CAT vs. MONO The 10 questions that ignite the comparison between catamarans and monohulls

The comparison between catamarans and monohulls has always fascinated sailing enthusiasts. Much has been written, the differences in sailing and life aboard are as innumerable as are the tastes of sailors and the needs of owners. Without, therefore, falling into the temptation of pronouncing judgments, we have collected ten recurring questions in the debate between catamaranists and monohullers, and sought answers by looking at the reality of recreational cruising. The market for multihulls is continually expanding, with more and more of them being seen both in the dream destinations offered by charters and in many equipped ports in the Mediterranean. As you read this article, you will understand why and dispel some myths.

CATAMARANS VS. MONOHULLS

1. Is it true that the catamaran can capsize because it does not have a bulb?

Yes, but catamarans are as safe as monohulls. it has happened, in extreme sea and wind conditions, that some older generation cats have scuffed, but we are talking about conditions in which, any boat, even a monohull, would be in distress. it is also true that, some monohulls, although not in distress, have lost the bulb. Safety is an issue heard in mono- and multihull comparisons, but it cannot be trivialized to the probability of capsizing. All safe boating conditions are evaluated by the designers and certified by the relevant bodies so the boater need not worry. If we really want to see extreme cases, it is true, in case of a capsize the catamaran will not come back straight, but it is also true that it will be a kind of huge floating raft, practically unsinkable, because of the redundant hulls.

2. Is it true that the catamaran never heels?

Let’s say yes. The major difference in sailing a catamaran compared to a monohull is the reduced heeling even in upwind gaits. A modern cruising catamaran, it does not tilt more than 10 degrees, and when these angles are reached, it is time to reef the mainsail and roll the jib.
It is one of the main reasons why the catamaran is valued for cruising and vacationing by those who are not accustomed to moving around on board and would find it difficult to accept long sailings with the need to hold on to handrails or toeboards. The skipper accustomed to monohulls often has to get used to this lack of heel, the first feedback of wind power on the mainsail. It is a different matter for trimarans, which do indeed tilt. For example, the maximum heeling angle of a Neel is as much as 27 degrees, this allows for higher performance and greater tolerance to gusts with wide margin tilt, before having to reduce the sail.

3. Is it true that the cat goes faster in the slack, and in the stern?

Yes. Catamarans on the slack are much faster, and they achieve considerable speeds even without the aid of gennakers. The drag, because of the tapered shape of the hulls is less, and not having the bulb and tons of lead ballast, the sail area-to-weight ratio is more advantageous.
However, distinctions must be made; catamarans primarily oriented toward comfort or cruising do not reach speeds that much higher than those of a good monohull, due to the static weight of the superstructures and the slightly reduced sail, while more performance-oriented catamaran designs, see for example the Italian Ice Cat 61, the French Outremer 45 or Excess 15, or catamarans from the Privilège shipyard such as the Signature 580, reach speeds almost twice as fast as good performance monohulls.

4. Is it true that the cat struggles upwind?

No, not anymore. The early catamaran designs were indeed very underperforming upwind, and in spite of themselves, they were being compared with monohulls that had been accruing excellent performance in upwind for decades.
Things have changed. Catamarans now ascend the wind at slightly greater angles than in the past and, above all, at much higher speeds: this, at the VMG level, makes them equal if not better than monohulls. Design technology and new materials have made it possible to design hulls that minimize not only drift, a real problem in the absence of a fin, but also the mutual turbulence effects of the two hulls.
Given the speed, the apparent wind is higher so the sails become more efficient in poor winds.
The large superstructures of catamarans expose a lot of surface area to the wind, but the window deck shapes are all designed with areodynamic criteria in mind, and no longer generate severe turbulence on the sails as they once did.

5. Is it true that less horsepower is needed for the catamaran engine?

No. For the same displacement, assuming equal hydrodynamic performance, the thrust required to accelerate the same mass, whether a catamaran or a monohull, is equal. This is easily verified: for example, the Lagoon 450 displaces 15t, has 90 horsepower spread over two 45hp engines. A 14t SunOdyssey 519, mounts an 80hp engine.
Having two thermal engines is an advantage for redundancy in case of failure, but an energy handicap: the single diesel engine in the monohull is more efficient than two small ones with the same total horsepower. To overcome even this limitation, ItaCatamarans has offered its new 14.99 with electric propulsion through a partnership with OceanVolt. Since electric motors are much more efficient, the thermal energy loss of a second motor becomes negligible.

6. Is it true that the catamaran offers greater comfort?

Yes. Increased comfort is one of the key reasons for the success of modern catamarans in the cruising charter world.
The generous space on board also makes even tourists new to sailing comfortable, who increasingly rely on charters that have catamarans in their fleet.
It is precisely the arrangement of volumes that makes, even with the same square footage, habitable space more usable than monohulls. Living spaces are flat and in a higher position on the sea, offering more light, ventilation, visibility, never a sense of claustrophobia. The ceilings are high and you don’t have to crouch.
The cabins divided into two hulls offer more privacy and separation from the living area; you move around on board almost as if you were on land. Windows, sofas, coffee tables, chairs, kitchen and bathroom, and appliances are similar to those of a nice seaside apartment.
Catamarans from shipyards such as Fountaine Pajot and Nautitech, Bali or Sunreef, featured in our list, are designed with a strong focus on comfort on board.

7. Is it true that cat mooring costs more?

Yes unfortunately, because for the same length a catamaran takes up twice or three times as much dock space.
Not only mooring, but also many services at the marina or boatyard can come at double the cost because of the space occupied by multihulls, or towage cranes large enough for hoisting may not be available.
This is the real reason for the low uptake of catamarans today in Mediterranean ports, which tend to be smaller, with few marinas equipped to accommodate large catamarans. Although we are beginning to see ports in Italy offering favorable rates to catamaran owners, who go as far as paying as if they had a monohull berth.

8. Is it true that the maximum draught is five feet?

Yes. Most catamarans in the 40-foot range do not dive more than five feet. Some catamarans are equipped with two tilting fins, which can have a considerable draft when fins are down, take for example the Catana 53, which goes to 3.60 m, even greater than the draft of an Allure 51.9 or the Ovni 495, well-known monohulls with retractable fins.
Cats are the preferred boats for cruising on coral reefs because of their shallow draft and ability to beach.
Not only Belize, the Bahamas, Polynesia, or the Great Barrier Reef are more easily explored: in shallow water, so many of the jobs at the live opus that would require a diver on a monohull become easier.

9. Is it true that it is more difficult to sail the catamaran than monohull?

No. Many novice skippers find the catamaran easier and quieter to pilot for several reasons. The dashboard is located on the catamarans in prime visibility positions, you have everything under control, and you are always dry.
The reduced skidding does not require athletic skills for any crew member, which also makes maneuvering easier. Once put with the bow to the wind, the catamaran does not lower the bow like a monohull, it does not tend to lean, it generally backs off with the bows to the wind.
This property also makes taking a buoy under sail a relatively simple maneuver: you can aim for the buoy and pass it by letting it spin under the trampoline, with good margin to stop, and then let it bob in reverse for recovery.
In tacking, one can lose speed more easily and fail to change tack, but this is not seen as a problem for beginners; on the contrary, slow tacking is considered easier, and in case of stalling, it is resolved with a neck jib, or a motor stroke on the upwind hull.
Where you need to be more experienced is in catamaran handling in rough seas, but this is true on monohulls as well. The rudder provides minimal feedback to the wave and the whole boat has a different response, but it is just a matter of habit.

10. Is it more difficult to maneuver in port by motor?

Yes and No. The larger size, especially in some space-constrained marinas, can be a problem in traffic conditions: drift in windy conditions, either on catamarans without fins, or even more so with liftable fins raised, is much greater than on the monohull. But in confined spaces, thanks to the two engines, the catamaran maneuvers with an ease that makes even bow-thruster-equipped monohulls envious. On the monohull, it is necessary to master motor, rudder, propeller evolutionary effect and bow thruster effect.
On a catamaran, one can forget even about the rudder and simply maneuver with one hand on the levers of the two motors, playing only with forward and reverse gears.
Upwind, motor-driven, the cat suffers more from waves and will expose more surface area to the wind, will therefore struggle more. The catamaran can maneuver in harbor excellently by taking advantage of its two engines, and because of the lack of ballast, the feeling of those at the helm is that, for the same boat length, the catamaran is far more responsive by motor, and has no momentum–but we are misled by the size, what matters for the motor is displacement.

Luigi Gallerani

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