As the "Collector" ages, the definition of what an "Old Outboard" is changes. At meets now, you will see more of what are defined as "Classic Motors" (and Boats). Below is a video that shows examples of this progression in collecting. Reference the "What is an Antique Outboard" article below.
There may be some confusion about what exactly is an “antique outboard”. Any old outboard motor is not necessarily an antique.

From AOMCI official By Laws:

Section 2. Categories:
(a) Antique: Outboard motors manufactured in 1950 or before shall be recognized as antique.
(b) Classic: Outboard motors manufactured after 1950 and which are at least thirty (30) years old in this current year (real time) shall be recognized as classic.”

AOMCI rules state that 1950 is the cutoff for calling an outboard motor an Antique. This is not a moving date.
From 1950 to 30 years prior to this current year is a Classic. Therefore in 2012 anything before and including 1982 is a Classic. This is a moving date and changes every year.

Using these rules, here are some examples.
A 1906 Waterman is an Antique.
A 1950 Evinrude is also an Antique.
A 1951 Evinrude is a Classic but not an Antique.
A 1982 Mercury is also a Classic.
A 1983 Merc is just an old outboard; however next year it will become a Classic.
AOMCI Local Chapters have specific qualifications for judging and events:

Several chapters have judging for “rowboat motors”. A simplified explanation would be if it has a knob on top of the flywheel this would be a
row boat motor and usually cast iron cylinders.

However, there are little gray areas. Two examples are:
The Elto Ruddertwin first made in 1922 has a starter knob start but is made of aluminum.
A Koban with a steering wheel type flywheel has no knuckle buster knob but is also considered a rowboat motor.

To make events interesting these contests:
Some examples of wet events and barrel events are:
How slow can you go? (rpms in barrel with tachometer)
Stock Zephyr races (12 foot unmodified retail boat)
Modified Zephyr Races (zephyr powerhead, any boat)
6HP and 3HP races.
Cup of gas contest. (how long can it run in a barrel?)
Timed event

So if at events you are not showing your outboards or running them in events you are missing most of the fun !

Is it an Antique?
Observation by Don Saulsbury - "Collector"