That is a work of art right there. Sending that to my service guys to copy. You don't own the patent do you?
Nah, I wish I could get a patent by drilling a hole on a lid and sticking a valve on it! PS: by the way, I like salt water to stay outside ALL of my boat, not only main engines. For the genset, the a/c chiller and the shaft seals, I made a modification which makes flushing even easier, because they are all directly connected to the boat fresh water circuit, so I can feed all the bits that require salt water also with fresh water, just by turning two valves. The reason why I didn't do the same also for mains is just because I feared that the flow from the boat fresh water pump might have been not sufficient. But in hindsight, maybe it was... I just can't be bothered to modify it again - the above solution is quick and easy enough for me!