Cabin height
Those specs won't give you what you need. 9'9" is the "J" value, or the distance from the mast to the bow. "I" is the jib luff (forestay) "P" is the main luff (height) "E" is the main foot. (along the boom) Nevertheless, having just extensively measured my 1990 Hunter 30 (identical to '89/30) for a new main sail, I might be able to help you. From the waterline to the top of the mast is 50' Draft (waterline to bottom of keel) is 4'3" So bottom of keel to top of mast is 54'3" Maximum Halyard hoist to deck is 44'1". Add 8" to reach the top of the masthead (the halyard doesn't hoist the mainsail to the very top of the mast), so top of mast to top of cabintop is 44'9" Therefore bottom of keel to cabin deck at the maststep should be 54'3" less 44'9" or approximately 9'6" Hope this helps you get your quote.
