Design Brief & Intent
The foundational mission of the MRCB 37 was to offer cruising sailors the ultimate freedom: the ability to cover vast distances under sail when the wind favored, and to outrun storms or reach port before dark at speeds matching a dedicated powerboat. This put the MRCB 37 in a category far removed from the slow, heavy motorsailers of its era, as well as the compromised trailer-sailers of later decades. To achieve this, Anderson and Baker designed a hull that could physically adapt to its operational mode. The boat's design brief hinged on a system of hydraulic "variable hull geometry" flaps at the transom. Under sail, these flaps were retracted, allowing the hull to maintain a classic curved rocker that easily released water and minimized drag. Under power, hydraulic actuators extended these flaps downward, flattening the stern buttocks to create a planing surface that prevented the transom from squatting under heavy throttle.
The interior of the MRCB 37 reflected its high-end British pedigree. Built for long-term cruising comfort, the cabin arrangement featured seven berths, a functional galley, and a head, all finished in rich timber joinery. Unlike the sparse, utilitarian interiors of racing yachts of the time, the MRCB 37 maintained a warm, traditional aesthetic. Furthermore, the deck was constructed as a balsa-cored fiberglass sandwich. This engineering choice was specifically intended to improve the indoor climate; the double-hull construction served as an effective thermal barrier, insulating the cabin against cold water and drastically reducing the condensation issues that plagued solid-fiberglass yachts in northern climates.
Variations & Configurations
Given its highly specialized nature and micro-production run, the MRCB 37 did not feature a wide array of production-line options, but its standard configuration was packed with unique design details. The rig was a fractional sloop, a setup that prioritized a highly manageable sail plan. By utilizing a smaller, self-tacking headsail, the designers ensured that short-handed crews could easily handle the vessel under canvas.
The keel configuration was an innovative stub-and-centerboard arrangement, often described as a wing-keel hybrid. This design incorporated a fixed shallow wing stub that housed a heavy, retractable centerboard. With the centerboard fully retracted, the boat drew an astonishingly shallow draft of under two feet, allowing it to enter restricted channels, navigate canals, and take the ground in drying harbors. When fully lowered, the centerboard extended the draft to just over seven feet, providing the necessary lateral resistance and lift required for efficient windward sailing.
The defining mechanical feature was its propulsion system. The boat was equipped with a 165-horsepower Volvo Penta AQD40 turbocharged diesel engine mated to a custom retractable outdrive. When sailing, the drive leg was raised electronically using a hydraulic pump, sealing the hull aperture with flush-fitting doors to eliminate drag. Under power, the drive leg was lowered into the stream, deploying counter-rotating propellers designed to efficiently transfer the engine's massive torque into forward thrust.
Sailing Performance & Handling
On the water, the MRCB 37 is a study in dual personalities, and its calculated design ratios explain exactly how it behaves in both of its operating modes. Under sail, the boat has a displacement of 9,408 pounds, which is exceptionally light for a 37-foot cruising yacht. Combined with a displacement-to-length ratio of 118.7, the vessel is categorized alongside ultra-light displacement racers. This light weight enables rapid acceleration and allows the hull to react quickly to gusts. However, with a sail-area-to-displacement ratio of 15.08, the sail plan is relatively conservative. This keeps the boat easily manageable and prevents it from becoming overpowered too quickly, though it relies on off-wind sails like gennakers or code zeros to maintain high speeds in light air.
The boat's stability characteristics are dictated by its ballast-to-displacement ratio of 23.81 percent. This relatively low ballast ratio means the boat relies heavily on form stability derived from its generous 12.08-foot beam. Consequently, the capsize screening ratio stands at 2.29, indicating a hull form that is wide and stable in moderate conditions but requires active seamanship and timely reefing in heavy weather to manage heel. In a seaway, the comfort ratio of 15.45 translates to a lively, motion-rich ride. Rather than plowing through waves like a heavy, full-keeled cruiser, the light-displacement hull tends to ride over them, a sensation more closely aligned with modern performance multihulls or light racer-cruisers.
The real magic occurs when the sails are furled and the engine is engaged. Once the Volvo Penta diesel is fired up, the outdrive lowered, and the transom flaps deployed, the boat transitions from a displacement sailing hull into a planing vessel. The 165-horsepower engine, aided by the flattened stern geometry, successfully lifts the 37-footer onto a plane, achieving top speeds of nearly 18 to 20 knots. This transition is smooth, and the boat runs with surprisingly little bow-rise thanks to the lift generated by the hydraulic stern flaps.
Market Snapshot & Economics
Finding an MRCB 37 on the brokerage market today is an exceedingly rare event. With only a handful of hulls ever produced, these boats are essentially collector’s items, trading hands through private networks or specialized listings rather than standard high-volume brokerage channels. When they do appear, they do not follow standard valuation curves; instead, their value is heavily dependent on the operational status of their highly complex mechanical and hydraulic systems.
For a prospective buyer, the economics of owning an MRCB 37 are Greatly linked to refit and preservation costs. While a standard 37-foot production sailboat of the 1980s can be maintained with off-the-shelf parts, the MRCB 37 requires specialized mechanical support. Rebuilding the custom hydraulic systems that actuate the planing flaps and the retractable outdrive leg can easily exceed the cost of standard auxiliary engine replacements. For this reason, the boat appeals to a very specific niche: experienced sailors with an appreciation for classic British marine innovation and a willingness to maintain a complex hybrid drivetrain.
Known Issues & Triage
The primary technical vulnerability of the MRCB 37 lies within its greatest innovation: the retractable propulsion and hull-shaping mechanisms. The electronic-hydraulic pumps and rams responsible for raising the Volvo Penta drive leg and extending the transom flaps operate in a highly corrosive marine environment. Over decades, seal degradation can lead to hydraulic fluid leaks or, worse, saltwater intrusion into the hydraulic actuators. Regular pressure testing of the hydraulic circuits, replacing old hoses with modern synthetic equivalents, and meticulously maintaining sacrificial anodes on the drive leg are mandatory triage routines.
The retractable drive system also relies on an underwater hull-aperture door system. If these doors fail to close tightly when the drive is retracted, they can create significant drag and turbulence under sail, or trap marine growth and debris. Owners must inspect the alignment of these doors and the integrity of their mechanical linkages during routine haul-outs.
Structurally, the balsa-cored sandwich deck is a known area requiring careful monitoring. Over forty years of service, moisture can compromise the deck fittings, stanchion bases, and chainplates. If water penetrates the fiberglass skin and reaches the balsa core, rot can spread, leading to soft spots and compromised structural integrity. Triage involves using a moisture meter to map out any wet areas, followed by localized recoring with modern closed-cell foam or marine plywood, and rebedding all deck hardware with high-grade marine sealants.
The Verdict
The MRCB 37 remains one of the most intriguing "what-if" designs in modern yachting history. By merging the work of a brilliant naval architect with the fiberglass building expertise of Halmatic, MRCB Developments created a boat that truly pushed the boundaries of hybrid marine propulsion. While it never achieved widespread commercial success due to its high production costs and mechanical complexity, it proved that a sailboat could plane at nearly 20 knots without completely sacrificing its dignity under canvas. For the modern enthusiast, it is a fascinating piece of floating history that offers a unique combination of shallow-draft versatility, high-speed motoring, and spirited sailing.
- Revolutionary variable hull geometry allows for genuine planing speeds under power without compromising the hull shape under sail.
- Stub-and-centerboard keel design offers an incredibly shallow draft of under two feet with the board up, ideal for canals and shallow anchorages.
- Lightweight construction and a light displacement-to-length ratio deliver responsive, lively performance under sail.
- Highly insulated balsa-cored sandwich deck construction prevents cabin condensation in colder climates.
- High mechanical complexity involving custom hydraulics for the outdrive and stern flaps, making maintenance demanding and expensive.
- Low ballast-to-displacement ratio and high capsize screening ratio make the boat less suitable for extreme offshore passages.
- Extremely rare vessel with only a handful of hulls built, making parts sourcing and sistership advice difficult to find.
- Balsa-cored decks are susceptible to moisture intrusion and rot if deck hardware is not meticulously maintained.
