Instead of a syphon break on the engine, I have fitted a vented loop.
A vented loop IS a siphon break/anti-siphon device. And putting a vent line on it instead of an air valve is a very BAD idea! As you've noted, it's a very small hose...only 3/8" (which I suspect is the OD because the nipple on the top fits the ID of a 1/4" hose.), so the same sea water minerals and salt that you don't want to clean out of an air valve quickly clog up the connection. But because it's solved any squirting problem it becomes pretty much "out of sight, out mind"... turning your vented loop into an UNvented loop that no longer has any ability to break a siphon.