4.75 pcd

Coupling:            6.38 diameter

                                        1.88 length

                                        20hp per 100rpm

The R&D Flexible Couplings are fabricated from a contoured flexible disc molded in tough yet resilient new type polyurethane. The contoured disc gives clearance for the bolt heads, and is able to flex freely to take up any temporary misalignment of the engine and shaft, due to flexing of the boat structure or the engine moving on its rubber vibration isolation mountings. Forward thrust is taken in compression on the disc between the two half couplings and reverse thrust is taken again in compression on the disc between the two fail straps. In the unlikely event of a disc failure the steel straps make the coupling fail safe and ensure drive is maintained in both forward and reverse.

To calculate power of coupling required:
Horse Power of Engine _{x Reduction Ratio x 100 = HP/100RPM}
      Engine Speed