Variations & Configurations
Though designated as the SL 15.5/16, the platform actually shares a single, highly refined 4.80-meter hull design. The fundamental distinction between the two models lies entirely in the rig configuration and the corresponding level of performance, making the platform brilliantly modular. The SL 15.5 was designed as a forgiving regional trainer and cadet class, featuring a 7.3-meter aluminum mast, an 11-square-meter mainsail, a small 2-square-meter jib, and a single trapeze. It was quickly adopted by the French Sailing Federation as a standard national pathway boat due to its docility and ease of handling for mixed or younger crews.
In contrast, the SL 16 is the high-performance variant. To elevate the platform to international racing standards, Yves Loday designed a larger, much more powerful rig featuring an 8.0-meter mast, a fat-head 13.75-square-meter mainsail, a 3.75-square-meter jib, and a massive 17.0-square-meter asymmetric spinnaker launched from a bow-mounted snuffer system. The SL 16 also features dual trapezes to allow both helm and crew to fully support the increased righting moment required by the larger sail plan. Crucially, Sirena Voile recognized the financial constraints of clubs and private owners by offering an official rig conversion kit. This allowed owners to buy the simpler SL 15.5 hulls and later upgrade to the full SL 16 class specifications as their young sailors gained the weight, strength, and experience necessary to handle the high-powered rig.
Sailing Performance & Handling
With a featherweight displacement of just 335 pounds, the SL series boasts an incredibly responsive and lively feel at the helm. This ultra-light footprint, combined with the SL 16's generous sail area, produces an astronomical sail area to displacement ratio of 82.26. This translates directly to blistering acceleration, enabling the boat to slip into a plane in light breezes and easily exceed 20 knots on a wild spinnaker reach. The hulls feature a high-buoyancy, semi-wave-piercing bow design that represents a massive evolutionary leap over classic symmetrical hulls of the past. By carrying volume forward and using modern rocker lines, the SL hulls actively resist the tendency to pitchpole, or "pearl," when flying downwind under the asymmetric spinnaker.
The boat's capsize ratio of 4.38 reflects its high-performance DNA and willingness to fly a hull on a dime. While it is certainly an athletic machine that will capsize when pushed beyond its limits, the wide 7.6-foot beam provides a highly stable and predictable platform before reaching the tipping point, and the light weight of the platform means it can be righted relatively easily by a two-person crew. The design relies on molded-in skegs on the bottom of the hulls rather than deep daggerboards. This choice significantly simplifies handling, eliminating the mechanical clutter of daggerboard trunks on the trampoline and protecting the hulls from catastrophic damage during beaching or shallow-water sailing. While the lack of daggerboards means the SL cannot match the razor-sharp upwind pointing angles of high-end Formula 16 racers, it tracks remarkably well and allows sailors to focus entirely on sail trim, weight placement, and tactical racing decisions.
Market Snapshot & Economics
On the secondary brokerage market, the SL series holds a unique and somewhat niche position. It is relatively scarce in North America, where only a few dozen hulls were imported for youth championships, meaning that clean examples on this side of the Atlantic command a notable premium among sailing academies and performance catamaran enthusiasts. Conversely, in Europe—particularly in France and the United Kingdom—the boat is highly plentiful due to its long-term adoption by national sailing federations and sailing schools.
Prospective buyers should view the SL as a high-value entry point into high-performance catamaran sailing. Unlike older legacy designs that are cheap to buy but require extensive modernization, a used SL is usually ready to race or play with minimal upgrades needed, provided the spars and hulls are intact. Because the platform has been out of high-volume production for some years, buyers must budget for the reality of sourcing specialized replacement parts. While sails and basic rigging can easily be sourced from aftermarket loft specialists, original hardware components, rudder castings, and specific deck hardware must often be imported directly from European suppliers, meaning that shipping costs can quickly influence the economics of a complete refit.
Known Issues & Triage
Despite its robust sandwich polyester construction, the SL series is subjected to extreme structural loads, particularly when sailed hard in the twin-trapeze SL 16 configuration. Over years of hard racing, the primary areas requiring careful inspection are the aluminum crossbeam mounting pockets. The front and rear crossbeams connect directly to the hulls, and these connection points can develop hairline stress fractures in the gelcoat. If left unaddressed, these cracks can allow water to penetrate the laminate core, leading to localized soft spots and eventual structural failure. Tightening and inspecting the beam bolts is a standard triage routine.
Additionally, because the boat relies on integrated skegs instead of daggerboards, the bottoms of the hulls are highly prone to abrasive wear. Dragging the boat across sand, gravel, or concrete launch ramps will inevitably grind down the fiberglass layup on the skeg running surface. Veteran owners frequently triage this issue by applying sacrificial brass or stainless steel keel guards, or by rebuilding the skeg bottoms with epoxy thickened with high-density fillers and reinforced with glass tape. Finally, the aluminum rudder castings and crossbar linkages can develop excessive play over time. This wear leads to a loose, unresponsive helm, which can be remedied by replacing worn plastic bushings and ensuring the rudder kick-up mechanisms are properly tensioned and lubricated.
Modernization & Upgrades
Modernizing an older SL model typically centers on upgrading the control systems and running rigging to match contemporary racing standards. Many owners of older SL 15.5 platforms choose to convert them to the SL 16 specification by sourcing second-hand spars and the larger sail plans. For both configurations, replacing the original heavy polyester sheets with high-tech Dyneema lines yields immediate performance benefits by reducing stretch and weight.
Upgrading the spinnaker retrieval and snuffer system is another highly popular modification. Modern ring-snuffer systems allow for much faster, jam-free douses, which is critical when sailing shorthanded or in heavy air. Additionally, replacing the original mesh trampoline with a modern, high-tension PVC or vinyl mesh trampoline dramatically stiffens the entire platform, reducing torsional flex between the hulls and improving pointing ability upwind. Finally, adding modern hull-protection pads helps preserve the hull surfaces when beaching or during land transport.
The Verdict
The SL 15.5/16 remains one of the most successful youth sport catamarans ever designed, offering a masterful balance between high-octane performance and robust, user-friendly simplicity. Its selection as an international youth championship class is a testament to its design pedigree, while its shared-hull modularity offers a practical pathway for sailors to grow from intermediate cruisers to advanced racers. While sourcing specialized replacement parts can require patience for owners outside of Europe, the boat's forgiving hull dynamics, lack of daggerboards, and blistering speed make it a highly rewarding platform for anyone looking to experience the thrill of modern multihull sailing.
Pros:
- High-octane performance with an exceptional sail area to displacement ratio.
- Modern, high-buoyancy bow design that actively resists pitchpoling.
- Modular rig design allowing easy conversion from the training SL 15.5 to the racing SL 16.
- Skeg-hull configuration simplifies beaching and eliminates daggerboard maintenance.
- Robust sandwich polyester construction built to handle the rigors of sailing schools.
Cons:
- Limited availability and premium pricing on the secondary market in North America.
- Sourcing original manufacturer replacement parts can be difficult and expensive outside of Europe.
- Lack of daggerboards slightly compromises upwind pointing angles compared to dedicated racing catamarans.
- Aluminum crossbeam connections and hull pockets are prone to fatigue and stress cracking over time.
