anode bolts

[owen]

i am replacing my anode. it had been fixed with what appear to be mild steel bolts they were corroded inside but ok onb the outside.does anyone know what is recommended for this.
thanks in anticipation

 

[jerryat]

Think you'll find they're stainless steel but just look a bit rusty. Try cleaning off with a wire brush to check.

 

[alienzdive]

Replace with stainless steel.
Some people go to alittle extra trouble ot epoxy over the ends of the bolts to stop galvanic reaction between the stainless and the zinc. Theoretically the reaction will cause the zinc to disolve more around the bolts and fall off as the hole is naturally made bigger. But most people do not worry about this.

 

[boatmike]

They always used to be fitted with heavily galvanised mild steel bolts but the more modern idea is to use stainless steel. Either way you should either use properly designed bolts or double nuts, i.e. one nut to hold the bolt in place with sealant and a second nut to hold the anode on. that way if the anode corrodes away under the head of the second nut the hole won't leak water.

 

[tcm]

yep, epoxy or perhaps easier to get at later is a gloop of caulk/sealant over the bolt head.

 

[RMA]

I discussed this issue with a marine electrician who seemed to know what he was talking about - he advised against using stainless steel bolts. According to him stainless steel develops a coating when immersed in salt water which prevents proper contact between any bonding wires and the anode. If that is wrong I would like to know as I have a set of stainless mounting studs in the garage.

 

[jerryat]

Yes, I believe he is wrong, or at least hasn't thought it through very well. Most people will change their anode every three to four years (ok, I know some will be longer and some shorter!) and the mere act of doing this ensures that the nuts/thread contact is maintained.

The situation with mild steel ones is, I would suggest, a lot worse! Here, the corrosion on the hull 'plate' to which the anode strap is held, would require a lot of cleaning to make a good contact.

FWIW, I and my friends have used s/s studs for as long as we can remember, we regularly check the continuity of the connections, and have suffered no corrosion of any description on the equipment being protected. That's good enough for us!

I'd get the s/s studs out of your garage and onto the boat!!