I've noticed that the zincs intended for attachment to prop shafts have
a slightly smaller radius of curvature than the stamped size. I wondered
about this and considered the smacking technique to provide greater
surface area.

Usually, high electrical resistance is not a big problem with this type
of zinc. What is more important is that the mechanical "bite" of the
zinc on the shaft remain tight. If the zinc ID is slightly undersize,
the zinc will contact the shaft at four places. For a given torque on
the attaching bolts, there will be much more pressure (psi) with an
undersize zinc than if the zinc ID were exactly the same as the shaft
OD, where the pressure is spread more uniformly around the circumference
of the shaft. Think about serrations on the jaws of a pair of pliers as
an analog. So I wonder which is really better, assuming both provide
satisfactory electrical contact.

Chuck


Jere Lull wrote:
With all zincs, including the MaxProp: Smack them with a hammer for
better contact, then torque down again. Ours all decay from the outside
mostly.