Where to place my shaft anode?

[Irish Rover]

My boat is on the hard for antifouling etc and I'm planning to replace the anodes - propellor, rudder and shaft. I took the old anodes off one side to source new ones and I marked the position by putting 2 cable ties at either end. I returned today to find the painters had removed the cable ties and the anodes from the other side in order to sand and paint. So now I'm wondering does it matter where I place the anode on the shaft? Stupid question, I know, but I'd rather ask a stupid question of the forum experts than find I'd made some stupidly obvious mistake when the boat is back in the water.

 

[Minerva]

My anode is probably about a hand width away from the p bracket. Never gave its exact placement much consideration really.

 

[B27]

I've always gone for close to the P bracket, but not so close as to impede water flow into the cutless bearing, so maybe 5 or 10mm gap.

 

[Tranona]

I've always gone for close to the P bracket, but not so close as to impede water flow into the cutless bearing, so maybe 5 or 10mm gap.

Correct but a bit more than that on a large shaft like that 15mm minimum.

 

[vyv_cox]

The basics of anode placement are in line of sight and as close as reasonable. As B27 says you don't want to obstructvwater flow through the cutless bearing, so about 25 mm from the P-brackets is good.

 

[rogerthebodger]

I fit mine half the diameter of the shaft forward of the P bracket to allow water flow

 

[Bouba]

I echo what everyone else says....close to the P bracket.....about a couple of inches or more away....in other words close to the things you are trying to protect

 

[Irish Rover]

Thanks for all the replies. Despite my son constantly telling to photograph everything before you remove it, I didn't. I'll measure the shaft tomorrow but I think it's probably around a 90/100 cm from the cutlass bearing to the P bracket and I'd say the anodes were fitted on both sides around ¹/³ distance from the P bracket or 30/35 cm from it. If I hadn't lost the markings that's where I would have refitted them. So I'm taking it the General wisdom is the go much closer to the P bracket.

 

[Bouba]

You don’t want them in the middle because that is where they can cause the most shaft vibration if the anode wears unevenly

 

[Bouba]

I always used lock nuts/nil stops instead of the regular nuts supplyed, after a long crossing with a loose one clattering into the P-bracket, mid winter Sardina to Barcelona is not the time for a quick dip to see what's going on.

I agree.....choose your anodes very carefully as well.....they are not precision machined and often the two halves don’t match....sometimes you need a few sets on the chandler’s shelf to find two matching halves

 

[vyv_cox]

I always used lock nuts/nil stops instead of the regular nuts supplyed, after a long crossing with a loose one clattering into the P-bracket, mid winter Sardina to Barcelona is not the time for a quick dip to see what's going on.

Use the two hammer method and they will.never come undone. Bang the two halves of the anode together with a hammer in each hand. Tighten the bolts. Repeat until the bolts will no.longer tighten.