called that I've seen some of the lads using on the boat during a recent boat competition? I called it an apron but Mr google or Mr E-Bay doesn't agree with me 
It has pockets facing the angler suitable for holding knife/ T-bar/ rigs/ etc etc and It Attaches to the hand rail of the boat. Hope someone can put the proper name on this for me so that I may buy one.Cheers
Dave