Clamshell facing aft
This same topic comes up from time to time and the subject of which way to face a sea-water clamshell strainer goes around and around. I installed an aft facing clamshell strainer on both of the boats I have sailed over the past 15 years. I sail mostly in the Barnegat Bay region of New Jersey and there is a significant amount of eel grass. Before the installation, I had a real problem with the eel grass and engine overheating. Since then, I have not had one incidence of eel grass clogging the engine or strainer. At the end of each season, with maybe 150 hrs of engine use, I rarely find one or two pieces of eel grass in the engine raw water filter. I do try to steer around the large floating islands of grass when I see them.