A good resource....
... is John Heyes' "Winning Races". Chapter 8 has a detailed discussion on crew selection and their organization, positon by position. Numbers of crew positions needed for various boat sizes are suggested. For instance:Boat size 30 ft, Total crew 6Positions bow, mast/pit, 2 trimmers, mainsheet, helm/tactician.boat size 35 fttotal crew 7Positions bow, mast/pit, 2 trimmers, mainsheet, helm, tacticianboat size 40 fttotal crew 8Positions bow, mast, pit, 2 trimmers, mainsheet, helm, tactician.If you have runners, the tactician would cover that duty.