From all the pictures I see of Catalina 30 MKIII’s, there’s a lot of space between the shrouds and the lifelines. That’s where the clew of the sail should be - outboard of the shrouds and inboard of the lifelines. This is true of many masthead rigs with large headsails. Upwind the trim angle should be acceptable because the shrouds are far enough inboard. Downwind the sheet might touch the lifelines a bit but no significant interference.
Fractional rigs are a different arrangement and often have smaller headsails sheeted inside the shrouds. Usually the shrouds on those rigs are further outboard. By sheeting inboard of the shrouds the upwind trim angle can be a little closer. Usually these types of rigs are put on boats that can take advantage of the tighter sheeting angle - sheet a jib too tight with a 150 sail on a heavy displacement boat and you’ll lose more power than the designer intended.
Fractional rigs are a different arrangement and often have smaller headsails sheeted inside the shrouds. Usually the shrouds on those rigs are further outboard. By sheeting inboard of the shrouds the upwind trim angle can be a little closer. Usually these types of rigs are put on boats that can take advantage of the tighter sheeting angle - sheet a jib too tight with a 150 sail on a heavy displacement boat and you’ll lose more power than the designer intended.
