What Are the Characteristics of a Catamaran Hull

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This article aims to give you more insight on what are the characteristics of a catamaran hull and whether you should consider it for your next boat.

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What is a Catamaran?

A catamaran is a double parallel hull sailboat – a geometrically sound watercraft using a wide beam for stability, instead of a ballasted keel like the mono hull boat. The catamaran has smaller displacement, shallow draft and less hull volume compared to mono hull boats.

The double hull is the distinct feature of a catamaran, making it immediately recognizable. Its versatility, sleek style, comfort, and speed are features that make people often compare it to a yacht.

South Pacific islanders invented the twin-hull, but the design was first seen in India during the late 17th century. The catamaran was not known in the west until 1877 after American Nathanael Herreshoff started developing racing catamarans. 

Herreshoff’s design was faster than the mono hull design. This prompted sailing authorities to ban catamarans from joining sailing competitions for almost a century.

Today, catamaran designs are categorized under two major types, the traditional racing catamarans, and the cruise catamarans.

Deck Surface

One of the advantages of using a catamaran is its wide deck space. The two hulls are connected to a crossbeam, giving space for a stateroom below and a bridge deck and deckhouse above. You can use the two hulls to build two staterooms with their own private head. It can serve as a lounge or resting/sleeping room. 

Above the hull where the crossbeams connect, you can build a deckhouse and bridge deck that you can use as a galley, a minibar or where you can simply sunbathe – perfect for an idyllic vacation with family or with your significant other.

Catamaran Hull Speed

Let’s not drive ourselves crazy over using the formula to calculate hull speed. Let’s leave that to the design engineers and manufacturers. We will make it simpler by determining speed knots, which is familiar to everyone.

The racing catamaran runs at a speed of 30 to 40 knots. The cruising catamaran run at a speed of 9 to 15 knots depending on its weight. The heavier it is, the less speed it runs.

Seaworthiness and Hull Performance

Seaworthiness means your boat’s ability to provide comfort and safety to you and your crew in any weather condition. Seaworthiness of your hulls’ performance is affected by many factors such as stability, windward ability, resistance, weight, and wave motion. Note that the hull performance of a catamaran greatly differs from a monohull sailboat.

Stability

The catamaran relies on hull stability to avoid capsizing and heeling, and hull stability relies on the buoyancy and beam of the boat. A standard beam length of a cruising catamaran is about 50% of its size. Say, if your catamaran were 50 feet long, the beam would be about 25 feet wide to keep the balance between the heeling and righting moment.

Resistance

The twin hulls of the catamaran work together to develop a smaller hydrodynamic resistance, allowing the catamaran to require less propulsive power from either engine or sails. 

The catamaran hulls reduce heeling and wave-induced motion that helps diminish waves, giving passengers a more comfortable ride. The catamaran has lower resistance when ploughing through water.

Weight Carrying Ability

The more overloaded the catamaran is, the more its performance is reduced, which could eventually lead to safety issues. Check if the hull has interiors and cored construction made from light materials.

Catamarans accelerate when they encounter wind gust so they need to be strong. Cored construction makes the catamaran strong and hard. The twin hulls are normally at odds with each other, trying to find their own direction and the structural design of your catamaran should be strong enough to handle this, plus the down force of the mast.

Ease of Handling

The deck layout helps a lot in the ease of maneuvering and docking a catamaran. Most catamarans do not have too many deck hands. There should be one focal point where everything connects, and in this case, it is the helm. From the helm, ensure you have visibility of the bows and pulpits, the sterns, and the crossbeams handling the anchors. This will help you avoid blind spots and possible accidents.

Bridgedeck Clearance

One crucial point in a catamaran’s seaworthiness is bridgedeck clearance; this is the distance between the water and the bridgedeck. The bridgedeck clearance gives ocean waves headroom to pass in between hulls. Another reason is each bow in your catamaran creates bow waves that meet under the bridgedeck, thus increasing the need for a higher clearance.

So what if it creates bow waves? It will still pass through, right? Yes, it will, but without enough clearance, it will cause pounding on your catamaran. When the waves slap or pound against your catamaran, it can greatly reduce your speed by 3 to 4 knots; it can also cause physical discomfort to your passengers; and lastly, it can cause excessive harm on your boat and rig.

Windward Ability

Majority think that catamarans cannot point as high as the mono hulls into the wind. However, some modern catamarans can point just as high as mono hulls even in stronger winds. 

The problem is not how high the boat points are but rather on the leeway the catamaran makes. A regular cruising catamaran has keels, while the high performance ones have dagger boards. The ones with dagger boards can point much better than the cats with keels. Many believe that keels trip the boat as it navigates down while dagger boards gets sideway on waves.

Takeaway

The catamaran has grown in popularity over the years for good reason. It’s not important which hull type you choose whether is multihull or monohull because at the end of the day you will all enjoy the same sunset and same ocean. Thank you for reading this article about what are the characteristics of a catamaran hull.

Happy Sailing!

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