I own a 9.2a Hull # 433, the water heater is removable, Woodster is correct. Remove the siide fill piece/shelf, than the table holder if you have one , than the screws that are at the bottom of the buldhead. The upper port side affords a hand hold to pivit the balkhead away from the hull. This ia also a good time to maintain the bilge pump.
In 1988 I almost replaced the water heater only to find the plastiic plug for the optional heat exchanger was leaking. The fix was to replace the plug with a standard brass clean out plug.
This season fix is to reanchor the water heater with new angle braces.