February 6, 2022 – a near real-time post.
We took advantage of our weather-mandated stop in Tauranga to haul out at our favorite NZ boatyard for a bottom job.
We also needed new anodes. This was a bit of a problem in that we had no prop anodes left on board. We’ve been using an anode made from a metal called Maddox since we’ve first came to NZ. We usually order them from Australia but shipping is sporadic lately. Solution: Make them!
First I printed a plastic plug in the shape I wanted…
Next, off to one of the local foundries to have it sand cast from the metal from a larger, melted Maddox anode that is readily available here.
The casting cost $80 NZ (his minimum charge) and he made us six anodes. I printed six plugs so he could pour them all in one go. There are small, round Maddox anodes available (as pictured in the link above), but I think that I saved about 50% of the cost of these anodes by making my own and more importantly, was able to get them when I needed them.
Next, drill and tap. I thought this was going to be hard with gummy soft metal, but it was actually really easy.
And the finished product…
I don’t know if melting the metal will have any significant effect on its anodic properties. Only time will tell. I’ll keep a close eye on it for a while.
We also put a big Maddox anode on the hull…
The reason the prop needs its own anode is that it’s a feathering prop and the end floats in grease and doesn’t have a good electrical connection to the prop shaft which is bonded through a shaft brush.
We got two years out of the last set of anodes. Maddox has been amazing! -Rich
Update: August 15, 2023
Here’s the new cast maddox anode after a year and a half in the water. There’s still much more than half of the material left. I’m sure two years would have been no problem.
