Testing electrical connectivity

[Caladh]

I have had this pointed out in my survey -: Advisory Note: No electrical connectivity was established between the hull lozenge anode and stern gear. The propshaft has a brush assembly to create connectivity between this anode and the stern gear and this should be investigated.

I have changed the anode and bolts and cleaned up the brush assembly. How do I now test for "connectivity" and what am I looking for to make sure all is ok.

As an aside the engine is NOT connected to the anode (as on my previous yacht) with the brush connection the only one to the anode. There is also an anode on the rudder. All skin fittings and seacocks are now plastic and there is a flexible coupling between gearbox and shaft.

 

[Daverw]

Just check the resistance either side of the coupling, you are looking for a low figure, near zero

 

[pmagowan]

You use a simple circuit tester. Put one probe on the anode, the other on the bit you want to see is connected and it should beep

 

[Spyro]

You need a multimeter on ohms setting. One lead on the anode one on the stern gear. If the leads don't reach extend them. You should see a short cct or Low ohms reading if it's electrically connected.same as if you touched the leads together.

 

[VicS]

Just check the resistance either side of the coupling, you are looking for a low figure, near zero

If the connection to the prop shaft is made via "a brush assembly" ( such as MG Duff's "Electro-eliminator") connection across the shaft coupling does not come into it.

You need a multimeter on ohms setting. One lead on the anode one on the stern gear. If the leads don't reach extend them. You should see a short cct or Low ohms reading if it's electrically connected.same as if you touched the leads together.

+1

That is how to do it. Use the lowest ohms range, or the continuity buzzer if the meter has one

If the anode is-going to be effective it should be fairly close to the stern gear and the standard multi meter leads ought to be long enough.

 

[Heckler]

If the connection to the prop shaft is made via "a brush assembly" ( such as MG Duff's "Electro-eliminator") connection across the shaft coupling does not come into it.

+1

That is how to do it. Use the lowest ohms range, or the continuity buzzer if the meter has one

If the anode is-going to be effective it should be fairly close to the stern gear and the standard multi meter leads ought to be long enough.

Hesitate to contradict but sometimes in cases like this a bulb with some wires soldered on. Meters sometimes say yes when the contact isnt very good. A bulb load shows up bad connections.
Stu

 

[VicS]

Hesitate to contradict but sometimes in cases like this a bulb with some wires soldered on. Meters sometimes say yes when the contact isnt very good. A bulb load shows up bad connections.
Stu

When testing for a power supply couldn't agree more. A high impedance voltmeter can easily make a fool of you ( got the tee shirt!) and a bulb on a couple of leads is much more reliable .... Even better, a bulb with the meter in parallel.

For the case in point though I don't see any problem with the meter on a low ohms range. In fact it will tell you if there is a fraction of an ohms resistance somewhere whereas you might not see the effect of such a small resistance on the brightness of a bulb, esp out in the open in daylight. All mine have a resolution of 0.1 ohm on the lowest range.

 

[Caladh]

Thanks all - tested and at 0 ohms

 

[Ardenfour]

Slightly awkward to test for continuity with a bulb in this case. There is no voltage involved between abides and sterngear so bulb won't light anyway.

 

[RichardS]

Slightly awkward to test for continuity with a bulb in this case. There is no voltage involved between abides and sterngear so bulb won't light anyway.

I assumed Stu meant bulb + battery.

Richard

 

[VicS]

Slightly awkward to test for continuity with a bulb in this case. There is no voltage involved between abides and sterngear so bulb won't light anyway.

But if it does you have a problem in urgent need of investigation!