Winterizing a non-starting Gray Sea Scout engine

[SURV69]

I'm trying to winterizing my Sea Scout(Port Clinton, Ohio).

The engine ran somewhat well during summer, although it always needed full choke and 15 or so seconds of cranking.

Now with the colder weather, it just doesn't want to start, and I find that the impeller is not enough to get the intifreeze into the engine.

I read that there might be drainage plugs, or petcocks to aid in emptying the raw water.

Any ideas to keep this engine from freezing?