Seastream 43 Information, Review, Specs

Sailing Performance & Handling

The Seastream 43 is a heavy-displacement cruiser with a Displacement/Length (D/L) ratio of approximately 316, placing it firmly in the "heavy" category. This mass, combined with a ballast-to-displacement ratio of nearly 36%, results in a remarkably stable and "seakindly" motion. According to technical data hosted by the Seastream Owners Association, the boat exhibits a Comfort Ratio of 37.9, indicating that its motion in a seaway is predictable and less fatiguing for the crew than lighter, modern production boats.

While early models were frequently rigged as ketches to break up the sail area for short-handed crews, later versions and the Mark II often featured a taller cutter rig. This transition was noted in editorial retrospectives by Yachting Monthly as a significant improvement to the boat’s light-air performance and windward ability. The hull features a long fin keel and a massive skeg-hung rudder, which provides excellent tracking and protection for the steering gear. However, the heavy displacement and conservative sail plan mean that the Seastream 43 is not a "light air" performer; it typically requires 12–15 knots of breeze to truly come alive. Under power, most units are equipped with reliable 80hp engines, such as the Mercedes OM314 or Perkins 4.236, providing the thrust necessary to maintain speed against head seas.

Interior Comfort & Variations

The defining characteristic of the Seastream 43 is its deck saloon, which offers 360-degree visibility from a raised U-shaped dinette. This layout allows the crew to monitor the horizon and navigate from the warmth of the interior—a feature often supplemented by an internal conning station or a secondary throttle and autopilot control. The interior is typically finished in high-quality teak or cherry, reflecting its heritage from yards like Rival Yachts.

The standard accommodation plan includes three separate cabins and two heads. The master suite is located aft, benefitting from the boat's significant beam. In the Mark I, the cockpit was deeper and more central, which slightly encroached on aft cabin headroom. The Mark II addressed this by moving the cockpit further aft and raising the coachroof slightly, creating a more voluminous owner's cabin with improved ventilation. A midships cabin usually features twin bunks, while the forward V-berth serves as a guest cabin with ensuite access to the forward head. The galley is located "down" from the saloon in early models but remains well-ventilated and secure for cooking at sea.

Popular Mentions & Media

The Seastream 43’s reputation for extreme seaworthiness is well-documented in technical circles. A notable entry in the Victor Shane Drag Device Data Base details the experience of the Seastream 43 Shadowfax, which successfully deployed a Jordan Series Drogue during a single-handed passage from the Canary Islands to the Azores. The vessel weathered 45-knot winds and breaking seas of up to 23 feet, with the report highlighting the hull's structural integrity and the overbuilt nature of its deck hardware.

Known Issues & Buyer’s Checklist

Prospective buyers should focus on the specific construction methods used during the 1980s and 90s:

• Deck Core Integrity: The decks are a balsa-sandwich construction. Like all boats of this era, moisture ingress around stanchion bases, windlasses, or the large deck saloon windows can lead to core delamination. A professional moisture meter reading is essential.
• Window Seals: The large toughened-glass windows of the deck saloon are a hallmark of the design but are prone to leaking if the original bedding compound has hardened. Replacing these seals is a labor-intensive task.
• Rudder Bearings and Skeg: Given the age of these vessels, the top rudder bearings should be inspected for play. The skeg-hung rudder is extremely strong, but the connection points require periodic verification.
• Osmosis: While the hulls were built to Lloyds 100-A-1 requirements, some earlier hulls have reported osmotic blistering. Many existing examples have undergone preventative epoxy treatments, which should be verified in the vessel's service history.
• Kevlar Layup: It is worth noting that some hulls incorporated Kevlar in the layup for increased impact resistance; buyers should check the original build specifications to confirm if their specific hull features this reinforcement.

Community & Resources

The primary hub for technical support and historical data is the Seastream Owners Association. This resource provides access to original Ian Anderson drawings, fleet lists, and technical advice shared by a global community of owners who actively use these boats for high-latitude and transoceanic cruising.

The Verdict

The Seastream 43 remains one of the most capable mid-sized bluewater cruisers ever produced in the UK, offering a level of interior comfort and safety that rivals more expensive counterparts like Discovery or Hallberg-Rassy.

Pros:

• Exceptional "all-weather" protection via the deck saloon.
• Heavy-duty construction with high ballast-to-displacement ratio.
• Spacious three-cabin layout suitable for liveaboard families.
• Predictable, seakindly motion in heavy weather.

Cons:

• Modest performance in light winds (under 10 knots).
• Large window areas can lead to heat gain in tropical climates if not properly shaded.
• Deep draft and heavy displacement limit options in shallow coastal cruising areas.