At first glance, the various cruising catamarans on the market may seem quite similar, yet there are many design characteristics that distinguish one boat from the next. If you are in the market for a cruising cat, one of the main design features that will influence your decision will be whether the boat has fixed keels or daggerboards. As with so many boat characteristics, there are advantages and disadvantages to both. In this article I'll help you determine which is best for your needs.
Both fixed keels and daggerboards help a boat to track smoothly and prevent leeway. Centerboards perform the same function, but they are more commonly found on trimarans. The Gemini 105M from Performance Cruising, which has twin centerboards, is a notable exception. Some designs such as the Maine Cat 30 have a single daggerboard in one of the hulls. This novel approach requires less effort and works reasonably well since cruising cats have no appreciable angle of heel under sail.On catamarans with fixed keels, the low-aspect-ratio design of the keels is a compromise between ease of operation, performance, and safety. The depth of the keel is an important consideration. The keels must be deep enough to give adequate performance to windward, yet shallow enough to allow the boat to ride the waves comfortably without tripping and to take advantage of one of this breed's greatest assets, the ability to cruise shallow waters. Fixed keels are easy on the crew. there's nothing to think about, nothing to raise and lower when changing angles of sail or water depths. That's why almost all cats in the bareboat charter trade have fixed keels. Fixed keels also provide a convenient surface for the boat to rest on when it's hauled out or left to dry out at low tide. Some boats have replaceable "shoes" on the keels that take the brunt of the abuse from these practices.
Daggerboards are most often found on boats where the designer has stressed higher performance. Daggerboards offer advantages at both ends of the spectrum: they provide good sailing performance with the boards down, particularly when sailing to windward, and they also allow for extremely shallow-draft gunkholing when the boards are up. These examples illustrate the true significance of daggerboards. the fact that they allow the crew to adjust the boat to a wide variety of sailing conditions. In most conditions daggerboards (or centerboards) offer greater precision and flexibility than fixed keels. However, some potential drawbacks to daggerboards are that they may be difficult to raise and lower in certain conditions, and that they might even become stuck in place in the event of an encounter with a fixed object or some flotsam or jettsom.
In general, tris and cats with centerboards or daggerboards will make less leeway than boats with fixed keels. Prospective owners can get the predicted leeway angles from the builder or designer.
Here are some tips on daggerboards: On catamarans with a daggerboard in each hull, use both boards down in light winds to give the boat the most lift. In moderate winds, use the leeward board since it will be in slightly deeper water. As you gain speed or fall off the wind, the daggerboard can be gradually raised; experience will tell you how much is best for your boat in various conditions. If high boat speeds make it difficult to raise the board, you'll have to reduce speed temporarily to ease the pressure on the board in its trunk. Keep the board(s) down partially for a beam reach to minimize leeway, then raise the board(s) gradually as you sail further off the wind. Experience will tell you exactly where to place the board(s) in various conditions; it's best to keep a foot or so of board down when running to improve steerage.
Both of the cruising catamarans I have owned had fixed keels. As a cruising family we found them a great convenience, and more than once our boat was perched high and dry on her fixed keels with no adverse effects. Even so, I always thought I would like to try cruising on a boat with daggerboards, if only so I could sneak a little farther up into those cozy protected places in the anchorage.