Design Brief & Intent
The primary mandate of the Impala 28 was to deliver fast, tactical, and level-rating offshore racing at an accessible price point. At the time of its launch, it was positioned as a direct, high-performance competitor to heavier-displacement pocket cruisers like the Contessa 28. While the Contessa favored heavy layup schedules and ultimate motion comfort, David Thomas prioritized weight optimization, an easily driven hull form, and responsive handling.
This optimization is clearly reflected in the vessel's interior. The accommodation is unashamedly minimalist, eschewing heavy joinery and plush cruising comforts to save weight. Headroom is restricted, and the layout centers around GRP-molded components rather than structural teak or mahogany cabinetry. The standard layout features a small V-berth in the forepeak (often utilized primarily for sail storage), a marine head positioned forward of the main bulkhead, and two straight settee berths in the saloon that double as sea berths. Two large quarter berths run aft under the cockpit, bringing the total sleeping capacity to six—ideal for a racing crew but cramped for family cruising. A rudimentary galley with a simple stove and a slide-out chart table completes a cabin built for functional offshore passage-making rather than liveaboard comfort.
Variations & Configurations
Over its production life and subsequent decades of class development, the Impala 28 has seen minor structural evolutions. The most significant architectural change concerns propulsion. Early hulls were delivered with an innovative, faired outboard motor well built into the cockpit floor. This system allowed a small outboard to be lowered into the water or pulled up and sealed with a flush-fitting hull plate to eliminate racing drag. In 1988, the Impala 28 Class Association modified class rules to permit the installation of an inboard diesel. The designated engine was the 9-horsepower Yanmar 1GM (later the 1GM10), a compact single-cylinder unit that fits neatly under the companionway steps. To maintain true one-design parity, class rules mandate that outboard-powered boats carry specific corrector weights (often around 250 lbs of lead) to balance out the drag and center of gravity differences of the inboard models.
The steering configuration underwent a major factory-approved redesign. The original rudder blade had a relatively shallow draft and a low-aspect-ratio profile, which made the boat prone to losing grip and broaching when hard-pressed downwind in a blow. David Thomas subsequently designed a deeper, higher-aspect-ratio "Mark II" rudder. This modification significantly improved directional stability and helm control, and it has since been adopted by virtually the entire active racing fleet.
Sailing Performance & Handling
The sailing characteristics of the Impala 28 are dictated by its athletic physical ratios. Boasting a light-displacement-to-length (Disp/LWL) ratio of 154.33 and an overall displacement of just 4,300 lbs, the hull is incredibly light and easily driven. In light air, the boat is exceptionally lively, accelerating out of tacks with minimal drag. Under a fractional sloop rig with a high-aspect mainsail and a non-overlapping blade jib, the sail-area-to-displacement (SA/Disp) ratio of 20.27 places the Impala firmly in the high-performance category for a 1970s design.
Downwind, the boat's flat aft sections and light weight enable it to surf and occasionally plane in flat water when driven hard under its large symmetrical spinnaker. However, this agility requires active crew work and helming precision. With a capsize screening ratio of 2.28, the boat has a relatively wide beam (9 feet 4 inches) relative to its light displacement, meaning it relies heavily on form stability and crew weight on the rail to remain flat. If allowed to heel excessively, the hull shape loses efficiency and places a heavy load on the rudder. The comfort ratio of 13.94 indicates that the motion in a seaway is quick, stiff, and wet. It is not designed to slice through heavy head seas with the passive ease of a heavy-displacement cruiser, but rather to be actively trimmed, using backstay and shroud tension to flatten the sails and keep the boat on its feet.
Known Issues & Triage
Prospective owners of an Impala 28 must evaluate several age-related structural areas common to GRP production boats of this era:
- Keel Interface and Cast Iron Keel Corrosion: The deep 5-foot 6-inch fin keel is cast iron. Under years of accumulated antifoul paint, deep-seated rust pockets can develop. Owners routinely report the need to drop the keel, sandblast the iron to bare metal, treat it with protective epoxy barrier coats, and fair the keel-to-hull joint. The GRP keel box surrounding the top of the keel is also prone to localized stress cracking and requires careful inspection.
- Deck Core Softness: The decks are constructed using a balsa-core sandwich laminate. Over forty-plus years of hard racing, original deck hardware (such as sheet tracks, chainplates, and winches) can leak, allowing water to penetrate the balsa core. Finding soft, delaminated spots on the deck is common, requiring localized core replacement and re-bedding of all deck fittings.
- Outboard Well Integrity: On boats retaining the outboard-well configuration, the structural shelf and surrounding GRP moldings can suffer from stress cracking, fatigue, and leaks around the fairing plate. Rebuilding and resealing this well is a common mid-life triage requirement.
- Original Rudder Delamination: Original Mark I rudders are highly prone to water ingress, leading to internal foam rot and delamination around the stainless steel stock. Upgrading to a custom-built Mark II rudder is the standard structural fix.
Modernization & Upgrades
As a highly active one-design class, the modernization of the Impala 28 is closely managed by class rules to prevent "checkbook racing" while keeping the boats seaworthy and reliable.
- Rigging and Deck Hardware: Modern owners have widely retrofitted original deck layouts with high-load Harken blocks, Spinlock halyard clutches, and high-tensile Dyneema running rigging to allow for fast, reliable sail adjustments under load.
- Sailcloth Upgrades: While early class rules heavily restricted materials, modern regulations permit high-performance laminate sails (such as aramid and carbon sport laminates) for one-design racing, which dramatically improves shape retention and upwind performance.
- Drivetrain Replacements: Aging Yanmar 1GM engines are commonly replaced with the modern Yanmar 1GM10. Because the engine space is highly restricted, alternative powerplants are difficult to fit without major structural alteration of the companionway steps.
The Verdict
The Thomas Impala 28 remains an exceptional, low-cost entry point into highly competitive one-design racing and spirited coastal cruising. It is a sailor’s boat—rewarding active trim, physical fitness, and tactical intelligence over passive comfort. While it lacks the amenities, standing headroom, and heavy-weather dampening of a dedicated cruising yacht, its legendary build quality and thrilling sailing characteristics have secured its status as a timeless British classic.
Pros
- Exceptional light-wind acceleration and genuine downwind surfing capability.
- Highly active, supportive, and tightly regulated one-design class association.
- Very affordable entry and maintenance costs relative to modern sportsboats.
- Responsive, dinghy-like handling at the helm when retrofitted with the Mark II rudder.
Cons
- Stark, cramped interior with limited headroom and minimal cruising amenities.
- Lively, wet, and motion-heavy ride in chop due to low displacement-to-length ratio.
- Susceptible to balsa core rot in the deck and cast-iron keel corrosion.
- Requires a physically active, coordinated crew to sail to its full potential.
