use of a collar shaft zinc instead of a prop zinc?

[Mikep]

My 31S with the D4 300 will many times throw off the prop zinc well before it needs replacement. I have a professional service clean my boat and replace the zincs so I assume they know how to install properly. With previous boats I had zinc collars on my shaft instead of prop zincs. Has anyone gone this route over the prop zincs with success?

 

[Mike and Sarah]

We added a LC-7 micro thin collar. 1.5 inch shaft along with the prop nut. It did extend the prop zinc. The lc7 is the only one that will fit the narrow clearance.

 

[lproulx]

We added a LC-7 micro thin collar. 1.5 inch shaft along with the prop nut. It did extend the prop zinc. The lc7 is the only one that will fit the narrow clearance.

At other end of Ranger size spectrum, had same problem with my 21ec. Collar works great. Would have been nice if they made the prop shaft about an inch longer so a more commonly available oval zinc would fit. Only reservation was whether zinc would interrupt water flow around prop, but max speed and wot rpm same same as before. Blades near hub don't do much.

Larry

 

[Rode Trip]

At other end of Ranger size spectrum, had same problem with my 21ec. Collar works great. Would have been nice if they made the prop shaft about an inch longer so a more commonly available oval zinc would fit. Only reservation was whether zinc would interrupt water flow around prop, but max speed and wot rpm same same as before. Blades near hub don't do much.

Larry

The standard is that you don't want more than one shaft diameter of shaft length between the strut or cutless bearing and the prop. This is to reduce 'shaft whip', or torque from the prop causing excessive stress to the shaft.