A few times that I've pulled the drain plug on my boat there has been red
fluid coming out. It happened again the last time I was out. The lake is
green and blue.

I took the engine cover off and inspected my power steering fluid level and
the power steering hoses with flashlight and by hand. No sign of leakage.

I ran the motor to operating temperature and turned the steering wheel a few
times; no sign of leakage.

Why do I occasionally get a red fluid coming out with the lake water when I
pull the drain plug after boating?

The only red fluid on the boat is the power steering fluid and gasoline.
The gas tank hoses are secure and there is no scent of gasoline, except
after dieseling.

Alpha One Mercury Mercruiser 4.3L V6 efi, approximately 45 engine hours
2005 Sea Ray 185 Sport