The water marks on the harbour entrance walls show the huge tidal range at this part of the Bristol channel, a large view may show this better,

Entry is not possible to the harbour in strong onshore winds. Be very aware that there is a tidal range of 10 metres at Springs and 5 metres, at Neaps, ( from Mariners notes)

This is the second or third highest tidal range in the world!

HWW! and nice second half of the week!