It's just a strainer on the outside of the hull covering the thru-hull opening. There's no place for anything to catch there. That said, when we were stationary with the engine idling we once lost water circulation. Apparently a jelly fish (or else a plastic bag) splatted on top of the strainer and blocked it. But we simply turned off the engine, it drifted off, and we restarted the engine. When underway it would be pretty unlikely for that to happen. As I said we've never had an issue in 11 years except for that one incident.