Beginner's Guide to Trimming a Diam 24 Trimaran

A Simple Three-Sail Plan

Start with the rig, because it's simpler than it looks. A Diam 24 carries just three sails: a square-topped main, a small self-tacking jib, and a furling gennaker for reaching and downwind. There's no genoa to grind through every tack, no overlapping headsail to manage, and no separate spinnaker set to learn — a minimal inventory that's part of what makes the boat approachable for sailors who haven't raced a multihull before.

Because the jib mostly takes care of its own trim as you tack, your attention as a beginner should go almost entirely to the main. It's the sail doing the most work, and it's the one where small trim mistakes cost you the most speed. Get comfortable with mainsail trim first, and the jib and gennaker will feel like much smaller additions later.

Why Your Weight Doesn't Go to the Windward Float Right Away

This is the part that surprises almost everyone coming from a beach catamaran or an F18. On those boats, the instinct to hike out hard kicks in almost as soon as there's breeze worth holding — more wind means more weight on the windward hull, right from the start. Bring that instinct straight over to a Diam 24 and it arrives too early.

In light air, crew weight stays forward and low — often on the leeward side, not the windward float — because there's no heeling force yet worth countering, and the priority is bow-down trim rather than leverage. As the breeze builds past about ten knots, the boat starts flying its main hull clear of the water, and crew position shifts toward the center and cockpit to support that lift. Real hiking does come, but only once you're solidly powered up past around twelve knots — noticeably later in the wind range than a beach cat trains you to expect.

Before you obsess over sheet tension or leech telltales, get comfortable with this sequence: forward and low when it's light, centered through the transition, hiking once you're powered up. Getting the timing right affects the boat's speed and stability more than any individual sail control — and it's the sequence a monohull or beach-cat background won't have prepared you for.

Mainsheet and Traveler: Your Primary Power Controls

Once your weight is in the right place, mainsail trim is where you'll spend most of your focus. Like most performance multihulls, the Diam 24 doesn't heel the way a monohull does, so you don't get that natural feedback of the boat leaning over to tell you when you're overpowered. Instead, you have to read the sail and the platform directly.

Use the traveler to set your baseline power — closer to centerline in light air, eased down as the breeze builds — then work the mainsheet actively, easing as puffs hit rather than waiting until the boat is already loaded up and hard to control. Multihulls accelerate quickly, and a Diam 24 rewards a sailor who anticipates gusts rather than reacts to them.

For a real-time gauge, watch the top batten or the leech telltale at the head of the sail. Stalled and tucked behind the leech means you're over-trimmed. Flogging constantly means you're under-trimmed and leaving power on the table. That telltale will tell you more than how the boat feels underneath you, especially early on.

Jib and Gennaker: Simpler Than They Look

The self-tacking jib is low-maintenance by design. You'll set it up once for the conditions and mostly leave it alone through your tacks, checking leech tension occasionally rather than treating it like a genoa that needs constant grinding. It's one less thing to think about while you're still learning the main.

The furling gennaker is where new sailors most often get caught out. It loads up fast on a reach and the instinct is to keep it trimmed a moment longer than you should. Ease it before a gust overpowers you, not after you're already struggling to control the boat. Treating the gennaker ease as an early, proactive move — rather than a last resort — will save you from most of the sketchy moments beginners run into on this boat.

Building Trim Feel: Start Moderate, Add Power Gradually

Trim feel on a Diam 24 comes from repetition, not theory, so how you structure your practice time matters. Start in moderate breeze — somewhere in the 10-to-15-knot range — rather than pushing straight into max conditions. That's enough wind to feel the main hull lift and notice how your weight and sail trim interact, without being on the ragged edge where every small mistake turns into a scramble.

Sailing with a coach or an experienced Diam 24 crew speeds this up considerably. Someone who can call out corrections in real time — move forward, ease now, hold that trim — turns abstract advice like “watch the telltale” into something you can actually feel and repeat. Trial and error works eventually, but structured feedback gets you there faster, with fewer bruising moments along the way.