They were helped to safety at high tide on Saturday night.
They're stuck in shallow, muddy water in a remote part of the peninsula.
The fraying on the rope indicated it may have snapped.
Choppy seas are preventing the Coast Guard from helping the ship.
"What we're seeing around the whole country is the failure of Government."
"Just seeing this big shark's head clamped over the front of my board, its massive head there with its eye looking back at me."
The man managed to make it to shore safely - but his board took a bite.
It's not clear how long the plant was in place.
A group of fishers in Thames are accused of under-reporting 20 tonnes of fish.