Exlex X – Experimental.

In his seaside workshop in Västervik, Sweden, legendary 87-year-old solo ocean voyager and naval architect Sven Yrvind of Sven Yrvind has introduced a pivotal developmental phase in his micro-cruiser project. Rather than rushing forward with the full composite construction of his 5.6-meter high-latitude ocean cruiser, Yrvind has temporarily unscrewed and set aside his hull molds to build Exlex X—a 4.2-meter (13.8-foot) experimental plywood sailing prototype designed for a rigorous North Atlantic shakedown voyage.

Inspired by the minimalist naval architecture of Matt Layden’s Paradox design, Exlex X serves as an empirical floating laboratory. Yrvind’s decision is rooted in a fundamental seamanship conviction: complex hydrodynamic and survival innovations must be rigorously proven under open-ocean sea conditions rather than assumed through desk calculations or indoor theory alone.

The Three Foundational Innovations of Exlex X

The primary purpose of the Exlex X prototype is to validate three interrelated systems that diverge significantly from conventional small-craft naval architecture:

• The Dual-Blade Plow Rudder: Mounted at the stern, this system features two hydrodynamic blades fixed at a reciprocal five- to seven-degree outward angle. When running before heavy downwind seas and storm gales, deploying both blades creates symmetrical directional drag that acts like an agricultural plow, steadying the vessel on course. For directional steering, raising or lowering individual blades modulates lateral resistance without rotating on a vertical pintle. Because no components protrude beneath the bottom of the hull, the vessel can slide into shallow estuaries, sit flat on a road trailer, and presents zero appendages for curious orcas to damage.
• Movable Transverse Ballast Tunnel: Beneath the central 1.8-meter sleeping bunk, Yrvind engineered an internal transverse conduit containing four individual lead weights weighing 14 to 15 kilograms (31 to 33 pounds) each. Rigged with low-friction haul lines leading to side-deck jam cleats, the skipper can manually slide the lead blocks to windward when tacking, providing substantial active righting moment without carrying excessive static displacement. For trailering or road transport, each weight can be removed independently by hand.
• Capsize-Proof Surge Chamber Ventilation: Fresh airflow inside a sealed micro-cruiser during oceanic gales is a matter of survival. Yrvind’s surge chamber utilizes an internal baffled labyrinth that separates ambient air from green water. Even in the event of a catastrophic 360-degree knockdown, pitchpole, or extended inversion, gravity channels trap and divert incoming water out through bottom scupper drains while maintaining continuous air circulation into the living cabin.

Harbor Maneuvering and the Two-Masted Rig

To complement the plow rudder at sea, Yrvind integrates a traditional long steering oar for harbor maneuvers, tight marina quarters, and navigating breaking surf. As observed in lifeboats and surf rescue craft, conventional rudders lose waterflow and stall when an overtaking wave breaks over the transom. A heavy sweep oar, by contrast, operates independently of boat speed, delivering reliable leverage in extreme localized turbulence.

In addition, Yrvind has simplified the sailplan from his earlier three-masted lugger concept to a clean two-masted unstayed configuration. Eliminating one mast reduces windage, simplifies standing rigging, and lightens the forward deck, while allowing balanced self-steering across a wide variety of wind angles.

Interior Ergonomics and Ocean Philosophy

Despite measuring only 4.2 meters in length overall, the interior layout of Exlex X is organized around functional watertight compartments separated by two structural bulkheads. The arrangement includes an aft working bay for navigation and watchkeeping, a forward working and storage bay, a comfortable 1.8-meter sleeping berth, and a dining station flanked by integrated side sinks for cooking and maintenance.

Reflecting on the rigorous testing required before attempting high-latitude voyaging toward the Southern Ocean and New Zealand, Yrvind cited the famous aphorism of Prussian Field Marshal Helmuth von Moltke: "No battle plan survives first contact with the enemy." In maritime voyaging, the ocean is the ultimate testing ground, and building a sacrificial, highly adaptable plywood test hull ensures that every structural refinement is earned through salt water experience.

Exlex X Specifications and Innovations Overview

The engineering parameters and specialized subsystems of Exlex X are summarized in the technical log below:

Frequently Asked Questions