Flexible Coupling & grounding - SailNet Community

   Search Sailnet:

 forums  store  


Quick Menu
Forums           
Articles          
Galleries        
Boat Reviews  
Classifieds     
Search SailNet 
Boat Search (new)

Shop the
SailNet Store
Anchor Locker
Boatbuilding & Repair
Charts
Clothing
Electrical
Electronics
Engine
Hatches and Portlights
Interior And Galley
Maintenance
Marine Electronics
Navigation
Other Items
Plumbing and Pumps
Rigging
Safety
Sailing Hardware
Trailer & Watersports
Clearance Items

Advertise Here






Go Back   SailNet Community > On Board > Gear & Maintenance
 Not a Member? 
  #1  
Old 06-08-2009
trantor12020's Avatar
Senior Member
 
Join Date: Mar 2006
Location: Singapore
Posts: 668
Thanks: 1
Thanked 10 Times in 10 Posts
Rep Power: 9
trantor12020 is on a distinguished road
Flexible Coupling & grounding

I've helped a friend install a flexible coupling to his prop shaft. According to the instruction a ground wire should be connected across the flanges if grounding is required. Question is, if the shaft and prop are not ground and is insulated from the rest of boat system then there shouldn't be any cathodic action to eat away the prop ...right ?
__________________
Ken
2002 Hunter 326, SV Millennium 2
1999 Macgregor 26X, SV Millennium
Reply With Quote Share with Facebook
  #2  
Old 06-08-2009
Senior Member
 
Join Date: Aug 2006
Location: Arlington, VA
Posts: 1,807
Thanks: 0
Thanked 4 Times in 4 Posts
Rep Power: 9
btrayfors will become famous soon enough btrayfors will become famous soon enough
It depends...on how the rest of the grounding system is set up, on nearby boats in marinas, stray currents, etc.

However, the more important question has to do with a proper ground for the boat's AC and DC systems. There should be ONE grounding point for AC and DC systems, and it needs to be in contact with the water. Normally, this is the engine.

However, if you install a flexible coupling it's a very good idea (imperative) to make sure the shaft and prop are grounded to the engine.

You protect the prop and other underwater metals with sacrificial zincs.

Bill
Reply With Quote Share with Facebook
  #3  
Old 06-08-2009
Maine Sail's Avatar
Senior Member
 
Join Date: Jan 2003
Location: Maine Coast
Posts: 5,273
Thanks: 9
Thanked 113 Times in 83 Posts
Rep Power: 15
Maine Sail is just really nice Maine Sail is just really nice Maine Sail is just really nice Maine Sail is just really nice
This is what

This is what the ABYC has to say. ABYC is NOT mandatory but a suggested good standard based on years of combined experience by its many voting members.

From ABYC P-06 standard:

6.5.5.2 If a non-conductive flexible coupling is used, an alternative means of grounding the shaft must be provided.

If the engine is acting as the ground point, which it is on most boats being built, then you'll either need to jump over the coupling with a wire or find an alternative means of grounding the shaft. They are fairly clear that the shaft should be grounded, they actually used the words "must be grounded".....
__________________
______
-Maine Sail / CS-36T


To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.




© Images In Posts Property of Compass Marine Inc.


Reply With Quote Share with Facebook
  #4  
Old 06-08-2009
trantor12020's Avatar
Senior Member
 
Join Date: Mar 2006
Location: Singapore
Posts: 668
Thanks: 1
Thanked 10 Times in 10 Posts
Rep Power: 9
trantor12020 is on a distinguished road
So even if I leave the shaft and prop "floated" (not ground) it has detrimental effect ? Where would the leakage current flow to and from ?
__________________
Ken
2002 Hunter 326, SV Millennium 2
1999 Macgregor 26X, SV Millennium
Reply With Quote Share with Facebook
  #5  
Old 06-08-2009
Maine Sail's Avatar
Senior Member
 
Join Date: Jan 2003
Location: Maine Coast
Posts: 5,273
Thanks: 9
Thanked 113 Times in 83 Posts
Rep Power: 15
Maine Sail is just really nice Maine Sail is just really nice Maine Sail is just really nice Maine Sail is just really nice
Dissimilar

Dissimilar metals submerged in electrolyte/salt water will create galvanic issues on their own. Stainless shaft/bronze prop/electrolyte..
__________________
______
-Maine Sail / CS-36T


To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.




© Images In Posts Property of Compass Marine Inc.


Reply With Quote Share with Facebook
  #6  
Old 06-08-2009
trantor12020's Avatar
Senior Member
 
Join Date: Mar 2006
Location: Singapore
Posts: 668
Thanks: 1
Thanked 10 Times in 10 Posts
Rep Power: 9
trantor12020 is on a distinguished road
Ok, just to be on safe side, I'll get my friend to loop a small wire across the flanges. Thanks for the heads up.
__________________
Ken
2002 Hunter 326, SV Millennium 2
1999 Macgregor 26X, SV Millennium
Reply With Quote Share with Facebook
Reply


Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools

 
Posting Rules
You may post new threads
You may post replies
You may post attachments
You may edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On


Similar Threads
Thread Thread Starter Forum Replies Last Post
Flexible bellows exhaust connection FishSticks Gear & Maintenance 7 11-17-2007 09:42 AM
flexible fuel tanks ladydiane Gear & Maintenance 4 02-23-2007 11:52 PM
Flexible shaft coupling zerubb Gear & Maintenance 1 08-18-2006 11:13 PM
Understanding Grounding and Bonding Kevin Hughes Gear and Maintenance Articles 0 02-09-2004 07:00 PM
Flexible water tanks VinceJones Gear & Maintenance 1 11-11-2001 04:18 AM


All times are GMT -4. The time now is 03:39 AM.

Add to My Yahoo!         
Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2014, vBulletin Solutions, Inc.
SEO by vBSEO 3.6.1
(c) Marine.com LLC 2000-2012

The SailNet.com store is owned and operated by a company independent of the SailNet.com forum. You are now leaving the SailNet forum. Click OK to continue or Cancel to return to the SailNet forum.