Re: New VHF antenna = newly discovered electrical leak!


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

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