Had my best ever fouled prop this weekend on Carnarfon Bar - a white woven polythene sack (as used to pack potatoes) smothered the prop. Rope cutter couldn't touch it, and I couldn't free even from in the water. After being towed (these always happen whn there is no/too much wind) to Carnafon we mange to unwrap a thankfully undamaged prop.

To my mind this type of incident is perhaps even more dangerous as at least with a pot buoy a prop cutter stands a chance and if it doesn't at least you're already anchored!