Cruisers Forum
 


Join CruisersForum Today

Reply
 
Thread Tools Rate Thread Display Modes
Old 15-02-2015, 11:11   #1
Registered User
 
Suijin's Avatar

Join Date: Feb 2013
Location: Annapolis MD; currently in Oriental NC
Boat: Valiant 40
Posts: 3,309
The extreme end of electrolysis

I was recently shown this sail drive by a mechanic. It and it's mate were installed brand new on a catamaran. Three weeks later, after sitting at a mooring with a stray wire on the ground strip, this is what they looked like. Rather remarkable what can happen in three weeks. Don't underestimate the power of electricity to ruin your day.

__________________

Suijin is online now   Reply With Quote
Old 15-02-2015, 11:21   #2
Registered User

Join Date: Oct 2011
Location: Wherever the wind takes me
Boat: Bristol 41.1
Posts: 843
Re: The extreme end of electrolysis

Holy crap!

That's the aluminum portion that dissolved, I assume!?
__________________

redsky49 is offline   Reply With Quote
Old 15-02-2015, 11:24   #3
Registered User
 
Suijin's Avatar

Join Date: Feb 2013
Location: Annapolis MD; currently in Oriental NC
Boat: Valiant 40
Posts: 3,309
Re: The extreme end of electrolysis

I didn't take a close look at it, just snapped the pic. Evidently the owner was a DIY electrician.
Suijin is online now   Reply With Quote
Old 15-02-2015, 12:28   #4
Moderator
 
JPA Cate's Avatar

Join Date: Nov 2011
Location: aboard, cruising in Australia
Boat: Sayer 46' Solent rig sloop
Posts: 12,240
Re: The extreme end of electrolysis

Thus can saildrives ruin your day. Friends had one eaten by one day in a marina with a faulty ground.

Ann
__________________
Who scorns the calm has forgotten the storm.
JPA Cate is offline   Reply With Quote
Old 15-02-2015, 12:42   #5
Registered User
 
Dave852's Avatar

Join Date: Mar 2007
Location: Tavernier, Fl
Boat: Outremer 50
Posts: 664
Send a message via Skype™ to Dave852
Re: The extreme end of electrolysis

The aluminum went first because it was the less noble metal. But if you wired the boat that wrong you would be replacing the shaft and prop on a shaft drive boat. I've seen it happen.


Sent from my iPhone using Cruisers Sailing Forum
Dave852 is offline   Reply With Quote
Old 15-02-2015, 12:47   #6
Senior Cruiser
 
Steadman Uhlich's Avatar

Cruisers Forum Supporter

Join Date: Jul 2014
Location: Crewing All of 2018 Available Globally
Boat: OPB = Available as Crew in 2018
Posts: 5,528
Re: The extreme end of electrolysis

Wow!

Thanks for posting this photo showing the fast damage. Amazing! Scary!
__________________
Ahoy All Sailors! Need experienced crew for a passage or delivery in Atlantic, Pacific, Caribbean, Med, PNW, ICW, coastal or across an ocean anytime in 2018? I am available on 24hr notice. See my CF Profile "About Me" page for details. Happy to lend a hand!
Steadman Uhlich is offline   Reply With Quote
Old 15-02-2015, 14:04   #7
Registered User
 
CS Cruiser's Avatar

Join Date: Mar 2013
Location: PCYC Toronto
Boat: CS36T
Posts: 311
Images: 10
Re: The extreme end of electrolysis

Nasty!
__________________
Paul
s/v TENACITY - CS36T
CS Cruiser is online now   Reply With Quote
Old 15-02-2015, 14:58   #8
Moderator
 
Dockhead's Avatar

Cruisers Forum Supporter

Join Date: Mar 2009
Location: The boat: Cowes (Winter), Above 60N (Summer); me: somewhere in the air!
Boat: Cutter-Rigged Moody 54
Posts: 21,276
Re: The extreme end of electrolysis

By "sitting at a mooring" did you mean in the absence of shore power? Or was it in a marina?
Dockhead is online now   Reply With Quote
Old 15-02-2015, 15:08   #9
Registered User
 
LeaseOnLife's Avatar

Join Date: Apr 2008
Location: out cruising again
Boat: Sailboat
Posts: 1,085
Re: The extreme end of electrolysis

Quote:
Originally Posted by Dockhead View Post
By "sitting at a mooring" did you mean in the absence of shore power? Or was it in a marina?
I too would like a better description of the failure mode!

Dirk
LeaseOnLife is offline   Reply With Quote
Old 15-02-2015, 16:47   #10
Registered User

Join Date: Nov 2014
Posts: 694
Re: The extreme end of electrolysis

This wasnt electrolysis. Electrolysis is a slow erosion of metal as a result of differences in galvanic potential, and is normally protected against with sacrificial anodes. This photo depicts stray current corrosion, where DC current either from within or from outside the vessel flows through the component.

Obviously fatal to aluminum saildrives, but can also turn bronze props into swiss cheese.

DougR
DougR is offline   Reply With Quote
Old 15-02-2015, 18:27   #11
Marine Service Provider
 
Maine Sail's Avatar

Join Date: Jan 2007
Location: Maine
Boat: CS-36T - Cupecoy
Posts: 3,105
Re: The extreme end of electrolysis

DC corrosion can happen very quickly with a bad leak....
__________________
Marine How To Articles
Maine Sail is offline   Reply With Quote
Old 16-02-2015, 10:30   #12
Registered User
 
Suijin's Avatar

Join Date: Feb 2013
Location: Annapolis MD; currently in Oriental NC
Boat: Valiant 40
Posts: 3,309
Re: The extreme end of electrolysis

Quote:
Originally Posted by DougR View Post
This wasnt electrolysis. Electrolysis is a slow erosion of metal as a result of differences in galvanic potential, and is normally protected against with sacrificial anodes. This photo depicts stray current corrosion, where DC current either from within or from outside the vessel flows through the component.

Obviously fatal to aluminum saildrives, but can also turn bronze props into swiss cheese.

DougR
Indeed, I misspoke.

As for clarification regarding the location of the boat, all I know it was "away from the dock, at a mooring" and that the culprit was the boat's own electrical, but I couldn't tell you more than that.
Suijin is online now   Reply With Quote
Old 16-02-2015, 11:00   #13
Registered User

Join Date: Sep 2014
Posts: 408
Re: The extreme end of electrolysis

coomon problem with sail drives and IO's needs a galvanic isolator
bsurvey is offline   Reply With Quote
Old 16-02-2015, 11:09   #14
Registered User

Join Date: May 2006
Location: Cruising the east coast.
Boat: 1994 Fountaine Pajot Tobago-35 "Lauren Marie"
Posts: 63
Re: The extreme end of electrolysis

Same thing happened to my sail drives in 2007. Turned out that the shore-power battery charger had gone bad. That's scary unto itself as there were no signs other than the "missing" saildrives.

I installed a galvanic isolator and have had no electrolosis/galvanic issues since..

One of mine is hanging on the wall in Bay Shore Marine at Burt Jabins.
mfeene01 is offline   Reply With Quote
Old 16-02-2015, 11:13   #15
Moderator
 
a64pilot's Avatar

Cruisers Forum Supporter

Join Date: Oct 2013
Location: Albany Ga.
Boat: Island Packet 38
Posts: 18,410
Re: The extreme end of electrolysis

Quote:
Originally Posted by Maine Sail View Post
DC corrosion can happen very quickly with a bad leak....
But it has to be DC, right? Can't be AC?
So why do I hear all the horror stories about bad shorepower pedestals in Marina's etc.?
Is that a bunch of nonsense?
How can a neighbors boat be the problem, I've heard that for years, is it true?

On edit, if it can't be AC, then why do I have an isolation transformer isolating my boats ground on the AC side from shorepower?

I'm not doubting, but I am confused.
__________________

a64pilot is offline   Reply With Quote
Reply

Tags
electrolysis

Thread Tools
Display Modes Rate This Thread
Rate This Thread:

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


Similar Threads
Thread Thread Starter Forum Replies Last Post
End to End Splicing Sta-Set of Different Diameters chris95040 Deck hardware: Rigging, Sails & Hoisting 3 21-07-2014 14:26
Chain End to End or Not Sandiiyam48t Anchoring & Mooring 9 22-12-2013 11:45
Great Lakes End to End HoppySailor General Sailing Forum 21 16-11-2013 10:39
High-end vs. low-end line? FlyMeAway Deck hardware: Rigging, Sails & Hoisting 20 10-05-2013 04:58
End-to-end splicing braided line Time Traveler Deck hardware: Rigging, Sails & Hoisting 4 25-04-2013 20:02



Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -7. The time now is 05:13.


Google+
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2018, vBulletin Solutions, Inc.
Social Knowledge Networks
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2018, vBulletin Solutions, Inc.

ShowCase vBulletin Plugins by Drive Thru Online, Inc.