So in the haulout for it's Survey, POLARIS's (our brand-new 1979 Pearson 365 Ketch) strut was found "of being electrolysis hot, pink in color from possible missing zinc".
Three Questions:
1. What is the strut made from in the first place?
2. Once she arrives in Alaska and I pull her for bottom painting and zinc replacement, what do I need to do about the pink surface corrosion form being "electolysis hot"?
3. Other than the two collar zincs on the propeller shaft, are there any other zincs to protect the strut?
Respectfully,
Dave Allen
Hi Dave,
1. Your strut is made of bronze.
2. You will need a professional to make the decision about how bad the strut is. Hopefully you can find a reputable and experienced boatyard to check it out. If the zinc is badly corroded, the metal has started to break down, and it will be brital. A guy at my marina just sank his boat because a thru-hull got bady corroded and it broke apart. (he never replaced his shaft zincs. A real lesson to all)
3. Most 365's only have two zincs. One on the shaft, and one in the heat exchanger of you engine. The strut should be bonded with a green wire and joined up with your engine block. (as well as ALL other underwater metals) My guess is that your bonding wire has corroded off, or the previous owner did not replace your shaft zinc on a regular basis. If the wire is in bad shape, you need to get that wire replaced. Unfortunately it is located almost under your engine, so it won't be easy. All underwater metals should be protected by your shaft zinc.
You could drill through the strut and add a bolt-on zinc, but it shouldn't need one if your bonding system is working properly.
-Kevin
I WILL be looking into the bonding wire as a possible root cause for the electrolisis. Assuming the strut is still structurally sound, do I just prime and paint?
Yes-
Two part etching primer for underwater metals, then something like interprotect 2000E. After priming your ready for bottom paint. This method will keep the paint from falling off. You can also use this method for your shaft and prop.
Thanks Sir. This will be on my August to-do list!
There's a clamshell zinc on my strut and 2 collars on the shaft.
http://picasaweb.google.com/lh/photo/UV7-4W_JZukJ7uf3AfuubQ?authkey=Gv1sRgCOfdvNLf6qnR6gE&feat=directlink
Marc,
Did you add the clamshell one? Is it simply a matter of drilling a hole and clamping it in place during the haulout?
Dave
Ok Dave....our strut was pink and needed replacing as well. You can still buy a new strut from the orginal mold....the info is this site somewhere....but we were pressed for time and had the boat yard make a new SS one...like $1500 worth of work, where the original bronze one would be cheaper. I'll search the site, because I remember the info being here somewhere!
Rich
Bingo....This thread has some info for you!
http://www.pearson365.com/forum/index.php?topic=127.0
Good luck!