Same problem - my solution!
I had the same problem with my Hunter 30. The original raw water intake on my boat was a tiny 1/2 inch ID thru hull mushroom covered with a round strainer cover. I had frequent blockages from the eel grass we have in Barnegat Bay , NJ. I replaced the thru hull and cover with a larger (3/4 inch) scoop strainer, with the slot openings facing aft. I also added an in-line raw water basket strainer and used 3/4 inch hoses throughout . This has made a huge reduction in eel grass fouling of the intake. In fact, in the four years since the modification, I have not have one event of eel grass fouling. But I know there is a island size mat of the stuff out there with my name on it.
