Will I need a zinc anode?

[Matthew]

Hello,
I am thinking of adding a cast aluminium centreboard to our 17ft daysailer. She is grp construction, but has some bronze rudder gudgeons.
If she is left at a mooring all season, would the centreboard get eaten, given that the bronze and aluminium are about 6 foot apart and not electrically connected?
The boat has no other electrical systems.
Many Thanks,
Matt

[Corpus Skipper]

Why aluminum? Wouldn't glass or glassed over wood be much cheaper and easier?

[Ilan Voyager]

In theory you won't need an anode. Practically maybe a small one as some times aluminium has its mysteries.

But why aluminium? it's not a good choice for a foils: it's heavy and bends too easily.

As it has been said before glass, epox and wood are far better for this use: more resiliency, and ability to dissipate overloads.

[Matthew]

Thanks for your replies. I thought since it is much higher up the table than bronze, that it would get eaten, but does the fact that they're not electrically connected (except by salt water) mean it will be okay?

Why Aluminium? It needs to be heavy enough to sink easily, so that only a pull up pendant is needed (rather than a pull down one too, as would be the case with epoxy and glass, unless you had lots of glass, which I guess is an option). We could add lead into the board but the more processes like these, the more time it takes and costs go up.
It also enables us to easily reproduce a NACA section, since it is cast, and we have access to a low cost "casting person".
I am worried about the strength though.
Do you know how other mass and semi-mass producers make their centreboards?
I want to avoid a galvanised steel plate if possible since it isnt to good at generating lift apparently. Does anyone have any practical expreience to bear this out though?

Thanks for your input,
Matt