Catamaran Hull Configuration
The hull configuration of a catamaran is simple and easy to identify. Catamarans Have a wide stance and consist of two identically shaped narrow hulls connected at the tops. The hulls are an exact mirror of each other, and there's a large space or platform in between them that provides room for a cockpit, living spaces, and even a trampoline.
Catamarans vary widely in shape, size, and configuration. However, it's easy to spot a catamaran by simply counting the hulls. Any sailboat with two identical hulls side-by-side is a catamaran. A sailboat with a large primary hull in a small outer hull is likely an outrigger, which is a rare type of catamaran.
Why Do Catamarans Have Multiple Hulls?
Catamarans have multiple hulls for speed and stability. The stability advantages of incorporating two narrow hulls and spacing them widely apart are easy to identify. This wide stance makes it very difficult to tip a catamaran in either direction, which increases sailing comfort and significantly reduces rolling in heavy seas.
Speed is another reason why catamarans have two hulls. Catamarans can travel at much faster speeds than monohulls because they're not bound by the rules of hull speed. When a monohull travels through the water and creates a wake, the bow and stern waves will synchronize and interfere with the speed of the boat. When these waves synchronize, the monohull has great difficulty traveling any faster.
Catamaran hulls also generate wakes, but the two side-by-side hulls effectively cancel out the synchronous interference that slows monohulls down. Additionally, the narrow design of the hulls allows them to pierce through waves instead of riding over them, which reduces travel distances and increases efficiency.
Another reason why catamarans have two hulls is that the design reduces draft. The draft is a measurement of how deep in the water the hull extends, and catamarans have some of the shallowest draft-to-length ratios in the sailboat design world. That means that a comparatively large catamaran can travel in much shallower water more safely than a monohull.
Are There Other Multihull Sailboats?
Catamarans are the most common multihull sailboat design, but there are several others available as well. The most common multihull other than the catamaran is the trimaran. As the name suggests, trimarans have three hulls instead of just two. The trimaran usually has two narrow hulls and a larger hull in the center, as the primary purpose of the outer hulls is to provide stability.
Catamarans and trimarans are known for speed. And while catamarans can double or even triple the speed of an equivalently-sized monohull, trimarans can go even faster. This is because trimarans are not bound by the rules of hull speed either, and they create less drag-inducing hydrodynamic interference than catamarans.
Catamaran vs Monohull
Catamarans have a number of distinct advantages over monohull sailboats. The most obvious benefit to experienced sailors is the increased stability of the multihull design. Picture it like a table. A table with wide legs is going to be more stable than a table with narrow legs. Leaning on it won't knock it over as easily—and the same is true out on the water.
Catamarans can also be more spacious than monohulls, without additional size in terms of length. The catamaran is a very old design, as even ancient boatbuilders knew of its advantages. However, there are some downsides to catamarans and other multihull designs, which is why monohulls are still the most common kind of sailboat on the water.
Monohulls are easy to construct. Unlike a catamaran, which must have a carefully designed load-bearing structure connecting the hulls, monohull sailboats derive all of their strength from the hull itself. In other words, there aren't as many weak points, and it's easier to build. Additionally, it's also a lot cheaper to build a monohull, in the design doesn't have to be quite as precise.
Another advantage of a monohull sailboat is that it's easy to configure the interior. If you need more space for accommodations, engineers can simply widen the hull during the design phase. Catamarans have very narrow hulls comparatively and can be hard to effectively utilize space without unnecessary redundancy or cramped quarters. Monohulls are also much more efficient for transporting cargo, as the hulls are wide enough to fit a vast amount of material.
Catamaran Hull Size
Catamarans come in all shapes and sizes. And unlike monohulls, overall length is not the primary deciding factor when it comes to performance. When you picture a catamaran, you're probably thinking about one of the large glossy cruising sailboats that often dot coastal anchorages across the world. These vessels usually range in size from 35 to 55 feet in length.
There are different types of catamarans. The most common kind, known as cruising catamarans, or usually around 45 feet in length. The smallest cruising catamaran is around 30 feet long, as catamarans don't have enough hull for comfortable accommodations at a size smaller than this. Cruising catamarans can reach astounding sizes, often exceeding 50 or 60 feet in length.
The beam, or width, of catamarans, is usually much more significant than monohulls of the same length. This is despite the fact that catamaran hulls are significantly more narrow than other types of vessels. For example, a 40-foot monohull likely has a beam between 10 and 14 feet, whereas a 40-foot catamaran can have a beam of 20 feet or more.
These factors have a positive effect on seaworthiness, as catamarans don't heel over under heavy sail and are extremely difficult to capsize. Additionally, they will float just as well upside down as they do right side up.
However, this additional beam can make docking a catamaran challenging. Marinas that can normally accommodate two large monohulls in a slip can only fit one catamaran in the same space, leading to increased mooring fees.
What Are Catamaran Hulls Made Of?
Catamaran hulls are made from all sorts of materials. The most common catamaran designs use fiberglass, which is a moldable mixture of hard glass fiber and waterproof resin. Fiberglass has been the primary recreational boat building material across the world for more than 60 years, and the technology is better than ever. Fiberglass catamaran hulls can theoretically last forever, they can be molded into any shape at the factory, and they're easy to repair.
The finest custom cruising catamarans are made from aluminum. Aluminum is an extremely costly but highly desirable catamaran building material, as it reduces weight and allows these vessels to reach extremely high speeds. Due to the cost and technical experience required to build an aluminum catamaran, the vast majority of boats are fiberglass.
Wood is occasionally used to build catamaran hulls. Today, most wooden catamarans are made from marine plywood and sheathed in a layer of fiberglass for strength and waterproofing. Traditional wooden construction is only found on outriggers, as it is costly and very time-consuming.
What Are Outriggers?
Outriggers are a type of catamaran that traces its roots all the way back to 3000 BC. An outrigger is a simple open boat with a stabilizing hull mounted off to one side. Some outriggers, especially canoes, have two stabilizing hulls.
Outriggers, while technically catamarans, are not widely used in the 21st-century due to their lack of space and one-sided stability. However, these vessels are an important part of catamaran history and a great demonstration of how multihull designs can add great stability to a boat.
