side vents for and aft on hull

[Bushwacker]

Mine has vents, big clamshell type made from Marinium on aft gunnel; stbd side faces forward, port side faces aft, with hoses leading down into the bilge. The later 20's had plastic vents in hull just forward of transom, similar to the 23's. The later I/O models, like Strick's 20' Sceptre had vents just aft of the engine box.