[Chicago Big Kahuna]

I am new to SH4 and am looking to get some basic info on the different speeds of ships and the sub itself. For example, in attempting to intercept, when a ship is going "slow" "medium" "fast" what does that mean in knots? Same for sub? Is there a tool that helps specify/makes it easier to determin what half degrees are when using the protractor to plot courses (i.e. NNE, etc.)

Thanks for the help