Its interesting because the maser of a privately owned boat/ship is obliged but it states nothing about the harbour.

The situation seems as I thought it was - regs applying to boats but the rest is not clear and relies on common sense not law ...... so my guess is that here is no specific law.

This means I have a weak case arriving in a little Cornish harbour two hours before the storm hits and whilst it is still calmish with a big cat and making sure I can stay there