Do you love the natural sounds of water sliding past the boat’s hull and a breeze blowing across your rigging and sails while gliding ahead powered only by the force of the wind? If yes, you are well-suited to spending plenty of time on a sailboat, like so many generations of boat people before you.
But do you take your lead from the Egyptians who rigged sails on their boats built of reeds along the Nile River or follow the path of the Polynesians, who used an outrigger for extra stability and sailed from one Pacific island to the next in the earliest catamarans?
The question of which is better for sailing, one hull or two, has been a matter of debate over thousands of years. Today, let’s explore these two basic types of sailboat, and while we may not settle the argument once and for all, hopefully in the process you will begin to discover which option is better for you.
What Are the Differences Between Catamaran and Monohull Boats?
The monohull and the catamaran (often referred to as “cat”) are the two most common categories of sailboats, and of the two, the monohull far outnumbers the catamaran in popularity due to its simplicity and sturdiness. Advocates of the catamaran, however, are typically even more convinced than monohull sailors that their boats are best due to performance potential and overall spaciousness.
What are catamaran-style boats?
Catamarans are easily identified by their two-hull design. Two hulls sit side by side with an interconnecting deck or structural beams across the bap in the middle. Catamarans have been around since Pacific Islanders and other Austronesian people sailed them centuries ago, and they continue to gain popularity in a wide range of designs both as high-performance racing boats and ocean-cruising designs.
Although not part of this debate, a third sailboat type comparable to a catamaran is a trimaran. Trimaran sailboats are constructed similarly to catamarans but have three parallel hulls rather than two. Collectively, catamarans and trimarans are referred to as multihulls, and sailors of both types often refer lightheartedly to monohulls as “monomarans.”
What are monohull-style boats?
Monohull sailboats are the most common boat type because they feature a single hull, typically with a single mast and two sails. Rather than maintaining stability with a second hull creating a wider beam, monohull boats usually carry lead or other heavy ballast in their keel, or are stabilized by human weight as their crews lean out to counter the force of the wind. Monohulls can also be excellent racers and cruisers, depending on their size, volume, sail area, and displacement or weight.
Where Catamarans and Monohulls Excel
Each type of boat has its advantages, depending on what the owner wants in a boat. Here are the main advantages of each type.
• More space. Catamarans have greater beam for a given length, which provides more space for the crew on a daysailer and larger living quarters on cruising designs, which are often laid out with berths in each hull and living quarters across the bridgedeck between hulls.
• Faster hull. If they are light enough, the sleeker shape and reduced wetted surface of two narrow, shallow hulls can produce quicker straight-line sailing speed than a single, deeper and wider hull.
• Comfort and stability. Two hulls provide better initial stability and generally heel less than monohulls, especially in light- or medium-strength winds and waves.
• Upwind sailing. When sailing against the wind, monohulls often sail at a closer angle to the wind and arrive more quickly at their destination.
• Easier motion. Heavier monohulls often have a slower, gentler motion in waves than a lighter catamaran.
• Load carrying capability. A monohull’s performance is reduced less than a catamaran’s when the boat is loaded heavily with cargo or crew.
• Righting characteristics. Larger monohulls have weighted keels that provide increased resistance to a capsize when the boat is heeled far over by wind or a wave and if capsized will return the boat to an upright position.
Catamaran vs. Monohull Sailing Speed
There are several reasons why a catamaran is often faster than a monohull boat. These include the fact that most catamaran hulls have less water resistance than monohulls, they are often lighter, and they can be more easily driven by a relatively small sailplan. At similar lengths, a catamaran can be dramatically faster than a monohull under similar sea conditions. However, weight is the enemy of a catamaran’s speed; a heavy or heavily loaded catamaran may be much slower than a lightweight monohull.
Catamaran vs. monohull power
A monohull under auxiliary power may be faster than a catamaran in certain conditions, like powering against a strong wind. In other wind and wave conditions, the catamaran is often faster. Also, with an engines on each hull, the cat is often much more maneuverable in close quarters or at the marina. While it may seem counter-intuitive, turning and controlling the boat is often less challenging than when sailing a monohull boat with the typical single engine. Monohull boats require more finesse when in tight quarters like berthing in a marina.
Catamaran vs. Monohull Efficiency
A sleek monohull may sail against the wind super efficiently, pointing close to the wind and making an excellent speed. However, the power-to-weight ratio of the catamaran allows it to make good use of whatever wind it has. Some fast, light catamarans can travel at speeds equal to or faster than the wind, something very few monohulls can achieve. When the wave action increases and you start sailing into the wind, the catamaran may lose its advantage, and in strong winds, the greater windage of the wide catamaran may have a pronounced slow-down effect compared to the sleeker monohull.
Catamaran vs. Monohull Stability
Despite not having a weighted keel, a catamaran design is able to avoid heeling over in strong winds or bad weather due to its greater width or beam. As a result, the multihull also tends to be more stable at anchor and any time in calmer seas. However, if the winds are strong and the waves are large, a monohull, with its keel weight and ability to sail against the wind while controlling the sails, is sometimes the steadier of the two types. While a monohull with weighted keel can be knocked down by strong gusts of wind, it will only capsize in extremely large waves. Likewise, a cruising catamaran can only capsize in large ocean waves, unless it is a fast, lightweight catamaran, that can more easily tip over in gusty winds and waves.
Catamaran vs. Monohull Safety
Power catamarans and power monohulls are relatively comparable in terms of safety. But depending on the size of the mast and sails, the weight of the boat, and the wind and wave conditions experienced, many sailors believe that a monohull configuration is safer than a catamaran for a sailboat. That’s mainly because while a monohull will initially heel over further in a strong gust of wind, the weight of its keel provides increasing stability as described above and if completely capsized, the keel typically helps the boat self rescue.
It should be clarified that many sailing catamaran designs are conservatively configured and difficult to capsize except in extreme ocean wave conditions—and the same can be said for larger power catamarans.
In terms of ultimate safety in the event of a capsize, however, the catamaran is considered safer because even should it turn once upside down, even if damaged, the catamaran with its two hulls and minimal ballast typically remains buoyant and provides a safer configuration in which to await rescue. By contrast, if a monohull’s hatches and port windows suffer damage in a knockdown, the boat can more quickly take on water and, weighed down by its keel or other ballast, be more difficult to keep afloat in extreme conditions.
Photo credit: Fountaine Pajot
Monohull vs. Catamaran Maintenance
Depending on size, age, and type of hull construction, maintenance costs will vary, but when comparing two fiberglass sailboats of similar length, the catamaran typically costs more to maintain. That’s because there are two hulls to care for, two engines, connecting structures that align the two hulls, and an overall larger boat due to the catamaran’s greater beam. Hauling and launching a catamaran can be more expensive at many boatyards, as well.
However, smaller catamarans of about 20 feet in length or less are often more comparable and sometimes cheaper to maintain than a similar length monohull. That’s because cats are often lighter and suitable for keeping on a trailer rather than in a slip or on a mooring.
Catamaran vs. Monohull Cost
Compared to similar length monohulls, a catamaran will likely cost more than a monohull boat. That’s mainly because when you purchase a 40-foot catamaran, you are buying two hulls and two engines, but you are also buying a bigger boat that typically has much more volume. In the case of a 40-footer, you end up with a boat that has a large saloon and three or four private cabins, whereas in the monohull, the saloon is smaller and you’ll have three smaller sleeping cabins. Annual maintenance will also be greater, as described above.
Among smaller catamarans and monohulls, pricing will vary, and a lightweight beach cat may be less expensive than a heavier monohull keelboat of similar length.
Catamaran vs. Monohull, Pros and Cons
Depending on a variety of factors, there are plenty of catamaran and monohull pros and cons. These are some to keep in mind when comparing the two boat types.
• Comfort. On a cruising designed catamaran, two hulls with a wide beam create a stable and comfortable living environment with open spaces and plenty of standing room.
• Speed. Smaller, lighter catamarans are speed champions, especially in a moderate wind and modest waves. Cruising cats are often fast when sailing at reaching angles.
• Maneuverability. When equipped with two engines, a catamaran is highly maneuverable under power.
• Upwind sailing. Although catamarans are often faster when sailing in a straight line, monohulls typically perform better against the wind.
• Self-righting. Except for unballasted monohulls that rely on crew weight for stability, the ballasted keel of a monohull prevents capsizing in most circumstances and the keel makes the boat self-righting.
• Maneuvering under sail. Monohulls turn more easily due to their shape, maneuvering in close quarters or tacking when sailing against the wind.
• Lack of feel when steering. Except in lighter, more performance-oriented catamarans, the broad platform with two rudders and two hulls sometimes isolates the sailor and provides little feedback through the helm when under sail.
• Sailing against the wind. Upwind sailing is generally not a catamaran’s best point of sail, but its straight-line speed can be such that it may arrive quickly at its destination, even though you will have traveled much farther than in a monohull.
• Pricing. Catamarans are typically more expensive than monohull boats due to their two hulls and other required build components and complexity.
• Not self-righting. Thanks to its wide beam and two-hull design, a catamaran is more difficult to flip, but it is not designed to right itself except for small beach cats where the crew can use their weight to re-right the boat.
• Weight. Most monohulls have thousands of pounds of weight in the keel for ballast that is vital to its stability but can degrade performance.
• Wave motions. Monohull boats are much more susceptible to rolling wave motions.
• Cabin. With the monohull cruising design, you'll typically find a darker interior with smaller port windows and fewer space options.
• Heeling effect. Monohulls will heel over in a moderate wind, which is normal but often uncomfortable for newer sailors.
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