, more buoyant boat will rise above the wave, which will considerably reduce the Sackville impact. Currie explains in detail the different options, problems and trade-offs.
Windward capacity: catamaran keels vs. daggerboards
The average cruising catamaran has keels, while high-performance cruising catamarans have centerboards. Let's look at the two schools of thought on this topic. The general perception that catamarans can't point as high as monohulls is not entirely true. I have seen modern catamarans that point as high as most cruising monohulls, especially in stronger winds. The question is not how high the boat points, but rather how much room to maneuver it has. A monohull with a large keel (lateral drag) has less room to maneuver than a catamaran with shallow keels. So even if both boats point at 45 degrees, the monohull will track better to windward.
Catamarans with daggerboards can point much better than catamarans with keels. It is claimed that a catamaran with daggerboards is safer because if the daggerboards are up and the boat drifts sideways on a wave, it will ride the wave sideways. Proponents of daggerboards believe that a keel causes the boat to roll when it tries to ride the side of a wave, causing it to capsize.
I can only speak from personal experience. A few days ago in Cape Town I found myself sideways in a 20-foot wave on a 40-foot keelboat catamaran. The boat was hit by three successive waves before we were able to get it back on track. The boat glided through the waves and did not capsize, but some skillful manoeuvring at the helm was necessary. My personal opinion is that both types of boats are safe and acceptable provided they are used correctly.
Catamaran deck surfaces
From a safety perspective, decks should be as wide and flat as possible.
From the cockpit to the mast
Older designs often have two-tiered decks from the coachroof windows to the gunwales, forming a side deck with a trip hazard. Most modern catamaran deck designs are now a flat surface wide enough to walk unhindered from the cockpit to the mast.
Lounge
The cockpit and saloon should be on the same level, with no steps leading down into the saloon if possible. Modern designs have achieved this and it really makes a big difference to ease of movement and safety at sea.
Stern
The stern steps should be wide and easy to climb at a reasonable angle. If the steps are too steep or narrow, they become a hazard and recreational space is lost. The stern should be easily accessible from the dinghy.
Ease of handling: Catamaran deck layout
Deck layout is an important factor because most cruising catamarans are sailed with a short crew. On single-helm catamarans, all lines should be returned to the helm so that there is a static position from which the entire boat can be controlled. I recommend electric winches and single-line reefs at least for the first reef, but also for the second if possible. All of these lines should be returned to the static control station at the helm:
Both jib sheets
The sheet from the opposite side of the boat must be passed through a turning block and through the roof of the car through a clutch to the rudder.
Main sheet
Jib furling line
Single line curl lines
Main halyard
Outhaul
Passenger control lines.
Visibility from the helm is also very important. Visibility in all directions while sailing, maneuvering, or docking is key to the safety of your boat and the property and lives of others. When standing at the helm, you should be able to see both bows, or at the very least the pulpits. The center of the transom from which the anchor is handled should be visible, as well as both sterns for when docking "stern to stern." If you can't see all of these stations while standing at the helm, where the engine controls are, you may run into problems due to blind spots.
Catamaran Features Conclusion
Modern catamaran designs are far more advanced than the early models, which were slower, heavier and underpowered. Problems such as the use of wooden pontoons, bow burying and underpowered rigs have been largely eliminated.
Although composite construction technology offers a huge advantage in terms of lighter materials and sleeker designs, no single design element or piece of high-tech equipment should dominate the vessel to the detriment of the others. With a little compromise, a good naval architect can design a vessel that pleases most people and the result can be very attractive, safe and seaworthy.
Top tip: use a free broker
What compromises should you make when selecting your catamaran? It all depends on what you intend to use it for. Clickandsailing helps both new and veteran multihull owners choose the right boat for their dreams at no cost. The yacht seller pays commissions to the broker, so our advice, gained from thousands of boat purchase transactions, is free for you. We will help you find the right boat, the right program or the right situation.