zinc for prop shaft

[LISal]

I recently changed my cutlass bearing. When doing so the mechanic noted that the zinc on the shaft was impeding the water flow to the cutlass bearing. I could see that it is a very short distance between the bearing and prop. We decided to run some cable and relocated zincs on the rudder bar to bond the entire area. I think it came out nice and will share some pics this winter. Has anyone else found this to be an issue? I knew the bearing was on its way out when i bought the boat last year. Really didn't want to have to change it again, sooner than i had to because of lack of water to the area. Any insight is always appreciated. I also installed a large puck zinc on the rudder instead of the smaller one previously installed. We do a lot of hours and a 20 dollar zinc can save me a huge expense I understand. I was surprised to see how much they get eaten up in a couple hundred hours.

[PeterYOW]

LIS. I may be wrong but I think you have to have direct bonding of your prop shaft for anodic protection. Bonding the "area" by means of your rudder won't work. Did you consider bonding the prop shaft inside the boat with a contact on the rotating shaft and electrically bonding THAT contact to a zinc?

[LISal]

yes we ran stainless inside and out to complete the circuit if that's the correct word. we have bonded the shaft hence the custom work. We had to replace the zinc and just located it on the rudder bar but its bonded to the shaft. I will take some pics. Has anyone else had issues with the cutlass bearing? Or do you believe the design is fine as is?

[jleonard]

There is a "prop nut" zinc that attaches to the end of the prop shaft. Available at boatzincs.com
I have also cut donut zincs to fit in narrow space between prop and cutlass.
both protect the shaft.

[LISal]

The prop nut zinc sounds like a good addition and will be added when i pull her. Just hoping to get a couple more fishing trips in. I am on my way to the boat now to grab the tuna gear that window looks like its closed for me. I will do some blackfishing and then wrap her up. Thank you for the knowledge of the prop nut zinc.

[Tree]

For what it’s worth I bond my shaft through the gear box. I’ve scraped away a small amount of paint on the bell housing and ran an earthing strap direct back to the boats bonding circuit. This allows me to not only check for continuity when the boat is out of the water but also while the boat is in the water should there be any beak down on the circuit. If you have a flexible coupling, just run a cable from one side to the other.

[MerryKate]

LISal - i always thought about this when changing zincs but never had a problem with my cutlass bearing, which is still solid over 23 years and about 1800 hrs.

Not much room for the doughnut zinc but I try to leave it closer to the prop keyway to let as much water through the bearing passage as possible. (I always make sure the water passages are clear after bottom painting.). Not sure if this photo will replicate from a very old
post here:

http://i172.photobucket.com/albums/w35/ ... 140389.jpg

Albin seemed to do a reasonably good job in electrical bonding on my 1997 28TE but I have always been moored in fresh water. Only have to change zincs about every 2 years.