Prop Anode

[Sailfree]

Have a feathering prop and 2 anodes on shaft (1 for each year) and one tear drop anode on hull and all are corroding nicely. Intend to put a 3rd on shaft (other 2 appear sound around bolt positions, replace hull tear drop anode (all 12 months old and one 24 months) but just inspected prop anode and its dirty but untouched with no pitting (fitted 6 months ago).

What should the resistance be between anode & prop? I assume this will be same resistance between anode and shaft.

Will obviously check contact surface between anode and prop.

Would you replace prop anode with new or clean it up and reuse?

If you were to clean anode up how would you do it?

 

[DeeGee]

Hi Roger... If the anode shows no pitting, it probably isnt doing much work. That can be cos the resistance to that anode is much higher than that of the directly mounted shaft anodes. The resistance should be virtually unmeasurable with normal multimeters being too low.
I get a white deposit all over the anode, and that stops it working, cant remember what it is called, so I just change it.

Do your prop blades still ring when struck with a light hammer or spanner? If you remember I had a de-zinc'd prop, and it would just give a deadly thunk. /forums/images/graemlins/smile.gif /forums/images/graemlins/smile.gif

 

[FullCircle]

ooh, my blades give off a dull thunk.
But they are plastic Kiwiprop ones. /forums/images/graemlins/grin.gif

You can clean the oxides off the anodes, and remount it after cleaning all the possible contact to contact areas.

 

[VicS]

[ QUOTE ]
What should the resistance be between anode & prop?

[/ QUOTE ] There should be no measurable reistance (at least with an ordinary multimeter) between an anode and what it is protecting.

The suggested procedure for getting anodes clamped tightly on shafts it to do up the fastenings then wack the anode on one side with a good sized hammer while absorbing the shock with a good heavy dolly held against the other side. Then retighten the fastenings.

 

[Sailfree]

[ QUOTE ]

The suggested procedure for getting anodes clamped tightly on shafts it to do up the fastenings then wack the anode on one side with a good sized hammer while absorbing the shock with a good heavy dolly held against the other side. Then retighten the fastenings.

[/ QUOTE ]

Thanks for that.

It does have a white-ish deposit on it but not pitted and obviously not fully working.

I will follow above advise on refitting but did not just want to fit a new one without investigating WHY its not working. Only been on 6 months but prop blade did still ring.

Still not sure whether to clean the existing one up or fit new though? If to clean how? sandpaper?