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post #1 of Old 11-18-2003 Thread Starter
Kevin Jeffrey
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Tacking and Jibing a Multihull

With two broadly spread hulls, most catamarans require a little special attention when tacking to avoid getting stuck in irons.
Basic tacking skills are important aboard every sailing vessel, but they’re particularly emphasized in multihull sailing. If you don’t tack a multihull properly, there’s always the chance that you can stall the vessel, putting it into irons, which can have dangerous consequences depending upon where you’re sailing.

When you're ready to come about on a multihull, do it decisively, and make sure you are close to the wind yet still maintaining good speed. Trim the mainsheet in hard before tacking. This will allow the mainsail to act like the aft section of a windvane, helping swing the boat into the wind. Find a lull in the waves and bring the helm over smoothly, and keep it there until you approach 45 degrees off the wind on the new tack. At that point slowly reverse the helm to bring the boat onto your new heading.

It’s really that simple, but you’d be surprised at the number of novice multihull sailors who get themselves into trouble tacking. As you pass through the wind, ease the mainsheet a bit to reduce the windvane effect, which is no longer needed, and to allow the mainsail to fill and provide power on the new tack. If you lose momentum during the tack and need to backwind the jib, delay the release of the headsail sheet until the back side of the jib has filled and is pushing the boat off the wind on the new tack. As soon as you're well through the wind, but no further than necessary, release the windward sheet and haul the leeward sheet in quickly to get the boat moving forward again. Always trim the jib first and then the main. And by all means allow the boat to pick up speed before trying to sail close-winded again.

When a puff hits aboard a multihull, it's usually better to bear off and avoid the additional heeling that heading up might create.
When sailing close-hauled aboard a monohull in windy conditions, the standard practice is to head up or "feather" the helm when a gust hits. This helps to prevent the excessive heeling that can result from a strong puff. But in these conditions, falling off the wind is a better technique for most multihulls, since heading up can accelerate the boat temporarily, which often tends to submerge the leeward bow of a catamaran or ama of a tri. Falling off in a gust is good practice, but less of a concern on boats with high-buoyancy bows.

When sailing to windward, you'll have to allow for additional leeway in any shallow-draft boat. Daggerboards help reduce leeway by offering resistance under the water. Use the recommendations of your boat's builder or designer along with your own experience under sail to determine how much daggerboard to deploy in various sea conditions. On catamarans that have a daggerboard in each hull or trimarans with a board in each ama, use both boards in light winds to give you the most lift. In moderate winds, use only the leeward board since it will be in slightly deeper water as the boat heels. As you gain speed or fall off the wind, the daggerboard can be raised gradually. High speeds can make it difficult to raise the board, so you may find that you have to reduce speed temporarily to ease the pressure on the board.

Reaching is the perfect point of sail for most multihulls.
Sailing off the wind is a breeze in a multihull, with reaching the perfect point of sail for a cat or tri. The sail trim you employ is the same as that for a monohull, although faster multihulls will bring the apparent wind forward so that a reach may become close-hauled sailing and you'll find yourself trimming the sails in closer. Make sure that the forward sections of the boat aren't too heavily loaded when sailing downwind as this increases the tendency of the bows to dig in. High-performance multihulls usually sail downwind by "tacking" at 45-degree angles off the wind. This increases boat speed and shortens passages considerably.

If your boat has daggerboards, raise the boards gradually as you head off the wind. When running, have the boards almost all the way up, immersed just enough to improve steerage. You will probably want to use some more daggerboard in stronger winds to help unload the pressure on the rudders. With so little heel, the typical rolling motion of a monohull is all but eliminated on a multihull, and the tendency to broach is greatly reduced. And that’s good news because less roll means less chance of accidentally jibing.

Even if you do jibe suddenly, intentionally or not, it will undoubtedly seem like a routine maneuver, since chances are the boom will be well above head height. The boom and mainsail foot on most multihulls are of modest proportions, and with the boat traveling at a good rate of speed, all you have to do is avoid the mainsheet and the traveler as they come across the boat and you’ll be safe and sound.

"With so little heel, the typical rolling motion of a monohull is all but eliminated on a multihull, and the tendency to broach is greatly reduced. "

To jibe intentionally, begin turning the boat downwind as the mainsail (both the sheet and the traveler) is trimmed to bring the boom on centerline. As the boat turns and the mainsail passes through the wind and begins to fill on the other side, ease the mainsheet and set for a broad reach. Make sure to maintain boat speed to keep the apparent wind light. Release the windward jib sheet and trim the leeward jib sheet.

Many multihull cruisers like to dowse the mainsail and fly twin headsails downwind, with one sail poled out on a permanently mounted whisker pole. Twin headsails can be rigged using twin forestays, twin grooves in a roller-furling track, or a two-ply headsail. Use a working jib and genoa in stronger winds, then a genoa and drifter in lighter winds until it's time for a spinnaker. With little rolling to contend with and no main to block the wind, both sails tend to stay full. Average speeds with this rig are usually impressive.

The broad decks and tramps of a multihull make the mechanics of flying a spinnaker even easier than on a monohull.

If you choose to fly a spinnaker, you'll find that it's much easier on a multihull because of the wide foredecks. Occasional surfing down the backside of a wave is normal for a multihull, but consistent surfing is a warning telling you that it’s time to reduce sail. While you’re still learning what your boat can do and how it behaves in different conditions, it's best to reduce sail early. The speed of a multihull makes the apparent wind relatively light, so reef as though you were sailing to windward, which you may have to do suddenly.

When you’re maneuvering a multihull under sail in tight anchorages or around docks requires some practice, particularly with some of the heavier cruising cats that lack good, crisp response to the helm. Give yourself some additional time and distance to turn, and be aware of how quickly a multihull can accelerate in a gust or come to a stop once headed into the wind. Just play your main and jib just as you would with a monohull, and once you find your preferred anchoring spot just allow a sufficient amount of runway and head up into the wind so that you can drop your hook. After that you'll be ready to relax and enjoy all of that additional deck space that multihulls offer.

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