Cruisers Forum
 


Join CruisersForum Today

Reply
 
Thread Tools Rate Thread Display Modes
Old 24-10-2015, 08:49   #1
Senior Cruiser

Cruisers Forum Supporter

Join Date: Dec 2012
Location: Englewood, FL
Boat: Gulfstar 50 Ketch
Posts: 78
Electolysis and bonding

Hi All, wanted get some input on bonding and electrolysis. First let me state that I am and electrical engineer and understand the process of electrolysis and the need for bonding.

Bonding is primarily for protection from electrocution if AC power is introduced into the DC circuit (also helps in lightning protection). Bonding’s attribute is to equalize the voltage across all components in touch with water. Very effective, however, in doing so it also creates a path for current flow. Current flow is the means by which electrolysis work. It allows ions from one metal to migrate to another … without a current path, electrolysis will not happen. Think a battery: one with nothing connected (no current flow) and one with both terminals connected (current flow).

So here is my question. Other than local zincs (e.g. prop shaft, iron keels, rudder hinges) and find very few sailboats with the bonding system connected to a zinc. Would appreciate informed opinions as to why and or what others do (if anything). E.g. using a zinc fish when docked at a marina

__________________

__________________
pbbmorton is offline   Reply With Quote
Old 25-10-2015, 18:59   #2
Registered User

Join Date: Jun 2013
Location: canada
Posts: 1,696
Re: Electolysis and bonding

Every bonded boat needs zincs in the system or all the bronze etc will all corrode away naturally. At or away from the dock. You need a permimate one.

Most power boats have a large divers dream bolted to the stern and bonded. Not sure if many Sail boats do this or not. As it's easier with a flat stern
__________________

__________________
smac999 is offline   Reply With Quote
Old 25-10-2015, 20:36   #3
Marine Service Provider
 
fstbttms's Avatar

Cruisers Forum Supporter

Join Date: Oct 2006
Location: Under a boat, in a marina, in the San Francisco Bay
Posts: 3,592
Re: Electolysis and bonding

Quote:
Originally Posted by pbbmorton View Post
I am and electrical engineer and understand the process of electrolysis and the need for bonding.
Then you should know that it's not "electrolysis."
__________________
fstbttms is offline   Reply With Quote
Old 25-10-2015, 21:08   #4
Registered User
 
Stu Jackson's Avatar

Join Date: Jan 2011
Location: Cowichan Bay, BC (Maple Bay Marina)
Posts: 6,385
Re: Electolysis and bonding

Marine Grounding Systems | West Marine
__________________
Stu Jackson
Catalina 34 #224 (1986) C34IA Secretary
Cowichan Bay, BC, (Maple Bay Marina) SR/FK, M25, Rocna 10 (22#) (NZ model)
Stu Jackson is offline   Reply With Quote
Old 26-10-2015, 07:38   #5
Senior Cruiser

Cruisers Forum Supporter

Join Date: Dec 2012
Location: Englewood, FL
Boat: Gulfstar 50 Ketch
Posts: 78
Re: Electolysis and bonding

Quote:
Originally Posted by fstbttms View Post
Then you should know that it's not "electrolysis."
Understood; galvanic corrosion is when two dissimilar metal come in contact. Electrolytic corrosion is created by coming in contact with AC ground from shore or from bad wiring in another boat. Both can cause considerable damage ... it is the electrolytic corrosion I am focused on.
__________________
pbbmorton is offline   Reply With Quote
Old 26-10-2015, 07:39   #6
Senior Cruiser

Cruisers Forum Supporter

Join Date: Dec 2012
Location: Englewood, FL
Boat: Gulfstar 50 Ketch
Posts: 78
Re: Electolysis and bonding

Quote:
Originally Posted by Stu Jackson View Post
Thanks Stu ... great article ... answered my question
__________________
pbbmorton is offline   Reply With Quote
Old 26-10-2015, 08:33   #7
Marine Service Provider
 
fstbttms's Avatar

Cruisers Forum Supporter

Join Date: Oct 2006
Location: Under a boat, in a marina, in the San Francisco Bay
Posts: 3,592
Re: Electolysis and bonding

Quote:
Originally Posted by pbbmorton View Post
Understood; galvanic corrosion is when two dissimilar metal come in contact. Electrolytic corrosion is created by coming in contact with AC ground from shore or from bad wiring in another boat. Both can cause considerable damage ... it is the electrolytic corrosion I am focused on.
No, no... I was only bustin' balls because electrolysis is a term that is constantly and improperly used by boaters. We are taking about electrolytic corrosion, not electrolysis, which is a different process and not one that affects a boat's underwater metal parts.

Just sort of a pet peeve of mine.
__________________
fstbttms is offline   Reply With Quote
Old 26-10-2015, 09:36   #8
Registered User

Join Date: Jan 2008
Location: SF Bay Area (Boat in La Paz)
Boat: Valiant V40
Posts: 432
Re: Electolysis and bonding

I'll offer some anecdotal but real life experience.

We've run our boat for 8 years semi-bonded. That is, we have a galvanic isolator on the AC system and the boat has a hull zinc. Most, but not all thru-hulls are bonded to the hull zinc. The shaft (hence the prop) Is not bonded (shaft brush failed long ago), but there are of course zincs on both the shaft and prop. When in a marina, I generally hang a grounded (to the bonding system) zinc over the side.

To date, I see NO difference in corrosion between the bonded and unbonded thru-hulls. My prop and shaft are fine, and my zinc generally last several months.

The only time that I have problems have been in marinas and moored to a hot boat. In one instance I noticed that my hanging zinc nearly disappeared in less than a month. Problem went away when I moved slips. Shortly after, I added the galvanic isolator and have had no serious issues, but one other time, when near a suspect boat I did notice some additional loss of my hanging zinc.

Finally, I do make it a practice to disconnect from marina power supply when I do not need the power. I have sufficient solar to provide most of our needs when at a slip.
__________________
jamhass is offline   Reply With Quote
Old 26-10-2015, 09:55   #9
Marine Service Provider
 
boatpoker's Avatar

Join Date: Nov 2008
Location: Toronto, Ontario or Bahamas
Boat: Benford 38 Fantail Cruiser
Posts: 2,593
Re: Electolysis and bonding

No qualified marine electrician uses the tern "electrolysis" as that is what happens to the electrolyte not the metals involved.
We should be talking about "galvanic" or "stray current" corrosion.
Bonding is another word often misused as people don't understand the references. Bonding against galvanic corrosion and bonding as a safety path are two different things i.e. two different bonds.

I once surveyed the sailboat of the electrical engineer who did the systems on "Maltese Falcon" .... I declared his electrical sytem a hazard. My slip neighbour just retired as President of IEEE and he readily admits to knowing nothing about electricity on boats although he does know what electrolysis is .

ABYC Certified Corrosion Analyst.
__________________
That hysterical laughter you hear as you sail a way in your "new" boat ..... is the seller.
boatpoker is offline   Reply With Quote
Old 26-10-2015, 12:39   #10
Senior Cruiser

Cruisers Forum Supporter

Join Date: Dec 2012
Location: Englewood, FL
Boat: Gulfstar 50 Ketch
Posts: 78
Re: Electolysis and bonding

Thanks all, and boatpoker you are right sometimes we trip all over our EE! I know enough to ask.
__________________

__________________
pbbmorton is offline   Reply With Quote
Reply

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
Zincs and Bonding Flying Knight Construction, Maintenance & Refit 5 24-05-2014 22:44
Correct grounding and bonding bazzer Electrical: Batteries, Generators & Solar 43 13-03-2013 14:10
Bonding Starboard Sunspot Baby Construction, Maintenance & Refit 12 19-04-2009 04:41
grounding/bonding points rleslie The Library 0 02-12-2005 07:18
Seminar - Grounding vs Bonding GordMay The Library 3 23-07-2005 14:11



Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -7. The time now is 19:17.


Google+
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
Social Knowledge Networks
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.

ShowCase vBulletin Plugins by Drive Thru Online, Inc.