My diver notified me that its time for bottom paint and that there is noticable corrosion on the strut. He suggested that a hole be drilled in the strut and a zinc added there. is thois recommended? I have never seen any discussion on the board of anyone doing this. I plan to haul the boat next week for paint, so this would be a good time to add this. Thanks in advance.
There is a zinc on the the strut on Unzipped. I did not put it on - I have changed it. It was put on by my dealer during commisioning. A hole was drilled thru the strut and a 3" diameter clamshell zinc intatlled.
JACK....... I hope you don't have too much damage. I assumed most boats had strut zincs. When you install your new zinc be sure to sand down to bare metal on the strut so you have good metal to metal contact. Also when applying the zinc, screw it on and then tap it firmly with a hammer to seat it, then tighten it again. Treat your propshaft zinc the same way........PAUL
Jack
Aquavite has a strut zinc in addition to the shaft zinc. Always had both.
Stu
Mariposa has a 3 inch zinc I installed 3 yrs ago. I'm due for a haulout this year. I did all of the above suggestions submitted by everyone else. :D
My '97 did not have a strut zinc when I purchased it in 2002. Slight current damage was noted by the surveyor at that time. A strut zinc was recommened by the surveyor which I installed.
Jack : I've never had erosion in the past 17 seasons with only a shaft zinc. However, my shaft is isolated from the engine. Interesting!
APACHE #788 :wink:
Hmmm... just saw one on BlackDragon's survey video for the first time. I'll be adding one!
Jack
A strut should have an anode if it isn't electrically bonded to something else that has an anode.
But it needs to be completely electrically connected to the strut (not "just" drill a hole.)
Are you on shore power or on a ball?
Some musings on anodes:
https://marinehowto.com/anode-installation-best-practices/
bookmark these
https://marinehowto.com
http://www.pbase.com/mainecruising/boat_projects
ken
I can't speak or Jack, but his post was 14 years ago. :)
My boat is in a slip on shore power.
Mike
MIKE
OMG that's funny. It was a long hard day yesterday.
k
Yep, installed a zinc on the strut 14 years ago and have never had a problem, even with shore power on my dock.
Jack
I have a 4 zincs on my boat.
1. Prop Shaft
2. Strut
3. Flexofold prop cone nut
4. Heat exchanger
Make sure on the strut to remove any bottom
Paint/primer on the strut so that zinc makes full contact with strut.
I've never had an anode on the strut and have not noticed any galvanic corrosion. I thought the cutless bearing isolated it from the shaft. Also, the shaft is isolated from the engine and the Flex o Fold prop has an anode, as does the shaft. Has anyone previously without an anode on the strut had a corrosion issue that was subsequently resolved by adding an anode to it?
Regards,
Ed
Yup, I have. When I bought my 1999 boat in 2003 there was mild "pinking" of the strut as a result of electrolysis. I put on a 3" clam zinc and no deterioration from that point.
A couple points here for the sake of accuracy
First the attack on the bronze could certainly be due to galvanic corrosion ( if there was electrical conductivity) but "pinking" is more often associated with dezincification (chemical change,) which is a different animal and has no direct relationship to stray current.
Applying a less noble metal to the strut can prevent this.
Electrolysis is separating water into oxygen and hydrogen by passing a current through it (like what happens when charging a wet cell battery.). Or is depilitating (killing hair roots) using a "zap".
What happens to metals on vessels is "galvanic corrosion", not "electrolysis."
K