Decision 35 Information, Review, Specs

Sailing Performance & Handling

The sailing characteristics of the Decision 35 are defined by its extreme light-air efficiency. With a displacement of only around 1,200 kilograms and a towering carbon fiber rotating mast, the boat possesses an extraordinary sail area-to-displacement ratio. According to technical archives from the Bol d’Or Mirabaud, the D35 was engineered to reach its maximum hull speed in as little as 5 to 6 knots of true wind. Its handling is described as surgical; the twin high-aspect-ratio hulls provide minimal wetted surface area, allowing the boat to accelerate instantaneously out of tacks.

On the helm, the D35 is notoriously sensitive. Because it lacks the weight of a traditional ocean-going catamaran, momentum is quickly lost if the helmsman fails to maintain a clean flow over the deep daggerboards. In heavier air, the boat requires an elite level of coordination; the massive square-top mainsail and the reacher (gennaker) generate significant righting moment challenges. While it does not utilize the modern hydrofoils found on its successor, the TF35, the D35 "flies" its windward hull early and with stability, provided the traveler and mainsheet are trimmed with constant vigilance. Technical reviews in European sailing journals often highlight the boat's ability to "vmg" (Velocity Made Good) upwind at angles that seem impossible for a multihull of its era.

Popular Mentions & Media

The Decision 35 is inseparable from the history of the Bol d'Or Mirabaud, the world’s most prestigious inland lake race. For over a decade, the D35 was the undisputed queen of the lake, claimed by legendary sailors such as Ernesto Bertarelli of Team Alinghi and Loïck Peyron. The class was the primary vehicle for the Vulcain Trophy, a professional racing circuit that drew international talent to the Swiss Riviera. The boat's cultural footprint is solidified by its dominance in Swiss sailing media, where it was frequently featured as the benchmark for multihull performance before the advent of foiling technology.

Known Issues & Buyer’s Checklist

Prospective owners of a pre-owned Decision 35 must approach the vessel as they would a high-performance aircraft rather than a recreational boat. Structural integrity and composite fatigue are the primary concerns.

• Carbon Delamination: Given the age of the original fleet, the carbon-Nomex sandwich hulls should be inspected for soft spots or delamination, particularly around the high-stress areas where the crossbeams (akas) join the hulls.
• Rigging Fatigue: The D35 uses a highly stressed, rotating carbon mast. The standing rigging, often made of PBO or high-modulus synthetic fibers, has a finite lifespan and requires rigorous replacement intervals to avoid catastrophic rig failure.
• Daggerboard Trunks: The lateral loads generated when sailing at high speeds can stress the daggerboard trunks. Check for stress fractures or weeping around the trunk-to-hull joins.
• Trampoline and Hardware: The expansive trampoline is a critical safety component and structural stabilizer. Look for UV degradation in the mesh and check the mounting points on the inner hull sheer lines for signs of pulling.

Community & Resources

The primary hub for this model is the D35 Class Association (Association des Propriétaires de Decision 35), which governed the one-design rules and organized the racing calendar for many years. Technical documentation and class rules are typically managed through the Lake Geneva sailing federations. While the professional circuit has largely transitioned to the foiling TF35, a robust secondary market exists for D35s among private racing syndicates and high-end lake sailors.

The Verdict

The Decision 35 remains one of the fastest non-foiling multihulls ever built for inland waters. It is a purist's racing machine that offers a level of refinement and acceleration that few modern boats can match without the complexity of foils.

Pros:

• Unrivaled light-air performance; capable of outrunning the wind in ghosting conditions.
• Strict one-design heritage ensures a high build quality and consistent performance across the fleet.
• Prestige and provenance associated with the Alinghi era and Bol d'Or history.

Cons:

• Strictly a racing platform with zero interior amenities or "cruising" potential.
• Requires a highly skilled professional or semi-professional crew to sail safely in high winds.
• High maintenance costs associated with specialized carbon fiber components and high-tech rigging.