Catamaran Spotlight: 7 Things You Didn’t Know | Episode 1

More and more boat builders are offering motor catamarans. This is a clear sign that more and more recreational boaters are buying them. While finding a non-sailing multihull 20 years ago was a challenge, today there are at least 14 manufacturers producing them. Why this shift? For one thing, it became apparent that many owners of sailing catamarans were using their boats exclusively under motor power—so why not just remove the mast and all the structural reinforcements it requires? But catamarans offer many advantages.

1. First, for the same length, they offer between 65 and 70 percent more space (catamarans are not twice as wide as a monohull of the same length). This makes a big difference, and the visual impact is striking: step aboard a 40-footer and you’ll find the saloon, the forward cockpit, and the bow cockpit or sun deck—features you’ve only seen on a 60-footer. In fact, the bow retains virtually the maximum beam, so to have the same amount of space forward of the deckhouse, you’d have to go for an 80-footer. It’s clear that something like this makes a big impression.
2. Second, catamarans are more stable at anchor and while sailing: on one hand, there is a single hull that is about one-third as wide as it is long; on the other hand, there are two hulls—that is, two points of support with a base that is two-thirds of the width.
3. Third, they are no longer fragile: the old fears that the boat might be torn apart by rough seas because the crossbeams couldn’t withstand the erratic movements of the two hulls can be put to rest, since the central hull and the two hulls are now constructed as a single unit: crossbeams are no longer used to join the hulls to each other or to the central hull.
4. Fourth advantage: technical and service areas can be larger, since there’s much more space available—it makes no sense, for example, to sacrifice walkways when you already have one and a half times the space inside compared to a monohull.
5. Fifth advantage: greater privacy. It’s not uncommon for an owner to have an entire hull dedicated to their sleeping quarters.
6. Sixth, there’s the issue of fuel consumption. Multihulls are more efficient when moving forward. If we limit ourselves to displacement catamarans—which make up the majority—the hulls have a very high length-to-beam ratio at the waterline: a monohull has a ratio of 3:1, a catamaran about 8:1, and according to the laws of hydrodynamics, the latter is the limit that eliminates constraints related to drag. In other words, a boat with a length-to-beam ratio of less than 8:1 can exceed the speed limit imposed by its length at the waterline only by planing. If, on the other hand, this ratio is higher, this constraint no longer applies, and as is well known, keeping a hull planing requires a great deal of energy. It is no coincidence that almost all catamaran manufacturers use hulls that have a much narrower cross-section below the waterline than above it.

A drawback? There is one: the issue of boat slips, specifically the fees charged by marinas for mooring. Things have changed here as well: while ten years ago rates were typically double those charged for a monohull of the same length, today many marinas—notably three in particular: Marina di Varazze, Marina dei Cesari, and Marina Sveva—offer preferential rates for catamarans. Otherwise, it’s always possible to work out an arrangement with the marina operator, since in almost all marinas—especially in Italy—there are more berths than boats.