A bobbin coupling is a double flange coupling, which is used to extend the boat propeller shaft. They can also be used for making a double flexible coupling with two R&D type flexible couplings. This can provide excellent noise and vibration control, at a very reasonable price.

The 5" R&D bobbin coupling is machine from steel, and the flange will suit many of the most popular marine gearboxes, including 5" nominal gearbox flanges of PRM, Borgwarner Velvet Drive, ZF, Hurth, Volvo Penta and Technodrive gearboxes.

Bobbin coupling dimensions:

a - Flange outside diameter = 5.00"

b - Hole pitch circle = 4.25"

c - Number of holes = 4

d - Hole size = 0.44"

e - Register diameter = 2.50" male on one flange, female on the other

f - Bobbin coupling length = 4.90"

g - Bobbin neck diameter = 3.38"

R & D Marine Bobbin shaft coupling spacer number 202-251