MadKeenMatty. I always thought tidal coefficient means the movement between tides. As in the difference between how far the tide goes out and how far it comes in.
For example if on a spring tide during full or new moon the high tide is very high, and the low tide is very low, it might have a tidal coefficient of 118. During last or first quarter the tidal coefficient might be as low as 48. This means it will be a very low tide and a very high tide during that particular spring tide, and very little difference between high and low during that last or first quarter tide. For the most part it may not actually have a lot to do with currents, but more to do with a rapid rise and drop at the top end of a high tidal coefficient. At least that's how I understand it.
Its a useful tool when deciding whether or not to go to that one spot that is easily accessible at a low tide, but dodgy during a very tide.