What is it?

When you look at a boat, it can be so confusing. Not only is the terminology so different, for example port instead of left, bow instead of front, head instead of toilet, but there are so many physical objects and terminology that are different. Take for instance this.....

 

It is on the starboard aft side of the hull and it baffled me for a couple of days. Then it came to me today that it was a strainer for the raw water intake. It stops seaweed and debris from clogging up the hoses. I think that the engine cooling system is self contained so it is probably for the kitchen sink. Another object that still defies description is on the port side.