puttingau wrote:
I have a lot of old zinc anode remnants from the boat hull hanging
around discards from the annual haulout. Each year I also replace the
anodes in my Yanmar 2qm20 engine, which are tiny, but more expensive
than the much larger tear drop hull anodes.
The engine anodes are just zinc molded on to a thread. Would it
difficult or in any way dangerous to melt an old hull anode down to
refurbish the engine anode?

If you can cast bullets you can cast something small of zinc, it is
done everyday. Large shipyards also melted & reclaimed big hull zincs
for decades. If you know nothing about casting & don't have the needed
supplies, don't bother. I know that people get raped on small
sacrifical anodes. Zinc itself isn't hazardous. Zinc is good for your
dink, some say. :-)