Earth continuity and anode problem

[SpiderDiver]

After changing all anodes on my Princess 360 today, checked the earth continuity between shafts and main anodes. Found no connection between prop shaft and main anode on stbd side - good connection on port side.

Question is where does drive shaft get it's earth from, the stern gland housing or the p bracket?

 

[pvb]

Probably from...

Probably from the engine. The stern gland and P-bracket won't have metal-to-metal contact.

 

[VicS]

Carbon brushes running on the shaft? Thats about the only really reliable way.

 

[boatmike]

Probably through the engine block. Check connections across flexible couplings and clean any connections from the engine block to the anode

 

[SpiderDiver]

Had checked engine block out Ok so problem must be couplings which appear to be fully isolated (on both sides) and no brush arrangement or anything? Unless there is something integral to coupling that is broken? /forums/images/graemlins/confused.gif

 

[boatmike]

Look carefully. There is often a flexible metal strap across the coupling. Either way make metal to metal contact between gearbox flange and shaft (jump lead?) and see if this cures your problem.

 

[SpiderDiver]

Thanks for all your good advice - now know where the problem lies. /forums/images/graemlins/smile.gif