2006 Moomba Outback V - Stock heater and wiring

We've had our boat for several years and if you can believe it in this Canadian weather :-) we've never used the heater. We have the manual which indicates that we have the heater in our model but there is no actual heater switch anywhere (as shown in the manual) yet we have the heater snorkel tubes etc. We want to attempt to trace the wiring so we can hook it up to one of the auxillary switches. Anyone out there have any schematics on the wiring or can help us in any way?

Thanks!