Design Brief & Intent
The original Catalac philosophy was built around extreme ruggedness and family safety. Blue Water Catalacs maintained this core identity when updating the platform into the Catalac 900, but shifted the focus toward a more modern, liveaboard-friendly cruiser. The defining transformation of the 900 is its raised doghouse, which was expanded into a fully enclosed pilothouse. In the older 9M, the companionway hatch was a sliding cover with washboards that, when closed, restricted saloon headroom to a mere 4.5 feet. The Catalac 900 resolved this by creating a sealed cabin with a conventional companionway door, providing full 6-foot-3-inch standing headroom throughout the saloon and hulls.
Structurally, the 900 is built with solid, double-thick fiberglass below the waterline and a cored deck, bypassing the light-displacement, flexible build styles of modern high-performance multihulls. This construction technique yields an 8,000-pound dry displacement on a 30-foot frame, giving her a reassuringly solid, non-flexing feel in a seaway. While contemporary competitors like the Gemini 105MC or Prout Quest 31 targeted lighter, faster hull lines, the Catalac 900 doubled down on heavy weather resilience, wide-flaring chines, and a solid GRP foredeck instead of a trampoline.
The interior joinery reflects this robust English heritage, featuring high-quality woodwork and a highly functional split-hull layout. The port hull is dedicated to a spacious, linear galley-down layout. The starboard hull houses a dedicated navigation station amidships and a surprisingly large head with a shower compartment located in the aft section. Forward over the bridge deck, the boat offers separate double and single cabins. This makes the boat highly comfortable for a couple or a small family, while still possessing the technical capacity to sleep up to seven when utilizing the convertible saloon settee.
Variations & Configurations
Because Blue Water Catalacs sold several 900 hulls as partially completed "kits" or owner-finished projects, the interior configurations and helm setups can vary significantly on the secondary market. The factory layout was designed with a fully enclosed internal helm station within the pilot house, allowing the operator to steer from a warm, dry environment during inclement weather. However, some owners opted to build their boats without the internal helm, relying solely on an aft cockpit helm. Other vessels feature a dual-helm configuration with controls both inside the saloon and in the cockpit.
The propulsion system is another area where the Catalac 900 departed significantly from its predecessor. The older 9M models were typically fitted with a single centrally-placed steered outboard, or twin shaft-driven inboard diesels. The Catalac 900 modernized this setup by standardizing twin diesel engines paired with saildrive transmissions, typically featuring 10-hp to 14-hp units from Yanmar (e.g., the 2YM series), Volvo, or Nanni. Because the saildrives allowed the engines to be mounted much further aft in the hulls, the interior volume was dramatically improved: the port aft single quarter-berth was expanded, and a cavernous lazarette was created on the starboard side.
Sailing Performance & Handling
With a moderate Sail Area to Displacement (SA/Disp) ratio of 16.8, the Catalac 900 has a conservative masthead sloop rig designed for reliability rather than light-wind performance. This matches its Displacement to Length (Disp/LWL) ratio of 165.69, which places it firmly in the medium-heavy displacement category for multihulls of this length. Under sail, she feels exceptionally stable and predictable. The Comfort Ratio of 13.02 and a low Capsize Screening Ratio of 2.78 point to a vessel that resists rapid, violent motions in a seaway.
The underbody, originally drafted by naval architect John Winterbotham based on the hull lines of the WWII-era Sunderland flying boat, features a pronounced rocker profile, hard-chine sections, and widely flaring topsides. This design possesses a unique safety characteristic: under extreme wind loads, the hulls are designed to slip sideways (skid to leeward) rather than dig in and lift the windward hull.
However, this hull shape dictates several handling realities. Because the hulls lack deep daggers or high-aspect keels, the 900 does not point highly upwind. In heavy air, the windage of the raised pilothouse increases leeway. If an operator attempts to pinch the boat too close to the wind, forward momentum drops, and the vessel can easily end up in irons. The accepted sailing strategy is to fall off several points, allowing her to gain speed and reduce the drag of the rudders. Additionally, because the hull flare provides immense load-carrying capacity without showing visual signs of squatting, owners frequently overload the boat, which further degrades her pointing ability and speed.
Under power, the twin-engine configuration and aft saildrives make the 900 incredibly nimble in tight quarters. By locking the rudders dead ahead and steering solely with the twin engine throttles, the boat can spin 360 degrees within its own length.
Market Snapshot & Economics
Given that only about 20 to 26 units were produced, the Catalac 900 is a rare find on the global brokerage market. It commands a noticeable price premium over the much more common 9M (of which 255 were built), owing to its modern aesthetics, standing headroom, and twin saildrive diesel configuration.
Prospective buyers must approach any listing with a discerning eye for build pedigree. Because some boats were completed by amateur owners from factory kits, the wiring, plumbing, and cabinetry finishes can range from professional-grade luxury to questionable DIY attempts. Consequently, a comprehensive professional survey is mandatory, with special attention paid to any owner-installed auxiliary systems.
Known Issues & Triage
While the Catalac 900 is structurally overbuilt, it is not immune to age-related maintenance items:
- Perspex Window Leaks: The long, tinted Perspex side windows that give the 900 its modern, sleek look are glued and sealed directly to the fiberglass superstructure. Over decades, thermal expansion and UV exposure can degrade the adhesive sealant, leading to persistent leaks. Remedying this requires completely removing the Perspex panels, cleaning the mating surfaces down to the gelcoat, and re-bedding them with high-grade marine polyurethanes (such as Dow Corning 795 or SikaFlex 295 UV).
- Saildrive Diaphragms: The twin saildrive installations rely on thick rubber sealing diaphragms to keep the ocean out of the engine compartments. Manufacturers generally recommend replacing these diaphragms every seven to ten years. Prospective owners must verify the age of these seals, as replacement requires pulling the boat and splitting the engines from the saildrive units.
- Engine Cooling and Silt: For boats operating in shallow, silty waters, the raw-water intakes on the saildrives can ingest fine mud. This abrasive silt prematurely wears out raw-water pump impellers and seals. Left unchecked, leaking pump seals can drip saltwater directly onto nearby oil lines or engine mounts, accelerating corrosion.
Modernization & Upgrades
Due to the age of the original machinery, many owners are updating the propulsion and electrical platforms on these boats. Replacing older 10-hp Volvo or Yanmar diesels with modern 14-hp to 15-hp twin diesels is common.
Because the Catalac 900 features a wide, solid GRP cabin top and a flat, solid foredeck, it is an ideal candidate for substantial solar arrays. Veteran owners regularly mount heavy-duty stainless-steel arch gantries over the stern to support 500 watts or more of solar panels without affecting the boat's stability. This solar power is frequently paired with a conversion to Lithium Iron Phosphate (LiFePO4) house battery banks, which fit easily into the deep lazarettes or the massive storage spaces under the forward bridge deck berths.
The Verdict
The Catalac 900 is an incredibly robust, safe, and surprisingly liveable "pocket" catamaran. It successfully remedies the headroom and helm exposure complaints of the legendary 9M, packaging them into a modern, low-maintenance aesthetic. While it will never win races or point like a monohull, its legendary "battleship" build quality makes it an exceptional choice for coastal cruising or sensible offshore passages.
Pros:
- True 6'3" standing headroom throughout the saloon and both hulls
- Fully enclosed, weather-tight pilothouse helm station for comfortable cold-weather cruising
- Twin diesel engines with saildrives offer superb close-quarters maneuvering and increased interior volume
- Robust, solid fiberglass hull construction designed to handle punishing North Sea conditions
- Unique hull flare provides excellent safety by slipping to leeward rather than lifting a hull
Cons:
- Poor upwind pointing performance due to low-aspect hulls and high cabin windage
- Extremely rare on the brokerage market with only 20 to 26 units built
- Sailing performance is highly sensitive to overloading, which is easy to do given the boat's massive interior storage capacity
- Varying build and finish quality among owner-finished kit versions
