ROPE AROUND THE PROP?
This can happen to all of us at times. Sometimes it may be a rope that you have aboard but more often it is likely to be a crab pot rope or a fishing line. You usually have no choice but to dive on the prop and try to free the line.
Hacking away with a knife underwater is very difficult and time consuming. A far better option is to use a hacksaw to free the prop rapidly. The hacksaw easily cuts through rope. You will be amazed at the difference.
Use a decent full size hacksaw, not one of those junior hacksaws. When you have finished wash it in fresh water and give it a coating of dewatering fluid or oil to prevent corrosion.