R + D Coupling Earth Bonding

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KAM

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I have been attempting to earth the coupling but I don't like the idea of the silver impregnated rubber strip which is recommended as I can't see how it can provide a good contact. I attempted to use a copper braid with crimped ends connected to each side of the coupling but this failed part way through the season. I assume it must have fatigued due to vibration and centrifugal loads. Has anyone solved this problem.
 
The way I electrically bridged the doughnut is by using a bit of stainless steel wool, culled from a pan scourer. Just stuff it in the centre of the couplings so it is against the metal strapsof the doughnut and Robert is your mother's brother.
 
michael_w said:
The way I electrically bridged the doughnut is by using a bit of stainless steel wool, culled from a pan scourer. Just stuff it in the centre of the couplings so it is against the metal strapsof the doughnut and Robert is your mother's brother.
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Would it be possible to fit a spring in there? Seems so obvious that there must be some reason why not.
 
Any problems with corrosion. The straps in contact with the silver or stainless are just zinc plated steel. I would have thought the connection would need to be fairly low resistance to get full benefit from the anode.
 
What sort of wire and terminals. I tried a braid and standard yellow crimp rings. It broke after about 50 hours. I was thinking of soldering but it usually stiffens the wire too much. Maybe the braid was too flexible and moved too much.
 
KAM said:
What sort of wire and terminals. I tried a braid and standard yellow crimp rings. It broke after about 50 hours. I was thinking of soldering but it usually stiffens the wire too much. Maybe the braid was too flexible and moved too much.
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I'd have to look to be certain, but IIRC, a short length of multi-strand insulated copper wire, around 10swg, with 10mm, (bolt size ) yellow sleeved terminals.
I usually pull the sleeves off, lightly crimp the terminal onto the wire with pliers, solder and refit the sleeve, the hot metal makes the sleeve more flexible. I find a small butane blow-lamp handy, the quick, localised heating minimises solder flow along the wire.
This bridge noticeably increased the rate of anode erosion, and the new propellor I fitted at the same time shows absolutely no sign of corrosion, unlike it's predecessor.
My 3-cyl. engine probably gives the coupling a fairly easy time.
 
Thanks earlybird thats very helpfull. I have just found two heavy duty 10mm terminals so I will try crimping and soldering this time.
 
I did a similar contraption to Earlybirds about 3 years ago. Still Ok and that's on a 1 pot Yanmar so a bit bouncy. It's not as tho I'm a purist sailor either - engine on quite a lot.
 
Mine has a crimp terminal at one end which is on one of the bolts on the coupling, and the other end is held onto the shaft using a jubilee clip. The rotation of the shaft broke various parts of the versions before this one.
 
KAM said:
I attempted to use a copper braid with crimped ends connected to each side of the coupling but this failed part way through the season. I assume it must have fatigued due to vibration and centrifugal loads. Has anyone solved this problem.
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Yes - ordinary copper wire just as you tried. The centrifugal loads are trivial but if you have sufficient lateral movement to fatigue the copper then you should do something about the alignment anyway. The coupling helps to minimise vibration from any misalignment but that doesnt mean you should tolerate misalignment.
 
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