New boat purchase, anode/corrosion questions

[putz]

I know there are other threads on this subject but i'm new here and wasn't sure if I should post new or add on to the other posts

I'm in the process of purchasing my first Marinette, a 1990 32' Sedan and was looking for some advise. First concern is that from what I've read mixing anodes is a no-no. the boat has the normal aluminum strips on the keel, rudder, and trim tabs. But it also has some rather large round anodes on the rudders and the trim tabs that I believe are zinc(they say CAMP R3 on them). It will be, and has been in fresh water on the St. Croix and upper Mississippi around Minnesota and Wisconsin. The aluminum anodes are pretty well spent and the zinc ones appear to be barely used. Problem is that the previous owner has passed and I don't know how long either have been on the boat. I know the aluminum ones need replacing, my question is whether or not to remove the zinc ones or not?? second thing I've noticed is the stbd. prop strut is quite corroded, I have located a replacement but my concern is why it's doing this so I can prevent it in the future. My plan is to completely redo the bottom at the end of the season with the Trilux 33. I would do it now but it officially is not mine until the water trial and from that point I would need to pay to have it hauled out and put back in on top of the bottom job. Any advise on the corrosion or anodes would be appreciated.

[Fastjeff]

Though one is supposed to stick with the mag-al anodes, I too have used the ordinary Al anodes on the steel rudders and on the shafts. (For that matter, that's all one can buy for shafts.)

The MAIN thing here for you to be concerned with is what CAPAC reading the boat is getting NOW. If the owner doesn't know what means, or if the reading is low (under 5 or 6) I would be concerned.

The strut (hard to see) it's pretty stout, so unless it's badly corroded it might be okay. The one on my old boat was a bit ragged looking, but it held up fine for over a decade.

Jeff

[putz]

Thanks for the reply, as I stated, the previous owner is deceased so unfortunately I can't ask him any questions. His widow has stated that everything is working (when pulled anyway) so as soon as we do the water trial I will check the CAPAC reading.

Jim

[jralbert]

Zincs that eaten away more than 50 percent should be replaced (*). The ones I see in the photo that are not worn can be taken off and sanded to expose fresh surface, then put back.
(*- I was cheap so I used to take two half worn zincs, sand them and put them together to act as one zinc. I don't know whether to recommend it so I am just telling you what I did. Had no galvanic corrosion issues. Kept an eye on the Capac)

[Maestro]

To prevent corrosion it would also be worthwhile to check to make sure your propeller shafts are isolated from the hull. Look at the coupling where the shaft connects to the transmission. There should be some type of spacer there preventing metal-to-metal contact between the two halves of the coupling. This isolation prevents the aluminum hull from acting as an anode to the cast iron engine.

If there is no isolation device in place, Google "Globe Drivesaver" for a simple fix...although somewhat pricey, it will guarantee isolation and save your transmission if you hit something real hard with your prop.

Most Marinettes have steel rudders. I wanted to isolate the rudder from the hull so I got creative with nylon washers and heat shrink tubing on the various rudder linkages to accomplish this.