I'm not sure but on a 93-46 it is on the starboard side forward of the engine room. My access is through a hatch next to the steps going down to the galley beside the central vacuum system.
Weldcrane, Can you please be more descriptive with your titles? It's very helpful for other members doing searches on YF, as well as indexing in search engines. You'll get a better response to your questions. I have tweaked your previous threads. Thanks!
On my 99 42, The water heater is located on the Bulkhead Behind the Port Motor. Drains towards the gunnel. Its a stainless steel contraption.