Re: [Amel Yacht Owners] Grounding


karkauai
 

Hi Paul.  It's very important that you understand the bonding system.  If not correct, your underwater metals are at risk of galvanic and possibly electrolytic corrosion.

There are five "grounding" systems on your boat.  They are mostly separate from each other.  Three of them use yellow/green wires...very confusing.

1.  The bonding system connects all metals exposed to sea water.  It is ultimately connected to the zincs on the rudder via a large y/g wire from the engine or aft end of the angle iron engine supports.  It runs aft along the port side and ends at the rudder post under the starboard seat in the aft cabin.  It connects to the stainless skeleton of the rudder, and the zincs bolt into that skeleton.  It also connects to the discharge valve and intake through-hull for the aft head, and forward metals exposed to sea water at the A/C pump discharge and (I think) the bow thruster. All metals exposed to sea water should show a solid connection to this system and therefore to the zincs.  Most of the bonding wires from forward of the engine room connect to the copper strap that bolts to the keel in the bilge sump, and a large wire also goes from that strap to the engine or its angle iron bed.
Get a long enough wire to get to all parts of the boat and check the resistance between the rudder post and the zincs.  There should be NO resistance (i.e. a solid connection). Then check for resistance between rudder post and all metals exposed to sea water. Anywhere you find more than minimal resistance, check the connections and repair.  A fault in any raw water pump may make a connection between the DC system and bonding.  This most commonly occurs at the macerator pumps for the heads.

2.& 3.  DC ground, both 24v and 12v systems.  Wires are usually blue, but if work has been done in the US they are probably black.  All negative wires should run from the motor or other appliance directly to the 12 or 24v battery negative...NOT through the engine block as is typical on US manufactured boats.  (The only exception is the start, stop, and glow plug wires from engine and generator.  These are grounded to the engine, but the large wire that connects the engine block to the battery negative (12v system) goes through a solenoid that makes negative connection only when glow, start, or stop is activated.  This is an "isolated ground" system.  It does NOT connect to the bonding system except for the brief time that the engine or generator are being started or stopped.)  If you find a connection between battery negative and the bonding system, something is connected wrong and should be corrected.

4.  220AC ground.  These are y/g wires just like the bonding system.  They should lead from 220 appliances back to the boat's 220 ground, not through the bonding system.  There are a few places where a connection to the bonding system may occur, such as the AC Watermaker pump or Air Conditioner raw water pump, and at the generator (see earlier posts).

5.  Single Sideband Antenna ground.  This is also a g/y wire like the bonding system, marked BLU where it comes into the navigation station.  It should connect the SSB radio to the antenna (and the copper strap in the aft lazarette, and the SSB plates on the rudder), NOT to the bonding system.  In boats that did NOT come from Amel with a SSB radio, this g/y wire marked BLU is connected to the bonding system at a post behind the Nav station.  If your SSB was added later, it may still be connected to the bonding system, and should be disconnected.

I'm pretty sure this is all said correctly, anyone who sees something that's not right, please correct me.  After any corrections are made, I'll post it to the Files section.

Hope this is clear, Paul.  If not I'll try again..

Kent
SM 243
Kristy




On Mar 1, 2016, at 10:31 AM, 'Bill & Judy Rouse' yahoogroups@... [amelyachtowners] <amelyachtowners@...> wrote:

 

Paul,

You said, "The bolts on the rudder holding the zink are not connected electrically with each other."

The bolts on the rudder holding the zincs SHOULD be connected electrically with each other and to the bonding system. You should be able to check continuity between the propeller shaft and the zincs on the rudder. If there is not continuity (electrical connection) between the propeller shaft and the zincs, you probably have a problem with the bonding system not being connected to the motor and C Drive.

Bill
BeBe 387

On Tue, Mar 1, 2016 at 1:54 PM, osterberg.paul.l@... [amelyachtowners] <amelyachtowners@...> wrote:
 

Thank you Vladimir

I have tried your concept with  cleaning and now they conduct and have electric contact with the copper strip in the lazaret. Don't understand what you mean by all grounds connect to the rudder. I have checked and there are no connection with the zink on the rudder I believe, and do not understand how it could be. The bolts on the rudder holding the zink are not connected electrically with each other
Paul on S/Y Kerpa SM#259


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