As for whether the hooknife can be effective in cutting the line without taking a dive, it depends on how far away the line
is in relation to the *length of the boat hook* which the knife is attached to. Obviously, this will also vary with the keel/
rudder/prop configuration.

The problem with your proposed method is that even if successful, some of that line is still caught. With a knife you can
(potentially) cut all of the remaining line. It's true you can continue to sail and sort it out later - IF there is wind enough
to sail and IF your destination doesn't require you to enter under power.

Jerry