Design Brief & Intent
The core mission of the Nacra 5.5 Sloop was to deliver uncompromising, race-ready speed on a stable and hydrodynamic platform. In an era dominated by the banana-shaped, asymmetrical hulls of early recreational catamarans, the Nacra 5.5 introduced symmetrical fiberglass hulls with highly efficient, vertical plumb bows and reverse transoms. This design dramatically reduced "hobby-horsing" (the tendency to pitch up and down in chop) and allowed the hulls to slice through waves rather than riding over them. The hull cross-section is a distinct "teardrop" shape, concentrating volume higher up to provide substantial reserve buoyancy forward. This acts as a vital safety buffer against pitchpoling—the dramatic nose-diving capsize common in early multihulls when sailing downwind in heavy air.
Constructed of fiberglass utilizing a foam-core sandwich technique, the platform achieved a remarkably low displacement while maintaining the necessary structural rigidity to handle high rigging tension. True to its performance brief, there is no interior cabin or yacht-like joinery; the "cabin" of the Nacra 5.5 is its spacious trampoline deck. This deck serves as an athletic workspace, outfitted with heavy-duty hiking straps, high-aspect Harken block systems, and dual trapeze lines. It was designed strictly for a crew who prioritized raw speed, physical engagement, and tactical racing over cruising comfort.
Variations & Configurations
The 5.5 platform was produced in two distinct configurations built on the same high-buoyancy hulls: the single-handed Nacra 5.5 Uni (or Cat-rigged) and the double-handed Nacra 5.5 Sloop (also known as the 5.5 SL). The Uni rig featured a larger, taller mainsail designed to be sailed solo with a single trapeze. The Sloop configuration utilized a fractional sloop rig, adding a high-aspect jib to the rotating mast, which expanded the total sail area to 241 square feet. This setup required a active two-person crew, utilizing double trapezes to balance the immense power of the rig.
While the original Nacra 18 Square Meter class catamarans utilized a massive, highway-illegal 11-foot beam that required specialized tilting trailers to transport, the Nacra 5.5 Sloop was built with a standardized, road-legal 8.5-foot beam. This narrower beam significantly broadened the boat’s appeal, allowing owners to easily trailer the catamaran to regional regattas without special permits. Under the water, the 5.5 Sloop features deep, high-aspect retractable daggerboards. With the boards fully extended, the draft reaches 2.83 feet, providing exceptional lift and pointing ability upwind; with the boards raised, the draft drops to mere inches, allowing the boat to be sailed directly onto sandy beaches.
Sailing Performance & Handling
At the helm, the Nacra 5.5 Sloop is an absolute thoroughbred. With a remarkably low displacement of only 375 pounds and a substantial sail plan, the boat features an astronomical sail-area-to-displacement ratio of 74.15. In physical terms, this high ratio translates to explosive acceleration in light-to-moderate air. It is a highly responsive boat that feels alive even in a five-knot breeze, where it can easily fly the windward hull. However, this extreme power-to-weight ratio demands constant attention and athletic intervention from the crew as the breeze builds; managing the power of the rotating mast requires active mainsheet and traveler trim.
The high capsize screening ratio of 4.72, while traditionally applied to monohull stability calculations, highlights the catamaran's wide beam-to-displacement profile. In practice, the 5.5 is a highly stable platform until it reaches its tipping point. Symmetrical hulls with deep daggerboards allow the 5.5 Sloop to point far higher and slide sideways far less than boardless, asymmetrical beach cats. Tracking is exceptionally precise, and the helm provides instantaneous feedback. For a well-coordinated crew on the double trapeze, the boat locks into a groove downwind, delivering high-speed rides that can easily match or exceed the wind speed.
Market Snapshot & Economics
On the brokerage market, the Nacra 5.5 Sloop occupies a highly appealing, value-driven niche. Because it is no longer in active one-design fleet production, it does not command the steep pricing premiums of modern Formula 18 or Nacra 17 Olympic-class racers. Instead, it serves as an economical entry point for sailors looking to experience near-Olympic levels of catamaran performance without a massive capital investment.
Well-maintained examples are relatively scarce because many vintage units were raced hard or left exposed to the elements, but those in good condition represent excellent recreational value. Buyers should budget for the immediate replacement of soft trampolines, standing rigging, and aged sails, as high-performance catamaran components operate under immense physical loads and degrade over time. Fortunately, because Nacra remains a premier multihull builder, aftermarket parts, upgraded trampolines, and performance sails are still widely manufactured and readily accessible.
Known Issues & Triage
For prospective buyers, the primary concern when evaluating a vintage Nacra 5.5 Sloop is fiberglass delamination, commonly referred to as "soft spots". Because the hulls are built using a foam-core sandwich construction, years of crew standing on the decks or the crushing force of the front crossbar casting can cause the outer fiberglass skin to separate from the internal foam core. Triage requires physically pressing on the decks, especially forward of the front beam; any flexing or hollow cracking sounds indicate delamination. This is repaired by drilling a grid of small holes, injecting low-viscosity epoxy, and applying heavy weights or vacuum bagging to rebond the skin to the core.
Daggerboard trunks are another high-stress zone. If a previous owner ran the boat aground at high speed with the daggerboards down, the impact forces can crack the internal trunk-to-hull joints, leading to persistent leaks. Prospective buyers should inspect these areas internally for stress cracks or evidence of crude fiberglass repairs. Additionally, the original rope-and-cam operated kick-up rudders are prone to developing excessive play or "slop" at the pivot pins over decades of use. This wear leads to severe helm vibration at high speeds and a loss of steering sensitivity, which often necessitates shimming the rudder blades or rebuilding the housings.
Modernization & Upgrades
Many dedicated owners have successfully modernized the Nacra 5.5 Sloop to keep pace with contemporary catamaran designs. The most common and impactful upgrade is the installation of an asymmetric spinnaker (or gennaker) kit. Retrofitting an aluminum or carbon bowsprit and a tramp-mounted snuffer bag allows the crew to launch a massive downwind chute. Using a single-line halyard and tack system allows the sail to be raised and the tack pulled to the end of the pole simultaneously, simplifying handling to the point that even solo sailors can manage the spinnaker downwind.
Another popular modification involves upgrading the steering system. Replacing the original, high-maintenance rope rudders with more positive-locking, spring-loaded "Inter" rudders from later-generation Nacra models drastically improves helm reliability and reduces steering drag. Performance-minded owners also replace worn-out Dacron sails with modern, square-top (fathead) laminate sails made of PEN X-Ply or Mylar. These modern cut designs allow the head of the mainsail to twist open in heavy gusts, self-depowering the rig and significantly increasing the boat's safe wind range. Lastly, replacing traditional wire standing rigging with low-stretch, synthetic Dyneema shrouds and forestays reduces weight aloft, improving both stability and responsiveness.
The Verdict
The Nacra 5.5 Sloop remains an outstanding, vintage high-performance beach catamaran that offers incredible speed, precise handling, and an athletic sailing experience for a fraction of the cost of a modern racing cat. While it requires active, skilled crew work and is unforgiving to novices in heavy air, its advanced hull design, robust parts availability, and easy trailering make it an enduring favorite among multihull enthusiasts.
Pros
- Exceptional speed and explosive acceleration, especially in light-to-moderate wind
- Deep daggerboards and plumb bows provide superb upwind tracking and point higher than boardless catamarans
- High-volume teardrop hulls offer excellent reserve buoyancy, reducing the risk of pitchpoling
- Road-legal 8.5-foot beam makes trailering and transport straightforward
- Highly adaptable platform that supports modern upgrades like asymmetric spinnakers and square-top laminate sails
Cons
- Demands highly active, athletic crew work; not suitable for novice sailors
- Susceptible to hull delamination and soft spots in high-stress deck areas
- Complex rigging and dual trapezes require significant set-up and breakdown time at the beach
- Aging rudder systems can suffer from slop and vibration unless upgraded or meticulously maintained
