In putting on the new hoses on the powerhead today,
it got me thinking more about “what” they all actually do.

In looking at my “before” photos and the Scott manual hose diagram,
I noted that the two hoses that plug into the two barbs on the
port side of the base, were “switched around”.
Not sure if that matters, but my Hiawatha parts motor matched
the diagram, so I installed the new hoses as such.

Anyway, from what I’m gathering from the diagram, I think I’m
seeing that the top main bearing hose (G) is draining to the carb
intake, and the center main hose (F) is draining to the powerhead
base, and that the Manifold Scavenging hose (E) is sucking from
the powerhead base into the one fuel pump port.
Is all this seem logical? My first outboard with a diaphragm carb,
and usually more modern of a motor that I mess with!

Given all the plumbing above, why is the hose / drain system
necessary on the starboard side of the motor, between the upper 
main and the powerhead base?
The Hiawatha parts motor with the same carb setup, does not
have this hose.

The whole nightmare of hoses……