Sailing Performance and Safety
While most traditional boats over 20 feet are monohulled keelboats, there are major limitations to the type of sailing you can do with a monohull. First of all, monohulls depend on their keel to keep them upright, which is effective, but the force of the wind almost always causes the boat to heel to leeward by angles of up to 25° under reasonable cruising conditions, which can be quite uncomfortable for the crew! This design, which relies on giant lead ballast in a deep-set keel, is vulnerable to capsizes and, in drastic cases, sinking.
Additionally, the single-hull only provides so much volume for accommodation and storage, while the more horizontal layout of the multi-hulls can increase cockpit and cabin sizes substantially. Beyond that, both types of multi-hull can experience higher speeds at a given hull length than monohulls.
So how do cats and tris compare to each other? Well,
Catamarans: Stability and Ease
With their dual ‘pontoons,’ Catamarans make use of their floats to always remain on a flat and consistent angle of heel, rarely sailing under more than 10° of heel. This distribution of floatation also makes it nigh on impossible for them to capsize, though the distance between the hulls can make it a problem in the rare cases that they do flip. They do suffer a bit from not having any wetted surface underneath the center of effort, causing them to slide sideways while sailing upwind and making it difficult for them to beat tight angles to the breeze. While they make up for this with speed on the reach and downwind, catamarans are an inferior option for trying to make progress upwind in heavy sea and wind conditions.
These tradeoffs do come with some advantages. Unlike monohulls, catamarans have very shallow drafts, allowing cruisers to sail close to shore without concern, and their common dual-motor design allows them to maneuver incredibly well in tight spaces with a built-in backup for single-engine failure. They heel minimally because of the horizontal distribution of weight, and this means that they are incredibly stable and comfortable while underway or at anchor. In addition, their sail plans and maneuverability characteristics do make them easier to sail with a smaller crew, requiring fewer highly experienced sailors in your party.
Trimaran: Speed and Safety
While traditionalists have finally come around on the aesthetics of the dual-hulled catamaran, the tri-hulled lines of trimarans can still be a bit of a shock to viewers. They combine the vertical stability and upwind capabilities of a monohull with the speed and lateral stability of a catamaran.
When it comes to performance sailing, modern trimarans are well ahead of any other hull design. Due to the relationship between speed and the ‘waterline length’ of a boat, i.e. that more hull length in the water leads to higher speeds, the third hull actually makes trimarans drastically faster than any other hull shape at a given length. Most current speed records, including those for circumnavigation, instantaneous velocity, and single-day distance, are held by Trimarans. In competition, the 2013 America’s Cup is a perfect example of the superiority of Trimarans over Catamarans in terms of speed, as the challenging Trimaran from Golden Gate Yacht Club handily beat the defending Spanish Catamaran in a best-of-three series. With their signature central hull, they can make better upwind progress without drifting and often heel even less than contemporary catamarans.
Further, trimarans far outclass both catamarans and monohulls in terms of safety. The central hull gives the trimaran that signature central righting moment from monohulls, while its winged pontoons provide it the lateral balance that makes catamarans so safe themselves. Combined, this gives a modern trimaran a righting moment of 27°, which is almost impossible to reach in any breeze condition because of the pontoons. For a comparison, modern cats can only maintain 12° of heel before flipping, which is not entirely uncommon in heavy seas.
Therefore, in a purely technical sense, trimarans are safer, speedier, and more rewarding. Still, to reap these benefits you often need to be a little more prepared to engage with the more advanced aspects of sailing, and the tri-hull design does make some sacrifices in other areas.
Comfort
Though performance is an important metric for all sailboats, every added knot of speed or degree of heel comes at a price of comfort, and it is here that we need to consider the full implications of that cost for both cats and tris.
Catamaran: The Ideal Platform
When it comes to comfort, space, and luxury, it is hard to bet against the catamaran. Because of the geometry of the dual deep hulls and built-up central platform, catamarans offer the ideal vessel for a large crew, a party yacht, or a comfortable getaway vessel. They heel minimally, are highly stable at anchor, and the central platform can be carefully built to maximize the area between the wings. Most catamarans can offer the living space and horizontal area of much larger monohulls, making it the ideal choice for a pleasure cruise.
Trimaran: The Cost of Speed
For all their advantages in terms of performance, the hardware required for the central hull subtracts substantially from the accommodations that are available for a cat of the same size. New trimarans, like the Neel 51 which made waves back in 2017, are pushing back against this perceived comfort gap, the large central hull with the two performance-oriented wings does make it harder for tris to haul the same amount of weight and provide comparable space as most cats.
Preferences
The beauty of modern sailboats is that design advances in both catamarans and trimarans make it possible for all sailors to find the exact right boat for them. Speed demons who want to sail tight to the wind and feel that rush may find themselves enticed by the capabilities of the newest Trimarans, while cruisers looking to get the biggest space for the length are still thrilled by how fast and stable modern Catamarans are off the breeze. While no one would complain about being invited to a cruise on a new Trimaran, you can certainly fit more of your friends in the spacious decks of a Cat.
Both multi-hull styles excel at maneuvering in small spaces and shallow waters, perfect for island hopping or inland sailing. Their wide platforms, which can run a slightly higher cost at marinas than comparable monohulls, enable stability without sacrificing performance. Both are regarded as incredibly safe in nearly all conditions, though Trimarans do have the slight edge in truly nasty weather.
In the end, it all comes down to how you want to sail and what is going to make a good trip successful! For those looking for a leisurely cruise with a minimum of work and a maximum of space, find the most spacious catamaran you can, and don’t worry about missing out on speed as you’ll more than hold your own off the breeze. If you’re excited to go fast no matter what direction the wind is coming from, with the knowledge that you’re nigh on unsinkable, a performance trimaran is the way to go!
Happy Sailing!
