Rate of anode corrosion

[rafiki_]

Any wise heads out there with experience of slowing down galvanic corrosion. My boat has been in freshwater about 12 months and the leg anodes all need replacing. Any way to decrease the rate so the boat can stay in for 3 years?

 

[buster3]

galvanic isolator may help if your on shore power all the time

 

[hlb]

Get some stainless steel ones.

 

[pissativlypossed]

Ignore the stainless steel answer, you want your anodes to dissolve, this means they are working as designed. Galvanic isolator will help if on shore power, if not try hanging an anode over the stern, it will have to be bonded to the anode circuit first though.

 

[hlb]

He said he wanted the anodes to last longer, nowt about his engines or boat.

 

[Bilgediver]

Any wise heads out there with experience of slowing down galvanic corrosion. My boat has been in freshwater about 12 months and the leg anodes all need replacing. Any way to decrease the rate so the boat can stay in for 3 years?

Do you have rubber bushed props??

 

[carlton]

It sounds as though your anodes are doing exactly what they're supposed to. The only way to extend the boat's stay in the water would be to fit additional anodes.

 

[nonitoo]

Any way to decrease the rate so the boat can stay in for 3 years?

In a word - No.

Tom

 

[pissativlypossed]

Trust You

Get some stainless steel ones.

I should have realised, your far too clever for me.

 

[rafiki_]

While I quite like the idea of stainless steel anodes, I think the longevity of the powertrain will suffer as a consequence, so I'll go for the Galvanic Isolater idea. Any useful links?

 

[Sy-Revolution]

I bought one recently from these people:

http://cgi.ebay.co.uk/Own-a-boat-Yo...UK_Sporting_Goods_Sailing?hash=item2a023401b9

Larger capacity for the same price as a sterling 30amp, seems well enough made. Comes with comprehensive installation instructions and blurb.

Good service too.

No connection etc.......

 

[buster3]

try www.safeshoremarine.com or www.galvanicisolaters.com very helpful

 

[Tranona]

A galvanic isolater is only useful if you are permanently attached to shorepower. 12 months is not an unreasonable time for anodes. Make sure you are using anodes suitable for fresh water.

I think you just have to accept that with such a mix of dissimilar metals anodes are essential and better to replce them than the bits they are protecting.

 

[rafiki_]

Thanks for this. Will follow up the links.

 

[KevB]

What I'd give for my anodes to last 12 months. 5 if I'm lucky...

 

[rafiki_]

I have heard that an isolator will not be much use on a plastic boat. They work better on a steel hull. Any thoughts?

 

[enterprise]

Althought the stainless annodes recomendation was in part a joke, hlb was hinting along the right lines.

Try alluminium annodes instead of zinc, they are available from performance metals.
We have two sets fited to our Volvo 290dp outdrives.
They were recomended as we fitted stainless duoprops, the rate of errosion on the zincs accelerated and we wanted incressed protection without the 6 month liftout, been on now for 6 months and are only 20% worn, will replace them while out for the winter as we intend to stay afloat for 2 seasons from next April.

http://www.performancemetals.com/default.asp

 

[whisper]

Our zincs normally last just 4 months and we are not on shorepower. Have now fitted aluminium ones in certain places and will see if that makes any difference. Another advantage of aluminium ones is that they are far lighter than zincs so it's quite ok to fit larger sized ones on, for example, trim tabs.

 

[gjgm]

I m a bit of a thicko on this...presumably you are trying to protect the leg/props via an anode. So if you use an anode that doesnt disappear as quickly... well, is that improving the protection of the valuable bits.. or just the £30 anode?

 

[hlb]

This whole idea seems counter productive, even if three years could be achieved by extra anodes or what ever. Hence the SS suggestion. The reasons for taking the boat out at least once a year are many. Mainly to stop problems getting to sever before correcting. I took the boat out after about six months this year, only to find one anode was missing. Then later found the grounding had come off also. Hopefully I have arrested the problems in time. But not sure I'd have a drive left in three years.