The Flag Advisor - 1
From Active Cap't:
Nearly every cruising boat on the water flies one or more flags. But get
into a discussion about flag etiquette and rules, and no one can seem to
agree on the full set of what's right and what's wrong.
So we'll take it on over the summer. We'll research the generally
accepted practices and bring a couple of topics into the discussion.
Note that we're going to present the findings for recreational boats.
Military, government, or special use boats might well have different
sets of rules and accepted practices.
For this first part, we'll discuss the rules surrounding national and
courtesy flags, and flag sizes.
Courtesy and national flags
Rule 1. There are no real rules. There are customs and some flag
etiquette rules that have been adapted for boats. However, when visiting
another country, make sure there are no laws about flying courtesy flags
because boaters have been known to receive fines. It is often an insult
to fly a courtesy flag of another country incorrectly.
2. A vessel's national flag is flown from the stern.
3. If not prohibited, you can fly another location flag (state, province,
territory) at the main masthead in place of any private, yacht club, or
officer's flag. On a mastless boat, a state flag flies from either the bow
or radio antenna.
4. Only the national flag should be at the stern. It is considered a
place of honor for the vessel's national flag. Never put any other flag
there.
5. Do not fly a courtesy flag (a small flag of the country you're
visiting) until your vessel has been properly cleared by customs and
immigration. Until clearance is complete, fly the yellow Q (quarantine)
flag.
6. On a powerboat without a mast, the courtesy flag replaces any flag
that is normally flown at the bow.
7. On a powerboat with a mast and spreaders, the courtesy flag is flown
at the starboard spreader. On a powerboat with two-masts, the courtesy
flag is flown from the starboard spreader of the forward mast.
8. On a sailboat, the courtesy flag is flown at the starboard spreader.
On sailboats with more than one mast, the courtesy flag is flown from
the starboard spreader of the forward mast.
9. Don't fly a foreign courtesy flag after you return to your home
country.
Flag sizing
These are not well agreed upon. Chapman's suggests the following:
1. The national flag at the stern of your boat should be one inch long
for every foot of overall vessel length rounded up to a normally
available size.
2. Other flags (club burgees, private signals, courtesy flags) should
be one-half inch long for every foot of overall vessel length.
Another competing sizing suggests:
1. Boats up to 50 feet in length should use a 16 x 24 inch national
flag and 12 x 18 inch courtesy flags.
2. For every 25 additional feet in length, increase the size by one
standard size.
Flags give your boat some identity and even add some beauty. We'll
continue with some of the other accepted rules in future segments.
Or I'll add a third, dedicated to the flag. 
