You need 6 months actual sea service as engine room crew, the other 30 months can be made up of any of the items listed in the table of section 147 of the Marine Personnel Regulations.
http://laws-lois.justice.gc.ca/eng/regu ... .html#h-42
vis:
Either having successfully completed a 3-year approved cadet training program in marine engineering or having acquired at least 36 months of qualifying service comprising the following:
(a) at least 6 months as an engineer, engine-room rating or assistant engineer, performing the duties set out in subsection (2) in an engine room on one or more of the following vessels the main engines of which have a total power of at least 500 kW:
(i) a motor vessel, in the case of an applicant for a motor ship certificate, or
(ii) a steamship, in the case of an applicant for a steamship certificate;
(b) a credit of 6 months of qualifying service if the applicant submits the certificate referred to in subparagraph 3(f)(i); and
(c) any remaining time in any combination of the following types of service:
(i) up to 12 months of fitting, erecting or repairing machinery,
(ii) up to 6 months of metal turning,
(iii) up to 6 months of brass finishing,
(iv) up to 6 months of planing, slotting, shaping and milling,
(v) up to 3 months of welding,
(vi) up to 6 months in a drafting office as mechanical or electrical drafter engaged in arrangement, detail or design drawings,
(vii) up to 24 months as an engineer or assistant engineer on day work,
(viii) up to 6 months as an engineer, engine-room rating, assistant engineer or electrician during the fitting out, laying up or refitting of one or more vessels,
(ix) up to 24 months as the person responsible for operating pumps on one or more tankers,
(x) up to 24 months as an engine-room rating or assistant engineer performing watchkeeping duties in an engine room on board one or more towed barges or similar vessels, the boiler or boilers of which have a total heating surface of at least 92.9 m2,
(xi) up to 9 months as person responsible for operating tunnel machinery on one or more self-unloading bulk cargo ships,
(xii) up to 24 months as an electrician on one or more vessels that have a rated generator capacity of at least 300 kW,
(xiii) a credit of 12 months of service for successful completion of an approved training program in diesel engines,
(xiv) a credit of up to 3 months of service for each of the following courses that has been successfully completed, at an institution recognized by a provincial government or foreign administration:
(A) applied mechanics,
(B) thermodynamics,
(C) machine design,
(D) electrotechnology, and
(E) naval architecture, and
(xv) a credit of 12 months of service for successful completion, at an institution recognized by a provincial government or foreign administration, of a training program in mechanical or electrical engineering.
So, 12 months in a training programme in mechanical or electrical engineering, 12 months fitting, repairing or erecting machinery and 2 more months doing something in that table and you're off to the races. You need basic skills training for 4th Class STCW III/1 anyway, that's your training programme. Chances are you've done trade training in Oz which could be acceptable if it was a mechanical or electrical trade. Chances are you've worked on mechanical or electrical machinery, too. All you need is a testimonial saying so.