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[Amel Yacht Owners] Bonding
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The engine should be bonded separately from the CDrive. Kent On Sep 22, 2016, at 8:37 AM, sailw32@... [amelyachtowners] <amelyachtowners@...> wrote:
How is the Cdrive & engine protected , if it not connected to the bonding system. With the silver anode the electrician had a reading over 1000 mv at the C-Drive, and at the strap 804. With the battery connection off, everything off it was 804 , with everything on ,still 804 . I suppose the 804 could be explain by poor zinc/bolt contact and the test being conducted in fresh water. If the engine is not grounded / bonded , how is it protected? Thanks , Pat SM 123 |
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Patrick McAneny
Kristy, Why do you think the drive connection has failed , if it shows Like -1000mv , I may have left off the - in my email , is that why? I guess the engine can be bonded to the zincs without being grounded ? I have no prop zinc , and don't understand how the strap and the Cdrive are so different in their reading.
Thanks ,
Pat -----Original Message----- From: Kent Robertson karkauai@... [amelyachtowners] To: amelyachtowners Sent: Thu, Sep 22, 2016 9:13 am Subject: Re: [Amel Yacht Owners] Bonding Hi Pat. It sounds like your drive connection to the bonding system has failed. Do you have a prop zinc? On Kristy the connection to the bonding system is at one of the bolts on the housing at the top of the vertical drive shaft. Around -1000mv hull potential is correct for your boat. Your 804 (I assume really -804mv) reading indicates under protection of the whole system, so I would first check the connections between the strap and the rudder. I hope you'll find something there, as that would be the simplest thing to fix. If they are all OK, you'll need to check connections of the zincs to the rudder. Only way I know to do that is haul the boat out and check continuity from the zinc to the rudder post. I guess you could remove the zincs and wire brush the bolts and bottle brush the bolt holes with a SS or Brass brush if you can find one.
Let us know what you find.
Kent SM243
Kristy
How is the Cdrive & engine protected , if it not connected to the bonding system. With the silver anode the electrician had a reading over 1000 mv at the C-Drive, and at the strap 804. With the battery connection off, everything off it was 804 , with everything on ,still 804 . I suppose the 804 could be explain by poor zinc/bolt contact and the test being conducted in fresh water. If the engine is not grounded / bonded , how is it protected?
Thanks ,
Pat SM 123
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Pat, if the hull potential is different from the drive than from the engine and everything else, it isn't connected well to the rest of the bonding system. Normally you would see a better reading at the engine than at the drive. If you don't have a prop zinc, I can't explain the findings. If you have two problems, a bad connection at the rudder, and a bad connection at the drive, they would read differently. If you have a prop zinc it could be protecting the drive but the rudder zincs not protecting the rest of the boat. Get in the engine room with your multitester and look for resistance between all bonded parts and the strap, including the rudder post. There should be essentially no resistance between all bonded equipment. To check the zinc connection to the rudder, you have to haul the boat out and run a wire from the rudder post to the zincs and check resistance. Does that make sense? If not, please chime in! Kent SM243 Kristy On Sep 22, 2016, at 11:58 AM, Patrick Mcaneny sailw32@... [amelyachtowners] <amelyachtowners@...> wrote:
Kristy, Why do you think the drive connection has failed , if it shows Like -1000mv , I may have left off the - in my email , is that why? I guess the engine can be bonded to the zincs without being grounded ? I have no prop zinc , and don't understand how the strap and the Cdrive are so different in their reading.
Thanks ,
Pat
-----Original Message-----
From: Kent Robertson karkauai@... [amelyachtowners] <amelyachtowners@...> To: amelyachtowners <amelyachtowners@...> Sent: Thu, Sep 22, 2016 9:13 am Subject: Re: [Amel Yacht Owners] Bonding Hi Pat. It sounds like your drive connection to the bonding system has failed. Do you have a prop zinc? On Kristy the connection to the bonding system is at one of the bolts on the housing at the top of the vertical drive shaft. Around -1000mv hull potential is correct for your boat. Your 804 (I assume really -804mv) reading indicates under protection of the whole system, so I would first check the connections between the strap and the rudder. I hope you'll find something there, as that would be the simplest thing to fix. If they are all OK, you'll need to check connections of the zincs to the rudder. Only way I know to do that is haul the boat out and check continuity from the zinc to the rudder post. I guess you could remove the zincs and wire brush the bolts and bottle brush the bolt holes with a SS or Brass brush if you can find one.
Let us know what you find.
Kent SM243
Kristy
How is the Cdrive & engine protected , if it not connected to the bonding system. With the silver anode the electrician had a reading over 1000 mv at the C-Drive, and at the strap 804. With the battery connection off, everything off it was 804 , with everything on ,still 804 . I suppose the 804 could be explain by poor zinc/bolt contact and the test being conducted in fresh water. If the engine is not grounded / bonded , how is it protected?
Thanks ,
Pat SM 123
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Patrick McAneny
Kent ,We put a large , massive zinc over the side , connected it to gen set and the number only went from-804 to -825. Would fresh water , opposed to salt water change the numbers expected , the electricians believed so . they said water temperature also affects it. I am going to buy a silver anode and spend some time on this.
Thanks,
Pat -----Original Message----- From: Kent Robertson karkauai@... [amelyachtowners] To: amelyachtowners Sent: Thu, Sep 22, 2016 12:33 pm Subject: Re: [Amel Yacht Owners] Bonding Pat, if the hull potential is different from the drive than from the engine and everything else, it isn't connected well to the rest of the bonding system. Normally you would see a better reading at the engine than at the drive. If you don't have a prop zinc, I can't explain the findings. If you have two problems, a bad connection at the rudder, and a bad connection at the drive, they would read differently. If you have a prop zinc it could be protecting the drive but the rudder zincs not protecting the rest of the boat.
Get in the engine room with your multitester and look for resistance between all bonded parts and the strap, including the rudder post. There should be essentially no resistance between all bonded equipment.
To check the zinc connection to the rudder, you have to haul the boat out and run a wire from the rudder post to the zincs and check resistance.
Does that make sense?
If not, please chime in!
Kent
SM243
Kristy
On Sep 22, 2016, at 11:58 AM, Patrick Mcaneny sailw32@... [amelyachtowners] <amelyachtowners@...> wrote: Kristy, Why do you think the drive connection has failed , if it shows Like -1000mv , I may have left off the - in my email , is that why? I guess the engine can be bonded to the zincs without being grounded ? I have no prop zinc , and don't understand how the strap and the Cdrive are so different in their reading.
Thanks ,
Pat
-----Original Message-----
From: Kent Robertson karkauai@... [amelyachtowners] <amelyachtowners@...> To: amelyachtowners <amelyachtowners@...> Sent: Thu, Sep 22, 2016 9:13 am Subject: Re: [Amel Yacht Owners] Bonding Hi Pat. It sounds like your drive connection to the bonding system has failed. Do you have a prop zinc? On Kristy the connection to the bonding system is at one of the bolts on the housing at the top of the vertical drive shaft. Around -1000mv hull potential is correct for your boat. Your 804 (I assume really -804mv) reading indicates under protection of the whole system, so I would first check the connections between the strap and the rudder. I hope you'll find something there, as that would be the simplest thing to fix. If they are all OK, you'll need to check connections of the zincs to the rudder. Only way I know to do that is haul the boat out and check continuity from the zinc to the rudder post. I guess you could remove the zincs and wire brush the bolts and bottle brush the bolt holes with a SS or Brass brush if you can find one.
Let us know what you find.
Kent SM243
Kristy
How is the Cdrive & engine protected , if it not connected to the bonding system. With the silver anode the electrician had a reading over 1000 mv at the C-Drive, and at the strap 804. With the battery connection off, everything off it was 804 , with everything on ,still 804 . I suppose the 804 could be explain by poor zinc/bolt contact and the test being conducted in fresh water. If the engine is not grounded / bonded , how is it protected?
Thanks ,
Pat SM 123
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Yes, Pat, salinity, temperature, and water flow can all affect the reading, although I don't remember exactly what happens under those circumstances.
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Kent On Sep 22, 2016, at 2:28 PM, Patrick Mcaneny sailw32@... [amelyachtowners] <amelyachtowners@...> wrote: |
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David Vogel <dbv_au@...>
Greets all, Regarding
the zinc on the prop, I've seen it mentioned that this is unnecessary
due to the AMEL-style bonding system, with everything bonded to
everything else. However, as I currently understand it, the reason for
the zinc on the prop, is because with a stainless prop shaft attached to
the dissimilar bronze of the prop, and because this is underwater, this
creates a galvanic couple. So, to minimise the potential effects of
this galvanic couple, it is best to place a zinc as close as possible to that underwater connection. And also, minimise the opportunity for adverse effects should there be a failure, or deterioration, in the bonding circuit between shaft -to- transmission -to- bonding-circuit -to- rudder-post -to- rudder-zincs connections. Happy to be corrected. However, in the interim, I personally would be placing a zinc on the prop/shaft to take all possible steps to minimise the potential for galvanic corrosion of the shaft or the prop. Best, David |
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When everything is connected and working as designed, I am sure that no prop zinc is required. However, when connections are loose/corroded and/or failures of equipment occur, severe damage can occur. My prop shaft was damaged severely by electrolytic corrosion due to a combination of misconnections of the bonding system and a fault in a charger/inverter. I will continue to use a prop zinc as long as I own my boat. Kent SM243 On Sep 23, 2016, at 10:44 AM, David Vogel dbv_au@... [amelyachtowners] <amelyachtowners@...> wrote:
Greets all, Regarding
the zinc on the prop, I've seen it mentioned that this is unnecessary
due to the AMEL-style bonding system, with everything bonded to
everything else. However, as I currently understand it, the reason for
the zinc on the prop, is because with a stainless prop shaft attached to
the dissimilar bronze of the prop, and because this is underwater, this
creates a galvanic couple. So, to minimise the potential effects of
this galvanic couple, it is best to place a zinc as close as possible to that underwater connection. And also, minimise the opportunity for adverse effects should there be a failure, or deterioration, in the bonding circuit between shaft -to- transmission -to- bonding-circuit -to- rudder-post -to- rudder-zincs connections. Happy to be corrected. However, in the interim, I personally would be placing a zinc on the prop/shaft to take all possible steps to minimise the potential for galvanic corrosion of the shaft or the prop. Best, David |
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David Vogel <dbv_au@...>
Greets all, Regarding
the zinc on the prop, I've seen it mentioned that this is unnecessary
due to the AMEL-style bonding system, with everything bonded to
everything else. However, as I currently understand it, the reason for
the zinc on the prop, is because with a stainless prop shaft attached to
the dissimilar bronze of the prop, and because this is underwater, this
creates a galvanic couple. So, to minimise the potential effects of
this galvanic couple, it is best to place a zinc as close as possible to that underwater connection. And also, minimise the opportunity for adverse effects should there be a failure, or deterioration, in the bonding circuit between shaft -to- transmission -to- bonding-circuit -to- rudder-post -to- rudder-zincs connections. Happy to be corrected. However, in the interim, I personally would be placing a zinc on the prop/shaft to take all possible steps to minimise the potential for galvanic corrosion of the shaft or the prop. Best, David |
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