All I know is that his boat papers show Aussie registration; the flag
he flies is Aussie and the word "Hobart" is carved in teak beneath the
boat's name "Kulkuri", also carved in teak.

It may be that, like mine, it has expired.

No. Australian shipping registration for pleasure craft, as it stands
at the moment, does not expire (unlike NZ or US documentation). Each
of the separate states and territories has its own registration, which
involves re-registering the vessel annually, but Australian shipping
registration does not require annual or 5-annual renewal.

In Malaysia, we do not even ask for boat papers. All that is required
is to have your passport stamped. The fact that you arrived by yacht
doesn't really matter - so far as Customs etc is concerned, you could
have swimmed. The Harbour Master's (with Jabatan Laut) dept is not
interested in yachts either. They are more interested in big shipping
and the Indonesian barter trade boats.

Hmm ... every time I've entered and exited Malaysian waters I've had
to fill out forms for Jabatan Laut that require entry of the vessel's
official number etc. Jabatan Laut officers often do not ask to see the
papers, but they want their forms filled in and submitted. In
Malaysia, port clearance is handled by Customs (clearing in and out
with Jabatan Laut, the Marine Department, is more for JL's sense of
control than anything else) and Customs generally do want to see the
original copy of the ship's papers.