Bonding and Grounding

[dar636]

I'm reworking Bonds and Grounds as I work through bilge areas and have a few inconsistencies... So my question is what has to be bonded? Any metal fitting touching seawater?

My engine seastrainers are isolated from the hull and engines by rubber hoses on each end. No bond straps. Should there be?

My deck fuel fill fittings do have a ground wire running to the bond plane - I assume for spark isolation?

I'm starting with the air conditioning system components after flushing and reclamping everything and just getting going.

 

[racclarkson@gmail.com]

If by chance you have your boats engineering drawings, you’ll find the bonding plan. If not, call Sam’s for a set. My boat had approximately 70 bonding points specd plus a few items added over the years.

 

[rsmith]

If it’s electrically isolated and touching seawater it should be bonded.

 

[racclarkson@gmail.com]

The 70' Hatteras next to me has virtually zero bonding in place. Like Aslan, it's an '83. Unlike Aslan, just about every bonding cable still in place crumbles at the slightest movement, per the new mechanic.

This is a charter boat that has recently had its crew shaken-up for a number of reasons. Subsequently, a disturbing array of very poor maintenance has come to light. The new mechanic states that two of the minor thru hulls were leaking significantly and found to be so thin in places as to be problematic. From talking to their diver, I know the exterior grating on the numerous intakes are largely or completely corroded away. The prior mate was always reporting clogged strainers while I, docked adjacent, had no such issues.

Two years ago, I undertook renewing the bonding on Aslan. With the help of the plans that conveyed with the boat, I found numerous substandard bonds and a few missing altogether. I practically had to dismantle the boat to get to some parts such as struts, but I got them all. Because of the extremely low voltages involved, meters do little other than indicate a severed cable. Peeling back the insulation on the existing wire made it clear that 35+ year old wire won't survive a saltwater environment for even a fraction of that time.

I recently inspected some of my renewed terminal ends looking for a cause of uneven zinc wear. While it's only been two years since renewal, it was good to see the extra time taken to ensure airtight cable terminations is paying off.

Given the state of the other 1983 Hatteras next to me, the bonding system is something that can easily be deemed a deferred maintenance item, but at some peril.

 

[oscarvan]

Question: Does your bonding system have additional anodes, or does it strictly rely on those affixed to the shafts (and possibly rudders) ? Thanks.

 

[racclarkson@gmail.com]

If you’re asking me, no additional anodes. However, I ordered a hanging anode today, so the answer was no before it was a yes.

 

[jrbrein]

As Robert said, having the drawings of the ships bonding plan is a great place to start.

Another tool to have and learn how to use would be a silver chloride reference electrode, Using this with a volt meter, you are measuring the voltage of the corroding zincs which is around - 950 milivolts. When all the bonding points have been successfully connected and they are in contact with an underwater zinc anode, you should be getting the same reading for all of these bonding points. On my boat, there is a copper strap that runs throughout the boat and there were also quite a few corroded wires some just dangling!

I used 6 gauge copper tinned wire, solder less crimp connectors with heat shrink tubing and installed this right on top of the existing bonding wires. I tied the zincs on my rudders into my entire bonding system.

To check my work, I then connect the silver chloride electrode to the negative wire of my voltmeter and hang the electrode over board and then use the positive wire on the voltmeter to check all metals and bonding points for both continuity and to ensure I am measuring the range of zinc actively corroding...not bronze or stainless.

You do not want to commingle your bonding wires with the grounding wires on your AC and DC circuits even if they do have common connections.

Jon

 

[savarese1]

Where did you attach your hanging anode? Thank you

 

[racclarkson@gmail.com]

Plan on clipping onto a bonding strip either in lazarette or ER.

 

[BOATER BOB]

To bond or not to bond two different camps on the subject.
I chose not to bond and run zincs on shafts rudder and struts.
None on thru hulls as good bronze should last on its own.
So far so good for last 6 years.
Bob