Design & Layout
At the core of the Catalac 10’s appeal is its robust construction. The hulls are laid up with solid fiberglass of exceptional thickness. According to yard lore, the design was executed in metric and converted to imperial by a builder who substantially overestimated the required laminate schedules, resulting in a layup that was effectively twice as strong as structurally necessary. This structural margin is most visible on the foredeck, which in some areas measures several inches of solid fiberglass, offering an incredibly rigid platform that does not flex under windlass loads. While the hulls are solid, the decks utilize an end-grain balsa core for weight management. A notable design distinction of the era is the use of tempered safety glass for all salon windows rather than the cheaper, UV-prone Plexiglas or acrylic used by competitors—a feature that keeps the interior clear, dry, and exceptionally well-insulated against the elements.
The interior layout defies the typical modern "condo-maran" aesthetic, opting instead for a cozy, highly practical, sea-kindly arrangement. The bridgedeck cabin features a spacious U-shaped salon with panoramic visibility, giving helmsmen the ability to monitor the horizon from a protected, climate-controlled environment. Accommodations are spread across the two hulls. Typically, the boat was configured with two large forward double cabins and a single, spacious head. In the starboard hull, the standard layout featured a small aft cabin; however, many owners opted for—or subsequently retrofitted—the "extended pantry" configuration. This highly sought-after variation replaces the starboard aft berth with a massive, continuous galley and pantry extension, creating an exceptional amount of countertop space and storage that is ideal for long-distance cruising.
With a beam of 15 feet 6 inches, the Catalac 10 strikes a perfect compromise for coastal and canal cruising. It avoids the hefty "double-slip" marina surcharges often leveled at modern, ultra-wide catamarans and is narrow enough to navigate many standard slips and inland waterways, such as the French Canal system.
Sailing Performance & Handling
The sailing performance of the Catalac 10 is characterized by stability and predictability rather than blistering racing speeds. With a displacement of 12,300 pounds and a displacement-to-length ratio (Disp/LWL) of 278.98, it is a heavy vessel for its length. This mass, combined with a modest sail-area-to-displacement ratio (SA/Disp) of 18.49, ensures that the boat is highly stable and does not easily become overpowered. The capsize screening ratio of 2.64 and a comfort ratio of 17.41 underscore a motion comfort level that is highly reassuring for families transitioning from monohulls. The low center of effort, driven by a conservative masthead sloop rig, ensures that the boat sails exceptionally flat. No Catalac has ever been recorded flying a hull, and the design is highly resistant to pitch-poling under sensible cruising canvas.
At the helm, the Catalac 10 feels solid and tracks remarkably straight due to its shallow, fixed long keels. However, because it lacks deep daggerboards, its ability to point high into the wind is limited, and tacking requires maintaining adequate boat speed to prevent getting caught in irons. In short, steep head seas, the boat can suffer from bridgedeck slamming—a common trait for catamarans of this vintage with relatively low bridgedeck clearance. Off the wind, however, the vessel is a comfortable and steady performer, easily averaging six to seven knots on extended passages.
Mechanical & Propulsion Configurations
Propulsion is one of the Catalac 10’s strongest suits, generally featuring a twin-engine diesel configuration connected to sail drives. Most models were fitted with twin Yanmar diesels, ranging from the lightweight 9-horsepower Yanmar 1GM10 up to the more robust 27-horsepower Yanmar 3GM series 2. The twin-engine setup, coupled with twin rudders, provides remarkable maneuverability in tight spaces, allowing the boat to literally spin on its own axis.
The physical placement of these engines is highly unique: they are mounted significantly forward in the engine compartments, placing the weight closer to the boat's center of gravity to prevent hobbyhorsing. While this mid-engine mounting maximizes hull balance and minimizes stern squatting under power, it creates a notable maintenance challenge. The front of the engines, where critical service items like the raw-water pump, oil filter, thermostat, and alternator belts are located, sits only a few inches from the forward engine-room bulkhead. Owners must often utilize inspection mirrors or perform blind hand maneuvers to complete routine oil and filter changes.
Known Issues & Triage
While the solid fiberglass hulls of the Catalac 10 are practically immune to catastrophic structural degradation, the balsa-cored decks are vulnerable to moisture intrusion. Areas around stanchion bases, cleat mountings, and the mast step must be closely monitored with a moisture meter. If water has penetrated the balsa core, local recoring and re-bedding of the hardware are required to prevent soft spots from developing.
Another era-specific quirk is the builder’s integration of the electrical wiring. Tom Lack occasionally embedded the primary wiring harnesses directly into the fiberglass layup of the hulls during construction. Over forty years later, these original wires are prone to degradation. Because they cannot be pulled out of a conduit, modernizing the electrical system usually requires cutting the old wires flush and running completely new marine-grade wiring through newly installed surface-mounted conduits.
Finally, the steering system demands consistent preventative maintenance. The hydraulic steering on later models is generally trouble-free, but those with mechanical cable-steering systems often suffer from heavy helm pressure if the cables are dry or out of alignment. Steering cables must be kept tensioned and thoroughly greased, and the alignment of the lead blocks in the aft lockers should be verified to prevent premature cable wear.
Modernization & Upgrades
For owners looking to modernize a Catalac 10, the vessel’s flat, expansive cabin top offers an ideal platform for high-output solar arrays. Installing multiple rigid solar panels on the cockpit hardtop can easily generate enough power to support a modern lithium iron phosphate (LiFePO4) house battery bank, eliminating the need to run the diesel engines for house loads.
Additionally, because the original Yanmar 1GM10 engines are considered underpowered by modern cruising standards, many owners undertake repowering projects. Upgrading to twin Yanmar 2YM15 or 3YM20 engines provides the necessary thrust to push through heavy head seas and windage without significantly increasing the weight in the stern.
The Verdict
The Catalac 10 is a rugged, highly dependable cruising catamaran that offers the interior living space of a much larger monohull within a compact, easily managed footprint. It is an ideal option for budget-conscious cruisers, coastal explorers, and those seeking a proven, flat-sailing platform capable of crossing oceans in safety. While it will never win races or point close to the wind, its overbuilt construction, redundant twin-engine layout, and sensible interior make it a standout classic in the multihull market.
Pros
- Extremely robust, overbuilt solid fiberglass hull construction
- Double-engine configuration with twin rudders provides exceptional dockside maneuverability
- Highly practical interior with durable tempered safety glass and an available extended galley
- Conservative beam avoids wide-slip premium fees at marinas
- Flat, stable sailing characteristics with a very low risk of capsizing or pitch-poling
Cons
- Low bridgedeck clearance leads to noisy slamming in short, choppy head seas
- Poor windward sailing angles and slower overall performance compared to modern daggerboard catamarans
- Engine access is tight and awkward due to the forward, mid-hull engine placement
- Original wiring is often embedded in the fiberglass, complicating modern electrical upgrades
- Balsa-cored decks are susceptible to soft spots if hardware is not regularly re-bedded
