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New VHF antenna = newly discovered electrical leak!

Scott SV Tengah
 

I’ve had VHF reception and transmission problems and recently replaced my original VHF antenna with a Shakespeare 5215. The male connector threads fit perfectly where the old antenna sat on the masthead, obviating the need for drilling new holes for a mounting bracket. In addition to replacing the antenna, I replaced the outrageously thin RG-58U original coax to lower loss RG8X. There are even thicker and even lower loss cables out there but the thicker cables have minimum bend radii that I’d violate given the routing through the mast so RG8X was my compromise.

 

I’m not sure if it was the cable or antenna, but my VHF problems were solved and I can now hear and be heard from a much greater distance than before!

 

However a new issue came up. Because of the way the male connector threads contact the mast, the coax shield effectively connects the mast/rigging to the VHF head unit and the head unit grounding wire then connects it to the bonding system. With this connection made, the Mass- light lit up, indicating an electrical leak! If I disconnected the grounding wire from the VHF head unit body, the mass- goes away. 

 

It turns out I had an electrical leak going through my rigging for a while now. The evidence was there - rust spots all over the rigging/liferails and some higher than expected (sacrificial?) corrosion on aluminum parts. Per Olivier, it turns out Amel started connecting the mast/rigging to the bonding system around 2009 for this exact reason - an undetected electrical leak in the rigging with boats that don’t get washed often could lead to electrolytic corrosion. 

See: https://amelyachtowners.groups.io/g/main/message/21220?p=,,,20,0,0,0::relevance,,Olivier+rigging+bonding,20,2,0,29761258

 

I would suggest those of you with pre-2009 Amels test for either negative or positive charge through your rigging. If you have a mass tester light and are pre-2009, it will NOT light up unless you make a connection between your rigging and green/yellow bonding system wires. I would think a simple way to make that connection is a temporary jumper wire between the rigging and say the green/yellow wire at your diesel fill-up.

 

I isolated the leak to my starboard Lewmar V4 windlass motor. It’s the primary one, so I presume age has resulted in carbon brush dust buildup. I assume cleaning it simply involves taking it apart and blowing/wiping away excess carbon dust? Any tips or warnings before I dig into it?

--
Scott 
2007 A54 #69
SV Tengah
http://www.svtengah.com

Sv Garulfo
 

Hello,

We have a similar issue with our VHF and haven't so far figured out if due to antenna or cabling. (measure of the impedance between the core and shield of the existing system returns a infinite value)

How easy was it to run the new coax cable? What cable length did you get? Is there a dedicated gulley for that cable? Did you find the old cable was damaged by chafing?

On Garulfo, we know the rigging is connected to the bonding system, which we confirmed when tracking a mass leak last year.

As per your mass leak, carbon dust can be the reason for it.

Thomas & Soraya
Garulfo A54-122
Marquesas, FP

On Wed, 20 Nov 2019 at 03:17, Scott SV Tengah <Scott.nguyen@...> wrote:

I’ve had VHF reception and transmission problems and recently replaced my original VHF antenna with a Shakespeare 5215. The male connector threads fit perfectly where the old antenna sat on the masthead, obviating the need for drilling new holes for a mounting bracket. In addition to replacing the antenna, I replaced the outrageously thin RG-58U original coax to lower loss RG8X. There are even thicker and even lower loss cables out there but the thicker cables have minimum bend radii that I’d violate given the routing through the mast so RG8X was my compromise.

 

I’m not sure if it was the cable or antenna, but my VHF problems were solved and I can now hear and be heard from a much greater distance than before!

 

However a new issue came up. Because of the way the male connector threads contact the mast, the coax shield effectively connects the mast/rigging to the VHF head unit and the head unit grounding wire then connects it to the bonding system. With this connection made, the Mass- light lit up, indicating an electrical leak! If I disconnected the grounding wire from the VHF head unit body, the mass- goes away. 

 

It turns out I had an electrical leak going through my rigging for a while now. The evidence was there - rust spots all over the rigging/liferails and some higher than expected (sacrificial?) corrosion on aluminum parts. Per Olivier, it turns out Amel started connecting the mast/rigging to the bonding system around 2009 for this exact reason - an undetected electrical leak in the rigging with boats that don’t get washed often could lead to electrolytic corrosion. 

See: https://amelyachtowners.groups.io/g/main/message/21220?p=,,,20,0,0,0::relevance,,Olivier+rigging+bonding,20,2,0,29761258

 

I would suggest those of you with pre-2009 Amels test for either negative or positive charge through your rigging. If you have a mass tester light and are pre-2009, it will NOT light up unless you make a connection between your rigging and green/yellow bonding system wires. I would think a simple way to make that connection is a temporary jumper wire between the rigging and say the green/yellow wire at your diesel fill-up.

 

I isolated the leak to my starboard Lewmar V4 windlass motor. It’s the primary one, so I presume age has resulted in carbon brush dust buildup. I assume cleaning it simply involves taking it apart and blowing/wiping away excess carbon dust? Any tips or warnings before I dig into it?

--
Scott 
2007 A54 #69
SV Tengah
http://www.svtengah.com

Scott SV Tengah
 

Thomas, 
 
Sorry for the slow reply. Infinite resistance just means the core and shield are not shorted out. The original antenna does not have a removable connector on the antenna side. I had to cut the coax wire at the antenna. I believe water must have gotten inside either the antenna or coax as the shield showed some signs of corrosion. 
 
I then taped the new coax (RG-8X) to the old coax and had someone pull it down from the starboard side base of the mast. Quite easy but there is a somewhat sharp bend at the bottom - be careful not to damage the coax or bend it too sharply. I believe RG-8X requires a 10cm bend radius. Then it's easy to run it into the boat using the access panel above the door between the saloon and the bunk bed area. There is a mousing line inside the mast, but I didn't use this. The reason is that I didn't want to pull raw coax up and then have to do the termination soldering "in the air" at the top of the mast. By using the old coax to pull the new coax down, you can do the antenna side termination "on the ground" and pull raw unterminated coax down through the mast and terminate it "on the ground" once you determine the right length.
 
I didn't want to leave anything to chance, so I ran new coax all the way to the VHF. That part was a bit more difficult but luckily the coax is not zip tied to the wire bundles on the starboard side. A little pushing and pulling and we got new wire all the way to the VHF. 
 
I got raw coax so you will need to terminate them yourself and weather seal the termination at the antenna side. I watched some youtube videos - not difficult at all. Get the quality soldered terminals, this is not a place to be cheap.
 
There is a coupler inside the access panel above the door that allows you to disconnect the coax in case you ever need to remove the mast. I did not install this because I believe each additional termination is an opportunity to screw up. If, in the future, I need to remove the mast, I can then add those additional terminations and use the coupling.
 
I got about 42 meters of RG-8X coax. I have lots left over after the VHF antenna install, but I plan to replace the mizzen AIS antenna and coax at some point.
 
On the mass-neg leak into the rigging, I've measured it to be about 150mA. I disconnected everything in the main and mizzen and it still exists. I am certain it's something in the bow locker. Sadly, I disconnected both windlasses, both genoa/staysail Bamar boxtron units and the leak seems to still be there. I fear it may be a chafed wire somewhere in the bow locker. Not looking forward to finding it.
--
Scott 
2007 A54 #69
SV Tengah
http://www.svtengah.com

Sv Garulfo
 


Hi Scott,

Thanks Scott for your answers for the VHF. A friend tipped us to use uncut cable ties every foot or so, at say, 120° angle from each others as chaff guards along the mast. Would that be useful/possible in our case?


For the leak, try the bow thruster, ours was located there because of carbon dust. Also try the navigation lights, we had a small leak there too. 

Undo the cables one by one until it disappears, but the following can be confusing: 
If you have 2 locations for leaks, you can think an equipment is ok because you unplugged it and the leak is still there. So in theory, you should unplug everything and test each equipment one by one by replugging just that component. It’s a lot more work and best done starting from the battery bank to isolate the part of the boat the leak is from. But even that can be confusing because the leak from the bow thruster can be seen in the console section through the command part of the system (the joystick activating the relay). Ask me how I know. 

What may help you:
I wired a leak detector that i could use where I was working rather than shout at Soraya for testing with the amel built in tester. It’s a simple  LED bulb and 2 long wires. I connect one side to the positive (for testing a neg leak) nearby (but live) and the other to the bonding system, for instance the rigging, the guard rail etc. If there is a leak (ie the neg is connected to the bonding system somewhere), the bulb lights. And even better, the quantity of light shows the intensity of the leak. That’s useful for sorting big leaks (for us the truster) from small ones (for us, the navigation lights). 

Hope that helps, good luck. 



On Sat, 30 Nov 2019 at 08:51, Scott SV Tengah <Scott.nguyen@...> wrote:
Thomas, 
 
Sorry for the slow reply. Infinite resistance just means the core and shield are not shorted out. The original antenna does not have a removable connector on the antenna side. I had to cut the coax wire at the antenna. I believe water must have gotten inside either the antenna or coax as the shield showed some signs of corrosion. 
 
I then taped the new coax (RG-8X) to the old coax and had someone pull it down from the starboard side base of the mast. Quite easy but there is a somewhat sharp bend at the bottom - be careful not to damage the coax or bend it too sharply. I believe RG-8X requires a 10cm bend radius. Then it's easy to run it into the boat using the access panel above the door between the saloon and the bunk bed area. There is a mousing line inside the mast, but I didn't use this. The reason is that I didn't want to pull raw coax up and then have to do the termination soldering "in the air" at the top of the mast. By using the old coax to pull the new coax down, you can do the antenna side termination "on the ground" and pull raw unterminated coax down through the mast and terminate it "on the ground" once you determine the right length.
 
I didn't want to leave anything to chance, so I ran new coax all the way to the VHF. That part was a bit more difficult but luckily the coax is not zip tied to the wire bundles on the starboard side. A little pushing and pulling and we got new wire all the way to the VHF. 
 
I got raw coax so you will need to terminate them yourself and weather seal the termination at the antenna side. I watched some youtube videos - not difficult at all. Get the quality soldered terminals, this is not a place to be cheap.
 
There is a coupler inside the access panel above the door that allows you to disconnect the coax in case you ever need to remove the mast. I did not install this because I believe each additional termination is an opportunity to screw up. If, in the future, I need to remove the mast, I can then add those additional terminations and use the coupling.
 
I got about 42 meters of RG-8X coax. I have lots left over after the VHF antenna install, but I plan to replace the mizzen AIS antenna and coax at some point.
 
On the mass-neg leak into the rigging, I've measured it to be about 150mA. I disconnected everything in the main and mizzen and it still exists. I am certain it's something in the bow locker. Sadly, I disconnected both windlasses, both genoa/staysail Bamar boxtron units and the leak seems to still be there. I fear it may be a chafed wire somewhere in the bow locker. Not looking forward to finding it.
--
Scott 
2007 A54 #69
SV Tengah
http://www.svtengah.com