R & D Flexible Shaft Coupling f/5" Yanmar - 10HP/100RPM Capacity

The R & D Flexible Shaft Coupling for 5" Yanmar with 10HP/100RPM capacity is a precision marine coupling engineered to absorb misalignment and vibration in small-displacement inboard propulsion systems. Built by R & D Marine, a recognized manufacturer of flexible couplings for recreational and commercial fishing vessels, this coupling bridges the engine output shaft to the marine drive shaft while accommodating the dynamic movement inherent in boat structures.

The coupling features a contoured polyurethane flexible disc designed to manage temporary misalignment caused by engine deflection on vibration-isolation mounts or structural flexing during operation. The disc geometry provides clearance for fastener heads while distributing forward thrust in compression across the coupling body. This design minimizes shock load transmission to both engine and shaft seals—critical for protecting expensive transmission and outdrive components. At 10 horsepower and 100 RPM nominal capacity, the coupling is sized for Yanmar 5-inch applications typical of mid-range fishing boats and small commercial vessels where reliability directly impacts uptime and safety.

This coupling is the correct replacement for Yanmar inboards experiencing coupling wear, corrosion, or vibration issues. Weekend fishermen maintaining older 25–35-foot boats and offshore captains running consistent duty cycles both depend on flexible couplings to extend drivetrain service life. Proper coupling condition directly affects fuel efficiency, noise levels, and the longevity of cutless bearings and shaft seals—maintenance considerations that separate experienced boat operators from casual users. At 3.6 lbs and compact 8 x 4 x 8-inch dimensions, installation fits standard engine compartment layouts without structural modification.