From recent posts, you can tell I'm on thinkin about the engine water
cooling system.

RECAP: I've got an inboard that is raw water cooled. The pump is a gear
type. The thru-hull is a scoop shape with somewhat of a strainer on it. It
looks basically like this...only bronze.

http://www.forespar.com/catalog/plumbing/scoop.htm

Question: Is this enough to keep junk like plastic bags from clogging my
water intake, or do I need something else?

My guess is that this is enough; that most things will either be big enough
to
just pass on by and anything small enough to get in will be chopped up
by the meshed bronze gears in the pump.

Thanks,
Gary