If the centerboard tube is not wired to the ground bus, you can see voltage between that and the engine. That would make sense. In theory there should be 0 volts between the engine and the prop shaft. In practice, if you think about it, no part of the rotating mass of the engine can possibly be hardwired to the block or it couldn’t turn. There is oil and/or rubber seals between any part that turns and the block. Commercial vessels frequently use a carbon brush arrangement to connect the ground bus to the prop shaft. You also can loosen a prop bolt and make a jumper if the coupler is made that way where there is a nut on the backside. Another work around for this issue on powerboats is hull mounted zincs wired to the ground bus or you can get one of those zinc guppies and wire that to the ground bus when not underway. The mast voltage is ??? Is the mast grounded in some way or connected to underwater metal? My mast is connected to a keel bolt with 4 gauge wire. Joe Coquina
From: CnC-List [mailto:cnc-list-boun...@cnc-list.com] On Behalf Of Persuasion37 via CnC-List Sent: Tuesday, August 14, 2018 4:03 PM To: cnc-list@cnc-list.com Cc: Persuasion37 <persuasio...@gmail.com> Subject: Re: Stus-List [EXTERNAL] Re: Galvanic corrosion Joe I connected the ground from the multi-meter to the engine block. Then I took the positive lead and touched it against various pieces. Largest voltage shown was at the stainless tube for the centre board 0.25. The mast and prop shaft showed 0.02V Mike PERSUASION C&C 37 K/CB Long Sault On Aug 14, 2018, at 9:41 AM, Della Barba, Joe via CnC-List <cnc-list@cnc-list.com<mailto:cnc-list@cnc-list.com>> wrote: Voltage readings between what and what? Joe Della Barba Coquina
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