Reply
 
Thread Tools Search this Thread Display Modes
 
Old 02-15-2019, 03:43 PM   #1
Senior Member
 
Knot Salted's Avatar
 
City: Muskegon, MI
Country: USA
Vessel Name: Knot Salted
Vessel Model: 1981 Californian 34 LRC
Join Date: Mar 2015
Posts: 174
'Zinc' Analysis II

Greetings.

I am diverging too far from the original questions here, so starting a new (old subject I am sure..) page.

When we bought her, Knot Salted had only one large zinc plate anode on the transom to which all water contacting metal on the boat including seacocks, through hulls, Struts, rudders, engines and trannys were bonded. Not much erosion of the plate over 6 or more seasons including some with the PO, and no obvious erosion of any components visible. She has always been in fresh water.

We have had a few new neighbors at the dock, but no changes over the last two seasons. Last year I went to magnesium anodes, replacing the transom zinc, and adding mags to trim tabs and prop shafts. Rudders are bonded to the transom anode, and no mags were added to them directly.

My reasoning for the swap and additions was reading about zinc being of little real protection in fresh water, magnesium being a better choice, and wanting more coverage - just in-case of a change at the marina.

After one season, all the mag anodes are really chewed up. -I mean they will bite you if you grab them. The bulk of each of them is still present. At the end of this season, I will need to replace all for sure. Of course Mag is much more reactive, but it is still very surprising.

Have I created electrolysis? All mag anodes are mounted on directly bonded parts, except for the new prop shafts mags.

All anodes are Magnesium. No Zinc. Maybe this is my new normal?
__________________
Advertisement

Knot Salted is offline   Reply With Quote
Old 02-15-2019, 04:05 PM   #2
Guru
 
Comodave's Avatar
 
City: Au Gres, MI
Country: US
Vessel Name: Never Say Never
Vessel Model: President 41 DC
Join Date: Jul 2015
Posts: 3,242
Yes, you are now actually protecting your underwater metal. Zinc tends to get a coating in fresh water that will stop it from eroding. That is probably what you were seeing with no wastage of the zinc anode. Now with magnesium you are seeing normal erosion of the anode. We are in fresh water also and use aluminum anodes since I cannot get my hull anodes in magnesium. We see about 40 to 50% wastage in a season here. My boat is docked behind our house with no other boats within 200í. So we donít have other boats causing our anode erosion.
__________________

Comodave is offline   Reply With Quote
Old 02-15-2019, 04:13 PM   #3
Senior Member
 
Knot Salted's Avatar
 
City: Muskegon, MI
Country: USA
Vessel Name: Knot Salted
Vessel Model: 1981 Californian 34 LRC
Join Date: Mar 2015
Posts: 174
Good to know. I am glad we do not seem to have damage for such long exposure...

I was wondering about going to aluminum. Still protective in a hostile environment, but not going for nothing like these mags seem to be doing.

Thoughts?

...and I do want to get over there to see that President!
Knot Salted is offline   Reply With Quote
Old 02-15-2019, 04:43 PM   #4
Guru
 
Comodave's Avatar
 
City: Au Gres, MI
Country: US
Vessel Name: Never Say Never
Vessel Model: President 41 DC
Join Date: Jul 2015
Posts: 3,242
I would have gone with magnesium if there was one that would fit on my hull mounts. I didnít want to drill new holes to fit what was available in magnesium. I do use magnesium in my heat exchangers since I could not find aluminum anodes in that size. It is ok to use different type of anodes in the heat exchangers and on the hull since they are considered different bodies of water. Aluminum anodes can also be used in salt water but not magnesium.

Anytime you are this way you are more than welcome to stop and see my baby. I am always ready to talk boats. While we donít get over to the sunset side often, I would also like to see your baby if we do get over there.
Comodave is offline   Reply With Quote
Old 02-16-2019, 08:35 AM   #5
Senior Member
 
Knot Salted's Avatar
 
City: Muskegon, MI
Country: USA
Vessel Name: Knot Salted
Vessel Model: 1981 Californian 34 LRC
Join Date: Mar 2015
Posts: 174
Sounds good Dave,

I did recall reading on the zinc for salt, and Al and Mg for fresh, but had forgotten that zinc becomes somewhat sealed in fresh water if not in an 'electrically' active environment.

Thanks for that!
Knot Salted is offline   Reply With Quote
Old 02-16-2019, 08:51 AM   #6
Veteran Member
 
Flybull's Avatar
 
City: USA
Country: United States
Join Date: Dec 2018
Posts: 74
Have there been any changes at all made to the electrical/electronics in the boat coincidental of the new anodes...?
Flybull is online now   Reply With Quote
Old 02-16-2019, 09:42 AM   #7
Senior Member
 
Knot Salted's Avatar
 
City: Muskegon, MI
Country: USA
Vessel Name: Knot Salted
Vessel Model: 1981 Californian 34 LRC
Join Date: Mar 2015
Posts: 174
No, nothing new.
Good question though.
__________________

Knot Salted is offline   Reply With Quote
Reply

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off





All times are GMT -5. The time now is 08:34 AM.


Powered by vBulletin® Version 3.8.8 Beta 4
Copyright ©2000 - 2019, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2006 - 2012