is a catamaran a ship

What Is A Catamaran Sailboat? (And What It Looks Like)

What Is A Catamaran Boat? (And What It Looks Like) | Life of Sailing

Catamarans are increasingly popular for sailing and commercial use, but what sets them apart from monohulls and other multihulls?

A catamaran is a twin-hull boat with two equally-sized hulls placed side by side. They’re powered by engines, sails, or both—and they’re known for efficiency and speed. Catamarans are the most common kind of multihull boat.

In this article, we’ll go over the characteristics of catamarans and how to differentiate them from other types of boats. Additionally, we’ll cover the advantages and disadvantages of catamarans and compare them to trimarans and monohulls. We’ll also go over the most common types of catamarans and their uses.

We sourced the information in this article from marine design guides, boat identification resources, and the online boating community.

Table of contents

‍ How to Spot a Catamaran

Spotting a catamaran is easy. Simply look at the hulls and count them. Catamarans have two hulls side by side and a relatively large gap between them where you can see light on the other end. Catamarans are distinct from trimarans, which have an additional hull between the two outer hulls.

How do Catamarans Work?

The principle behind the catamaran is simple. You can think of catamarans like cars and monohulls like motorcycles. Catamarans distribute their weight between hulls on either side, whereas monohulls utilize only one hull.

Evidently, cars are much more difficult to tip over and can hold much more weight. Additionally, cars are wider, as they have much more contact with the road. Catamarans work in a similar way, as they have a wide stance and contact with the surface on both sides.

Obviously, that isn’t the most precise comparison. But the basic principle is the same, and catamarans have a few notable benefits over monohulls.

Catamaran Vs Monohull

Catamarans are easy to distinguish from monohulls. A monohull is just a regular old boat with a single hull. The vast majority of boats and ships are monohulls. Catamarans have two hulls, which are usually sleek and narrow.

Here are some comparisons of catamarans and monohulls, along with the advantages twin-hull designs have over most single hull types.

Benefits of Catamarans

Catamarans have numerous benefits. The first is speed. Catamarans produce less drag than monohulls and thus can achieve excessive speeds both under sail and power. They don’t need to plane like monohulls to achieve these high speeds, and they use less fuel.

Catamarans are also much more stable than monohulls. They have a wide stance and shallow draft, and many waves and swells can travel between the hulls instead of below them. This effectively reduces an entire axis of movement and prevents catamarans from rolling excessively.

Drawbacks of Catamarans

Catamarans aren’t advantageous in every way, or else we wouldn’t bother building monohulls. The disadvantages of catamarans limit their use to niche commercial applications and high-end yachts. But what are the drawbacks of a twin-hull design?

Sailing catamarans don’t follow many of the traditional boat handling rules and characteristics that sailors pass down for generations. Some, such as hull speed limitations, are good to do away with—while others, such as responsiveness, are not.

Catamarans aren’t as quick to the helm or responsive as monohulls. There are some exceptions to this rule, but for the most part, you’ll get a lot more feedback from a single-hull vessel. Additionally, the large section of deck between the hulls of a catamaran is prone to pounding in rough seas, which is loud and uncomfortable.

Catamarans can sometimes be twice the width of an equivalent monohull sailboat, which can increase mooring fees and limit docking options.

The final major drawback of catamarans is a consequence of their stability. Traditional full-keel monohull sailboats have a very low center of gravity, which makes them roll in heavy seas but ensures a recovery.

Catamarans have a higher center of gravity, and they can’t right themselves after a knockdown. And though catamarans are less likely to roll, a severe list on a multihull is a much more serious concern than on a ballasted monohull.

Catamaran Vs Trimaran

Catamarans and trimarans are often lumped together, but they have very different design and performance specifications. Trimarans have three hulls, whereas catamarans have two.

Trimarans look a lot like catamarans from the side, but a quick glance at the bow or stern can set them apart. Trimarans are faster than catamarans, as they distribute their weight across three hulls instead of two. This helps them stay centered and reduces interference from pitching and rolling.

Catamarans are fast, but they lose out to trimarans when going head to head. However, catamarans are much less expensive to build and maintain and often have roomier cabins due to their larger hulls.

Types of Catamarans

There are numerous types of catamarans, and their uses vary widely. The catamaran is one of the oldest and most useful hull types, and some variants have been used for thousands of years. Here are the most common kinds of catamaran boats and their uses.

Sailing Catamaran

Sailing catamarans are probably what you think of when you hear the name. Sailing catamarans are sailboats with two identical hulls connected by a center deck. The largest sailing catamarans are spacious and stable vessels that are capable of serious offshore sailing.

Sailing catamarans have a number of notable advantages over monohulls. Monohulls, which are traditional sailboats with a single hull, are limited by a simple concept called hull speed. As the bow and stern wave of a monohull intersect, they cause drag which limits the top speed of the boat.

Catamarans are not bound by hull speed limitations, as they have two hulls. Catamarans can go twice or even three times as fast as similar monohulls and achieve excellent travel times.

Catamarans are also more stable than monohulls, as their wide stance and shallow draft reduce the effect of rough water. They don’t heel, as the force of the wind is counteracted by the double hulls. Additionally, modern sailing catamarans can ‘wave pierce’ by cutting through swells instead of riding over them.

Sailing catamarans come in many shapes and sizes. Small sailing catamarans, such as those used in races and regattas, are known for their speed and relative stability compared to light racing monohulls. Sometimes, they feature a smaller second hull for stability—these are called outriggers.

Sailing catamarans have spacious interiors thanks to the large cockpit between the hulls. This cockpit usually contains cooking and eating spaces, a place to sit, and a hallway between the hulls. The hulls usually contain living quarters and often mirror each other.

Power Catamarans

Power catamarans have an even greater variety than sailing catamarans. These vessels are used for everything from party platforms to ferries and patrol boats.

Power catamarans are a recent development, as engineers and marine architects now realize they have numerous hydrodynamic advantages over other hull types.

Catamarans are much more efficient than other hull types, as they have less drag relative to their size. Additionally, you can build a much larger catamaran with less material. This makes them popular for car and rail ferries, as builders can construct a very wide vessel with two small hulls rather than a narrower vessel with a large single hull.

Military and Commercial Catamarans

Even the military has found a use for the catamaran hull shape. The Spearhead class EPF is an expeditionary fast transport vessel designed for carrying capacity and speed. It has two sharp hulls and a huge cargo capacity.

The Spearhead class EPF is 337 feet long, which is about the same length as a WW2 escort destroyer. Yet despite having a similar length and displacement, these catamarans can travel more than twice as fast—43 knots, or nearly 50 miles per hour. Their great speed is a direct consequence of their catamaran hull type.

Power catamarans are also used as patrol and utility boats on a much smaller scale, with either outboard or inboard motors. The State of Texas uses catamarans to patrol shallow rivers and lakes. Texas Game Wardens utilize state-of-the-art aluminum catamaran patrol boats, which are fast enough to outrun most fishing boats.

There’s another form of power catamaran that you may not have considered. Pontoon boats are technically catamarans, and they’re enormously popular on lakes and rivers throughout the country. Pontoon boats aren’t known for speed, but they’re a great platform for a fun and comfortable outing.

Catamaran Houseboats

The final common type of power catamaran is the two-hulled houseboat. Houseboats don’t always use the catamaran hull type, but it’s common enough that most major manufacturers offer it as an option.

Catamaran houseboats have a few notable advantages over monohull designs. For one, they’re easier to build—especially when pontoons are chosen. Additionally, they’re better suited for navigating shallow water. These vessels can support more weight across their two hulls, offer increased stability, and they’re also efficient.

Why Aren’t Catamarans More Common?

With all the advantages listed in this article to consider, it may seem strange that the use of catamarans is still somewhat limited. At the end of the day, it comes down to economics—as monohull boats and ships are simply cheaper to build.

Additionally, catamarans have some distinct limitations. Monohulls have lots of storage space in their hulls and can carry thousands of tons of cargo safely in all weather conditions. Catamarans lack this space and low center of gravity, so they’re not ideal for transporting cargo past a certain point.

Additionally, monohulls work, and many people are reluctant to experiment with new designs when old designs work just fine. This rule applies to both large and small boats.

A large monohull sailboat can be constructed at low cost from stock plans and reliably sail almost anywhere. Very little complex structural engineering is involved, and looser tolerances reduce cost and maintenance requirements.

Daniel Wade

I've personally had thousands of questions about sailing and sailboats over the years. As I learn and experience sailing, and the community, I share the answers that work and make sense to me, here on Life of Sailing.

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What Is a Catamaran? Things You Need to Know

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Whether you’re a sailing enthusiast or have recently adopted an interest in yachts, you’ve probably heard of catamarans. It can be confusing as the term seems to describe boats, ships, and even massive-cruise vessels. So, what is a catamaran?

A catamaran is a boat with two hulls and a bridge between them. Catamarans can be designed as sailboats or motorboats. A catamaran stays stable since it has a wide base, it does not have a deep keel as on a monohull . Cats are known for not heeling, increased comfort, more space, and faster speeds.

In this article, we will explore everything you need to know about this design, including its origin and its advantages.

Table of Contents

Catamaran: A Basic Overview

The term catamaran comes from a 17th-century Tamil term kaṭṭumaram . The Tamil word stands for “tied wood,” but those vessels do not share the same working principle as catamarans.

Even though most “tied wood” rafts in the 17th century India used two logs to keep the deck afloat, the logs acted more like pontoons than catamaran hulls. However, the commonality of two logs translated to catamarans, as these vessels generally have two hulls.

Since the term refers to the design, it is correct to refer to any vessel with two hulls connected by a bridge as a catamaran. However, technical accuracy doesn’t necessarily mean general-use correctness. While cruise ships can have catamaran design and small rafts may feature two hulls, the term is most often used for yacht-sized cruising sailboats.

Buyers who would not previously afford any vessel close to a mid-sized yacht can easily order a brand-new catamaran. Even investors interested in collecting income from catamaran renting opt for medium scale catamarans to hedge against depreciation and damage. Therefore, the term catamaran has become synonymous with medium-scale yachts with two hulls.

For the rest of this article, we’ll use the term to reflect these vessels, and if a catamaran-style cruise-ship or smaller boats are brought up, the distinction will be highlighted. It is also worth noting that even when dealing with manufacturers and industry literature, the word will refer to medium-sized yachts unless specifically differentiated.

What Are Catamarans Made Of?

One of the most interesting subjects in the overall catamaran conversation is the materials used to manufacture these vessels. That’s because different brands use different technology to compose the materials required for the hulls and other areas of a catamaran.

Hulls of a Bali catamaran are built with sandwich infusion technology using polyester and closed-cell PVC. The brand’s catamarans are fitted with daggerboards, and material variety includes Kevlar in regions of impact and carbon fiber in the lower-weight areas.

Lagoon catamarans have a history of using solid glass below water level , but newer models have a balsa core in the submerged region . While the specifics of composting technology and materials may vary from brand to brand or even model to model within the same brand, the fact that most of these vessels are made of composite material remains consistent.

Parts of a Catamaran

One cannot ask what a catamaran is without getting curious about the various parts of such a vessel. Here is a breakdown of the various parts that go into this vell’s construction:

Unlike monohulls, a catamaran has two of these. They’re usually hollow and fitted out with beds and even a glass window to look out into the water since they’re not submerged. The hulls’ function is to push down on the water, so the water reacts by pushing the vessel up. Therefore, they play an essential role in the catamaran’s buoyancy.

Cross Beams

Because the hulls exert force on the water, there needs to be something that ensures the water’s reaction (upwards force) doesn’t break the deck. Crossbeams serve as connectors between the two hulls and hold them together such that water’s upward force is distributed evenly across the surface between the hulls.

Depending on the size of the vessel, the number of cross beams may vary. Some of the critical characteristics of cross beams include high density and low surface area.

A bridgedeck, as the name suggests, is a deck that serves as a bridge between the hulls. Manufacturers make a compromise between space and sailing efficiency when deciding how to design a bridgedeck for their catamarans. A bridgedeck is given significant clearance to allow for smooth sailing but not too much to leave behind, only the deck for living space.

What you should keep in mind about a bridgedeck is that the smaller its clearance, the more water hits its bottom, causing discomfort for those sailing and dealing damage to the vessel. Also, you can’t minimize the bridgedeck without affecting the hull size, which means you have to compromise between the two.

Bridge deck slamming explained

Other Parts

While the aforementioned parts are key to a catamaran’s construction, they are by no means an exhaustive list of every vessel’s component.

Catamarans have a topdeck, oftentimes a saloon, and separate chambers depending on the size. The standard vessel will have the interior fitting of a yacht of a similar size. Since none of these parts are specific to catamarans, a detailed breakdown of each isn’t necessary.

Catamaran parts explained

How Long Does a Catamaran Last?

Since catamarans aren’t impulse-buys, you must consider the longevity of the specific model you wish to buy. If you go with a boutique manufacturer without knowing about materials and construction, you may be sold a vessel that may last only seven years.

On the other hand, brands that list their construction methods with transparency regarding materials used are more confident in their product, which has five times the longevity of a cheaply manufactured catamaran.

Suppose you wish to purchase a catamaran you want to have for 15+ years. In that case, you may avoid buying a “performance” catamaran that focuses on lightweight in favor of sailing speed and effortlessness on the waves. This conversation becomes more complicated when you consider sailing frequency and its impact on different vessels.

Generally speaking, expecting your catamaran to remain functional and smooth sailing for fifteen years is reasonable. That doesn’t mean any catamaran you purchase will fit this criterion but only suggests that you will find vessels with this longevity with relative ease.

Is It Easier to Sail a Catamaran?

It is essential to address different sizes of catamarans when this question arises. Sailing a catamaran sailboat is different from captaining a standard (yacht-sized) catamaran. Since yacht-sized catamarans can come with an autopilot, as can their monohull equivalents, the question becomes more about the sailing experience.

Your guests are more comfortable in a catamaran as the sailing experience doesn’t translate water resistance and wind to the vessel’s interior as much as it does in a monohull. Monohulls get hit by waves that pass between the two hulls of a catamaran.

As for physically sailing a catamaran-design vessel, the experience is different but not objectively easier. For instance, if you’re a seasoned monohull sailor, you’ll find what you’re used to much easier than adjusting two catamarans.

Final Thoughts

Catamarans are self-balancing and easy to learn, making them a preferred sailing choice among novices and time-strapped sailing enthusiasts. They have recently become symbols of luxury with comfortable interiors and ample living space.

Owner of CatamaranFreedom.com. A minimalist that has lived in a caravan in Sweden, 35ft Monohull in the Bahamas, and right now in his self-built Van. He just started the next adventure, to circumnavigate the world on a Catamaran!