As an afterthought.

Taking a 50ft cat into a small harbour in bad weather could in itself be quite a demanding exercise.

A cat is lighter than both a mono sailing boat or a power boat.

In my very limited experience of a 9m Catalac they get blown about quite q bit even under engine, and even with twin engines were quite difficult to manoeuvre in a strong cross wind.

I can imagine a big cat in a crowded harbour in a strong wind being somewhat embarrasing

I think what I'm saying is don't jump out of the frying pan into the fire.

PPS

You mention Cat A for the boat, which reminded me. Lower categories of boat used commercially can only sail within specific distance of a "safe haven"

As this is legislation there must be some definition of what constitutes a "safe have"

From that it follows that whatever harbour, port or facility constitutes a "safe haven" must allow entry - otherwise it could not be a haven.

QED I suggest