Although I have few elecrical gadgets to use power, I do worry about
having enough juice to run my VHF and running lights and am also
partial to having a small fan. Auto-pilot is also nice on long runs.
So what happens if my batteries accidently get run down? My old
Yanmar 1GM could be han cranked but my 2GM, no. However, while
looking into the engine compartment one day while under sail, I
noticed my prop shaft was spinning like mad cuz I hadnt put it in gear
(Yanmar says put it in reverse). So: maybe not so useless Idea #3727


Can you release the compression of the engine with the decompression
levers, get going good under sail with engine in gear an use the
spinning prop to sorta "push-start" the engine with you suddenly
giving it compression? I might try this next time I am out.

For that matter, I have heard of these spinning things you can drag
behind to generate power but I can imagine getting it caught on a crab
trap or something or having its line wrap round your prop. So, why
not put a v-belt pulley on the prop shaft and use it to turn a belt
attached to another alternator. This way you could charge your
batteries without starting the engine (sure it slows you down some).
This cannot be original cuz I know I saw it somewhere but cannot
imagine where.