I need a good weed fin for the shallow, weedy water that i sail. I just have no idea where to start. I normally sail with 6.5>4.7 sails on my 80L slalom board and i want to start getting into gps speed sailing. I don't really know where to start though.
What makes a good fin?
What sort of fin should i be looking at? (i definitely need a weed fin though)
Why are some called freeride, other slalom, other speed? What do the names mean?

Any help would be really good.
Cheers.