Sacrificial anode

[Dougy]

I have taken my boat out of the water for the first time, 22 foot lift keel sailing boat with inboard engine. I notice no anode anywhere, there doesn't seem to be any signs there has ever been one. Would there be a reason, does the boat need one.

 

[VicS]

I have taken my boat out of the water for the first time, 22 foot lift keel sailing boat with inboard engine. I notice no anode anywhere, there doesn't seem to be any signs there has ever been one. Would there be a reason, does the boat need one.

It only needs one if you can see any corrosion that might be prevented by fitting one.

You dont say what boat. and your profile gives no information

You dont say what engine. It may have one internally . See the manual.

 

[Dougy]

Hi and thanks, it is a seal 22 with a dolphin 12 HP inboard. Where is it likely to be if internal,

 

[VicS]

Hi and thanks, it is a seal 22 with a dolphin 12 HP inboard. Where is it likely to be if internal,

Yes a bit of Googling findsa PBO article on the Dolphin engines website which mentions the anode and stresses the importance of checking and replacing it

http://www.dolphinengines.co.uk/docs/PBO_ARTICLE.pdf

In fact two articles

Previous one http://www.dolphinengines.co.uk/docs/4.pdf

 

[Dougy]

Arrgh....I have visited said site and read the article from dolphin....scary!! Job has now been promoted to must do list...thanks for reply...

 

[Kwik Decision]

If you have a stainless steel prop shaft, and bronze prop, it is usual to fit a prop shaft anode to protect the prop from galvanic corrosion. How does your prop look? Any signs of pinkness or corrosion?

 

[Dougy]

Prop has been smothered in antifoul so looks OK. It is a 40 year old boat and prop looks its age. So maybe its internal?

 

[Dougy]

Oops!! Just realised the prop IS pink! I thought it was antifouled as the old antifoul was red...if its pink and not antifoul what needs to be done?

 

[omega2]

strike the prop and hope that it rings! scrape the shaft and hope you see shiny stuff, if not then contact they will put you straight.

http://www.clementsengineering.co.uk/stern-gear

 

[Dougy]

Many thanks, tintinnabulations needed and sought and preyed for!! Thanks for your help, off at first break in weather with a hammer many thanks again...

 

[Kwik Decision]

Prop has been smothered in antifoul so looks OK. It is a 40 year old boat and prop looks its age. So maybe its internal?

I guess if you use enough antifouling the prop will never come into contact with the sea, hence won't corrode! The internal anode VicS has highlighted in the engine is to protect the engine from corrosion, and is unlikely to do much for the prop. To work, an anode must be a) electrically connected to the part it is to protect and b) located close to it. It's obviously up to you, but for around a tenner, I'd fit one.....

http://www.asap-supplies.com/anodes/propeller-shaft-anodes

Sorry, very slow typing......
As Omega2 says clean it up, and hope its still serviceable. If it is, definitely fit a prop shaft anode.........

 

[Tranona]

An anode may not be needed. If it has lasted 40 years without one and the prop is still there, then doubt one is needed. at that age it might even be a bronze shaft or the prop is made of better material than today.

 

[Aja]

Don't hit the prop too hard! You just want to hear if it rings like a bell. A tap with a screwdriver will be enough

Regards
Donald

 

[Dougy]

Well thanks for all replies. Hammer put back in toolbox and replaced with screwdriver.... I agree, for the sake of a tenner I'll fit one even if the prop resonates beautifully...

 

[Dougy]

Yes I will fit one either way, hoping the pink or light red is antifoul and not corrosion and I hear a beautiful ping and not a disintegrating clatter.

 

[VicS]

Yes I will fit one either way,

A shaft anode will corrode away, being in close proximity and connected to a chunk of copper alloy with a relatively large surface area, whether it is doing anything useful or not.
It will therefore become a regular task, and expense, to replace it, not just a one off exercise.

As Tranona says if the prop has lasted 40 years without then it's doubtful if there is any need for anode.

If you do find that the prop has dezincified, then simply fit a manganese bronze replacement and you should be good for at least another 40 trouble free years.

 

[Tranona]

Well thanks for all replies. Hammer put back in toolbox and replaced with screwdriver.... I agree, for the sake of a tenner I'll fit one even if the prop resonates beautifully...

If i remember rightly your shaft emerges from a skeg, so you may not have enough room for a shaft anode. They are only suitable if you have a P bracket with exposed shaft forward of it. Do not attempt to put it in the gap between the bearing and the prop - that is there to allow water to flow into the bearing.