You might not find a manual anyplace.

Most boats are sold with a collection of manuals, one for each major
system. People expect an "owners manual" like they'd find in a Ford or
a Buick (and maybe they should) but there are few ever printed in the
traditional sense.

One of the challenges is that a builder might switch suppliers for a
major component halfway through a production year.....or, maybe buy
systems from 2-3 suppliers simultaneously. Instructions "To start cabin
heater" for example, would be a little bit different with an Espar vs.
a Webasto.