Contents of Report
Catamarans are for boaters who like a smooth ride. Let’s look at the advantages of a catamaran-style hull over a V-shaped monohull. Here we will dispel some myths and show why catamarans are becoming more and more popular.
1. Sharp Entry
When we look at a catamaran-style hull, the first thing we notice is the sharp entry at the bow, and that’s what sets them apart from a deep-V monohull, which has got a much wider entry and is not nearly as sharp. Basically, it’s like the difference between a sharp knife and a dull knife. A sharp entry on a bow cuts through the water better than a wider entry does of a monohull.
The second point to make about the catamarans are that they are a lot more stable than a monohull. If we take a V-hulled boat off the trailer and put it on the ground, it’s going to rotate on the axis of its keel and fall to one side. A catamaran, however, taken off the trailer and put on the ground, will stay at rest and be stable just as if it was in the water. For it to list, not only do we have to further submerge one hull, but we also have to lift the opposite hull. So, a catamarans tendency is to stay nice and flat, and stable at rest and at low speeds.
3. Less Drag
Once a catamaran is on plane, that’s where they really shine. There’s less drag than a monohull, therefore making them more fuel efficient. They will essentially be faster with less horsepower.
4. Plane on One Engine
The twin-engine cat will plane on one engine, but the twin-engine monohull very rarely will. With a monohull, there’s too much wetted surface, and the engine can’t overtake the drag of its big wide wetted surface.
On a catamaran, it takes a lot less power to get the boat up and over on plane. Where this is going to be important, is when you’re way offshore, and something happens to one of your outboards. You can come home at a good clip on a catamaran, where on a monohull you’re going to have to mush home at four or five knots on one engine.
5. Shallow Draft
For a V-hull to run well, it has to have a very sharp and deep entry. Well that deep entry comes at a cost; if you pull up to a sand bar, the V-hull is going to run aground much sooner and you’ll be far from the edge of the water. With a catamaran, however, there’s still the sharp entry but this time with two hulls displacing the water, so there is more buoyancy. It draws a lot less water so the boat can get a lot closer to the shoreline. It’s therefore easier to arrive in shallow water on a catamaran than on a V-hull of the same length.
6. Engine Placement
The engines are a lot further apart on a catamaran than on a V-hull of the same size. What that means, particularly at low speed docking, is an operator can spin the boat on its own axis much easier. Simply put one motor in forward, one in reverse and the boat will spin inside of its own axis much more efficiently.
7. Dive Ladder Location
One other advantage of having the engines set far apart is that you can put a larger, and therefore more comfortable, dive ladder in between. Also, the most stable place to get on board a boat is the center, so this is a convenient placement, right in the axis of where the boat is going to list. Not onto either side as on a V-Hull.
So having the ladder located right in the middle, and having the advantage of a nice big, wide ladder is another thing that sets a catamaran apart from a V-Hull of the same length.
8. A Soft, Dry Ride
When having a discussion with anyone who’s ridden in a catamaran, they’re going to rave about the soft, dry ride that these hulls have, and there’s a reason for that. On a V-Hull, the boat is displacing a lot of water, so when it hits a wave it’s going to throw all that water somewhere, and a lot of times its up in the air, and back onto the people in the boat.
In a catamaran, the boat is displacing a lot less water, and a lot of that water is getting trapped inside the tunnel. So, there’s not as much that can be thrown to the side, there’s less to go up in the air, and passengers will stay a lot drier in the boat.
The tunnel also traps a lot of air. That air that gets trapped in the tunnel creates a cushion, so that when the boat launches off a wave, before it can slam down onto the water, it’ll compress all that air inside the tunnel. That helps for a nice soft landing.
You got a sharp entry on the sponsons, and the air compressing in the tunnel. That’s why when catamarans launch off a wave and come back down, it’s a nice soft, dry landing.
9. More Forward Space
A cat has a lot more space to work with on deck, mainly because the beam on a cat carries it all the way forward. On a V-hull, the hull width is going to taper to the point of the bow. In the catamaran, the beam carries straight and forward, allowing the designers and the boatbuilders to do a lot more with that extra space. This allows for additional bow seating, additional stowage, and it actually makes the boat more stable.
A Note About Symmetrical and Asymmetrical Hulls in Catamaran Design
There are two basic designs of a catamaran; symmetrical hulls and asymmetrical hulls. In a symmetrical hull, the port side looks just like the starboard side. In an asymmetrical hull, the outboard sides are the same, but the inboard sides are straight up and down. This is typically a racing-style boat, which is used for offshore racing. They’re very fast but they’re not that good in rough water.
With a symmetrical hull, however, a little bit of speed is sacrificed, but that’s where it’ll get the smoother ride. A symmetrical catamaran rides a little bit slower but much smoother than the asymmetrical.
Displacement and Semi-Planing Hull
Now if we break down a symmetrical design, we really have two choices; a displacement hull and a semi-planing hull. With a displacement hull, the boat pretty much just slices through the water, it never really planes off, and it rides well in head sea.
It may be a little unnerving at first in a beam sea because there’s going to be some rocking that most are not used to. Once we’ve gotten used to it, it’s not too bad.
Therefore, most catamaran manufacturers now are going with the semi-planing hull. They kept the displacement in the nose, since that’s where they get the ride. But then the hull tapers and flattens out a little bit. Some even have a running pad, some have steps, but that boat actually planes. That’s where the boat is going to get the speed and better efficiency.
10. Stable Turning
One of the big myths of a catamaran is that they can’t make sharp turns. Well that’s just not true. A catamaran can indeed make a sharp turn, and even get the boat to lean into the turn much like a V-Hull.
On a slower turn, the boat really likes to lean in, on a faster turn it’s going to stay a little flatter. This is something to get used to, but it’s still very stable and not unsafe.
So, these are some of the top advantages of a catamaran hull. We certainly encourage a test ride when considering a purchase, and more often than not, that will be the selling point once the sales rep has driven home the advantages of the space and roominess that only a cat can present.