Design Brief & Intent 4
The 725 was conceived to deliver effortless, high-performance bluewater passage-making for an owner-operator who might occasionally run the yacht with a professional captain and mate. Humphreys Yacht Design focused heavily on optimizing the hull shape and weight distribution, resulting in a lighter and stiffer hull than its predecessor without compromising structural integrity. The yacht was designed to handle severe ocean conditions while remaining manageable by a shorthanded crew, thanks to a high degree of push-button hydraulic sail control.
Below decks, the interior showcases the hand-crafted joinery for which the builder is renowned, utilizing solid timber, precise shadow-gap detailing, and highly insulated bulkheads. Hull 01 was finished in contemporary horizontal-grain quarter-sawn American white oak, while later hulls feature traditional warm, semi-gloss teak. The defining feature of the living space is the deck saloon, where the triple curved glass vertical seascape windows flood the cabin with light, offering guests an unparalleled water-level vista while seated at the dining table.
Variations & Configurations
While sharing the same hull lines, each of the three 725 hulls was highly customized. For underwater profiles, the standard draft features a High Performance Bulb keel drawing 2.95 meters (9 feet, 8 inches) to maximize upwind tracking and righting moment. A shoal-draft bulb option drawing 2.34 meters (7 feet, 8 inches) was also offered for owners looking to cruise thinner waters like the Bahamas.
Rig configurations vary significantly among the hulls:
- Hull 01 (Intrepid) was built as a high-performance sloop featuring a carbon fiber mast and a traditional slab-reefed mainsail with a park-avenue boom, maximizing sail shape control.
- Hull 02 (Rosinha) was built with a performance cutter rig, carbon mast, and a carbon fiber V-boom for a fully battened mainsail, providing a balance of raw speed and easy shorthanded handling.
- Hull 03 (Isabel, originally On Liberty) was optimized for push-button cruising with a hydraulic in-mast furling cutter rig and a painted aluminum spar.
Interior layouts generally adhere to an owner-aft configuration. The master stateroom sits furthest aft with a private companionway, a centerline king berth, and a massive en-suite head with a separate shower stall. Forward of the master cabin, a corridor accesses a double guest VIP cabin to port and an upper-and-lower bunk cabin to starboard. Forward of the saloon and the expansive, longitudinal galley, the space can be configured either as two en-suite crew cabins or as a secondary luxury VIP guest suite.
Sailing Performance & Handling 4
Displacing 51,500 kilograms (113,538 pounds) at half-load and carrying 310 square meters (3,337 square feet) of sail area under a 150% foretriangle, the 725 boasts a potent Sail Area to Displacement ratio of 23.17. On the water, this translates to lively light-air performance that is uncharacteristic of traditional heavy-displacement cruisers. The yacht easily sustains nine to ten knots of boat speed on a reach in moderate breezes of 12 to 14 knots.
With a long waterline length of 19.75 meters (64 feet, 9 inches), the 725 displays a moderate Displacement to Length ratio 4. Her hull form carries its beam well aft to provide excellent initial stability and to flatten the boat's sailing attitude as she heels. At the helm, the twin wheels offer a direct, highly balanced mechanical steering feel. The deep, high-aspect-ratio rudder is fully hung on a robust structural skeg, which not only protects the steering gear from collision damage but also provides outstanding directional tracking in a following sea. The hull remains highly docile under autopilot control even when hard-pressed in large ocean swells.
Market Snapshot & Economics
The Oyster 725 occupies an elite, highly insulated niche in the brokerage market. Because only three hulls exist worldwide, the model is exceedingly scarce. It represents an attractive value proposition for the buyer who desires superyacht-level finishes and performance but wants to avoid the geometric escalation of berthing fees, regulatory compliance, and the absolute requirement for a large, full-time professional crew associated with vessels over 80 feet.
Refit economics for the 725 align with its pocket-superyacht status. Owners must budget for professional-grade systems maintenance. Routine shipyard work—such as servicing the complex central Lewmar hydraulic package, overhauling the robust 212-horsepower Cummins QSB5.9 main engine, and completing the mandatory five-year pull-and-inspect rod rigging service—requires substantial capital. However, because the hull laminates utilize exceptionally durable composite engineering, structural depreciation is minimal, and the yacht retains its residual value remarkably well compared to mass-produced vessels of similar size 4.
Known Issues & Triage 3
With only three hulls constructed under rigorous shipyard supervision, the 725 is free of common, systemic manufacturing defects. However, several critical systems require rigorous inspection during any pre-purchase survey:
- The Keel Structure: During the production run of the 725, the builder faced a highly publicized keel structural failure on an Oyster 825 (Polina Star III). Although the 725 uses a thoroughly engineered integrated keel structure with solid laminate reinforcements modeled via Finite Element Analysis, any surveyor should conduct non-destructive ultrasound testing around the keel-to-hull joint and the surrounding internal bilge structure to ensure the laminates are entirely sound 8.
- Seascape Window Bonds: The vertical curved glass seascape windows are chemically bonded into recessed hull pockets. Intense tropical UV and natural hull flexing can stress the polyurethane adhesive over time. Triage must focus on checking the margins for signs of seal degradation, delamination, or interior weeping.
- Rod Rigging Fatigue: Solid rod rigging has a strict operational lifespan of approximately five to six years or 40,000 miles before requiring complete disassembly, dye-penetrant testing of the cold-headed terminals, and replacement of compromised components. Prospective buyers must verify the date of the last rigging service to avoid immediate six-figure maintenance bills.
- Hydraulic System Wear: The central Lewmar hydraulic power pack controls the sail furlers, windlasses, and bow and stern thrusters. Inspect all hydraulic hoses for dry-rot, trace the system for micro-leaks, and test the power-take-off (PTO) pumps on the generator and main engine under load to check for pressure drops.
Modernization & Upgrades 6
Recent refits of the 725 hulls, especially those preparing for multi-year circumnavigations, have focused on self-sufficiency and reducing fossil fuel consumption.
- Silent Power Conversion: Owners have successfully replaced traditional, heavy AGM batteries with massive 24V Lithium-ion (LiFePO4) banks of up to 2,400Ah. When paired with parallel Mastervolt inverters (sometimes totaling up to 17,000 watts of continuous AC capacity), the system can easily run high-draw AC loads, such as the watermaker and full-boat air conditioning, directly off the battery bank overnight, allowing the yacht to run silently at anchor without starting the generator.
- Composite Solar Bimini: To feed these high-capacity battery banks, owners have retrofitted custom carbon-fiber hard-top biminis (often built by specialist composite yards like BMComposites). These hard-tops support up to 13 square meters of walk-on, high-efficiency solar panels, generating over 2,100 Watts of green energy.
- Alternator & Charging Upgrades: To supplement solar power, owners often swap the stock engine alternator for a continuous-duty, high-output 320-amp alternator governed by an external smart regulator, drastically reducing generator runtime when under motor.
- Downwind Sailing Gear: Retrofitting a custom carbon fiber bowsprit has become a standard upgrade. This allows the deployment of modern, top-down furling asymmetric spinnakers and Code Zero sails, providing sparkling light-air performance downwind and minimizing diesel engine hours during long passages.
The Verdict 2
The Oyster 725 is a masterclass in modern, semi-custom bluewater yacht design. It stands out as one of the most structurally reliable, visually striking, and comfortable passagemakers of its generation, offering true superyacht luxury in a package that can still be successfully managed by an active couple. While its extreme rarity and complex systems demand substantial, professional-grade maintenance budgets, the 725 rewards its owners with legendary offshore capability, whisper-quiet living at anchor when modernized, and a level of exclusivity that few other production yachts can match.
Pros
- Outstanding offshore performance, yielding fast, comfortable, and predictable passage times in a wide range of sea states.
- Extreme exclusivity and high pedigree, with only three hulls built, ensuring high residual value and superyacht prestige 3.
- Ingenious interior layout providing absolute privacy for the owner aft while allowing for separate, fully equipped crew quarters forward.
- Massive structural strength and a highly protected, skeg-hung rudder for peace of mind when cruising remote, debris-strewn oceans.
- Outstanding natural light and panoramic views in the saloon courtesy of the iconic vertical curved-glass seascape windows.
Cons
- High complexity of centralized hydraulic and electrical systems, requiring specialized knowledge and substantial maintenance budgets.
- Solid rod rigging requires costly, mandatory disassembly and dye-penetrant testing every five to six years.
- Finding one of the three hulls on the brokerage market is exceptionally difficult due to their extreme scarcity 3.
- Standard 2.95-meter draft limits access to shallow-water anchorages and marinas unless the rare shoal-draft version is found.
