R & D Flexible Shaft Coupling f/5" B/W, Hurth - 13HP/100RPM Capacity

The R & D Flexible Shaft Coupling for 5" B/W Hurth marine engines delivers reliable power transmission with a 13 HP / 100 RPM capacity rating. This flexible shaft coupling is engineered to absorb misalignment and vibration between the engine and propeller shaft—two critical sources of wear in modern marine powerplants. The contoured polyurethane flexible disc is molded to withstand the rigorous demands of saltwater and freshwater boating while maintaining precise torque delivery.

The coupling's design addresses real-world marine conditions: boat hull flexing under load, engine movement on rubber vibration isolation mounts, and temporary shaft misalignment from dynamic operating conditions all translate to stress that standard rigid couplings cannot handle. The flexible disc's contoured geometry provides bolt head clearance and allows free flexing without binding. Forward thrust loads are managed through compression on the disc itself, reducing shock loads transmitted to the gearbox and engine mounting system. At 3.8 lbs with compact 8" × 4" × 8" dimensions, this coupling integrates cleanly into tight engine compartments.

This coupling is built for recreational and light-duty commercial boaters who run Hurth transmission systems on small to mid-sized inboards. Weekend fishermen, cruising enthusiasts, and coastal operators rely on flexible couplings to extend drivetrain service life and reduce vibration-related failures. The 13 HP rating covers popular small-block inboard engines and auxiliary powerplants common on center console, cabin cruiser, and sportfishing platforms. R & D Marine's polyurethane design outlasts rubber couplings in UV and salt air exposure while delivering superior vibration isolation compared to rigid steel alternatives—critical factors in extended saltwater operation.