Shaft Zinc of R-29?

[Emerson]

Our regular diver in our old marina insisted that our 2022 R-29 would benefit from a shaft zinc (X-7 thin). Our highly recommended diver in our new marina stated that a shaft zinc cannot be fitted on the R-29 as there is not enough space for one. I am NOT referring to the prop zinc ....technically at the very end of the shaft.

We are keeping our boat in the water so until we haul out, ...I can't tell myself. I do have a camera on a stick that I may stick into the water. Until I do, any thoughts? Did diver A know something diver B does not?

 

[Maggie Anne]

I don't know the answer to this but if the prop and the shaft are connected so that there is an electric circuit with the prop, the shaft, and the seawater then wouldn't adding a zinc anywhere along that circuit should be sufficient to protect all the metals in that circuit?

 

[wa7pug]

I don't have a shaft zinc but do have the prop zinc and zincs on trim tabs.
You can get into a while monologue about zincs and the galvanic system, but one thing I found out during my survey (and I was a Navy electrician so it rang home): the grounding system runs to the gearbox, and gearboxes have oil ... oil is a dielectric. So as the gearbox runs, you are getting a square wave DC on/off/on/off thing going there. I mounted a 3x6" zinc on the transom and ran a ground wire from the existing system to that, and it makes one heck of a difference.
Also my exhaust port metal chrome fitting holding the flap was rusting - there was no wire inside running from ground to the bolt(s) holding the flap fitting. You need to look at yours and see if you have same condition.

You can also buy a cheap ROV - or hire someone (although by the time you can hire someone, you could own a ROV) to do hull inspection stuff. I have one and later this spring I could come over if you need (I am in Grays Harbor so it is a hike), but you might want to just give your existing system a sharp eye and see if you can improve it.

 

[wa7pug]

that was supposed to be "whole monologue"; not 'while monologue' .... sorry

 

[Emerson]

Thanks. I am goign to stick my camera down there to have a look. One diver claiming that there is space for an additional zinc on the shaft, the other claiming there is not. I am guessing that there is a possibility to place a rather thin/slim zinc and it is so rare that my current diver has not heard of it.

In total our boat has six zincs that seem to be doing a fine job as long as we change them frequently enough. I was just curious if there is indeed a spot for another to marginally improve the protection.

 

[Mike and Sarah]

On our R31 there is enough room to fit a LC-7 micro thin collar zinc. It is 11/16 inch wide. We have one on and replace it every time the prop zinc is replaced. About 6 months.