A few basic terms are in order: Whatever a flag's shape, its vertical dimension is its hoist, and its horizontal extent is its fly. The main part of the flag is called either the field or ground; the upper left quarter of the flag is known as the canton or the union.

There are several types of flags that concern the yachtsman. First and most important are the national colors, often called the ensign. We commonly refer to the nation's flag in the plural, but when one talks about "making colors," the phrase normally includes several flags, one of them the national ensign.

Next most common aboard yachts is the burgee, a usually triangular flag that denotes membership in a yacht club or other local boating organization.

In the U.S., an owner's individual flag is called a private signal, while in Britain it is sometimes referred to as a house flag. In either case, it is most often a swallowtail shape, although triangles and rectangles are not uncommon.

Related to the private signal is the organizational officer's flag - yacht club commodore, Coast Guard Aux. Flotilla Commander, etc. Incompatible combinations are officers' flags from one club displayed with burgees from another or two burgees raised at once.

Seldom seen aboard yachts, the Union Jack is a national flag that derives from naval usage. In the U.S. it is the 50 star union of the national flag, displayed only at a vessel's bow or jack staff, only at anchor or tied up, and only on Sundays or holidays.

There are also numerous signal flags serving more or less useful purposes, from the oversize Race Committee banners seen at regattas to the International Code flags to the various gag flags suggesting the presence of booze, lust or terminal bad taste aboard the vessel hoisting them.

Single masted sailboats normally have three possible locations from which to display flags - the masthead, the starboard spreader and aft (the mainsail leech or the stern staff). Underway under sail alone, the traditional recipe has been that the burgee appears at the masthead and the ensign at the gaff or two-thirds the way up the leech of the main. An organizational flag, a courtesy flag when in foreign waters or a signal may appear at the spreader hoist.

The ensign has migrated from the mainsail leech to the stern staff, a move formally recognized in the early '70s by both the New York YC and the USYRU. Purists resisted the change, but it seems safe to say that a vast majority of Bermudian sloops now carry their ensigns at the stern under sail or power.

Another change that's taking place - albeit unrecognized by any authority - but now apparently standard, is the descent of the burgee from the masthead to the starboard spreader. Now that most mastheads have become electronics forests, it has become not only difficult but potentially expensive to plant a flag among all the delicate feelers.

When a single masted sailing yacht is underway under power, or a combination of power and sail, former usage called for the ensign to be removed from gaff or leech and reappear on the stern staff. Now, the ensign is normally flown from the stern staff.

At anchor, under normal circumstances, the flag conformation is the same as under power. On festive occasions the boat may also be dressed overall with the flags and pennants of the International Code.

The flag usage aboard yawls is essentially the same as aboard single-masted sailing yachts, except that the mizzen offers a third possible location for the ensign, as it can be carried on the leech (normally about 2/3 up the leech).

Although today's tendency seems to be to hoist as many flags as one can possibly fit on the boat, each of them is likely to be too small for the purpose. Barring absurd extremes, however, a large flag generally looks better than a small one, and the rule of thumb for size ought really to be considered a minimum.

That rule calls for the ensign to be one inch on the fly for each foot of boat length overall. The burgee, house flag and officer's flag are half an inch on the fly for each foot above water of the highest truck, for sailing yachts and auxiliaries. The courtesy flag used in foreign waters is normally half the size of the yachts own ensign, but flags intended as meaningful signals - Code signals, etc. - should be as large as can conveniently carried.

The basic rule is that colors are made at 0800 local time and at sunset. Flags may be displayed before or after the hours for colors when entering or leaving port.

When a yacht visits foreign waters, custom calls for her to hoist the courtesy flag. Many countries have more than one national flag, and the proper courtesy flag is a half-sized version of the nation's yacht or merchant vessel ensign. In Canada, the national flag is flown on ships and yachts and also by visitors. As a matter of politeness, the courtesy flag occupies a place in the hierarchy second only to the vessel's own national ensign, but it is primarily a signal, and thus takes the position normally reserved for that sort of flag. On sailing or masted power yachts, this is usually at the forward starboard spreader. The foreign-going yachtsman is well advised to keep an eye on what other visiting yachts are doing, and follow their example.

On festive occasions a vessel fully dressed in flags and pennants of the International Code adds a colorful touch to any harbor.

A yacht dressed overall wears the flags she would normally hoist under the circumstances, as well as the 39 code flags. Since there are 26 square alphabet, three triangular repeater pennants and 10 truncated pennants representing numerals, normal procedure calls for alternating two letters with every number or repeater. There is no absolute arrangement. The arrangement is supposed to run in an unbroken arch from waterline to waterline, which means that two flags will almost touch the water.

In summary, on a larger sailing yacht, there are five or sometimes six places from which flags may be flown: a) the stern staff (national ensign under power or under sail); b) the leech of the aftermost sail (national ensign under sail); c) main or foremast truck (yacht club burgee, or, in the case of a single masted vessel, the owner's private signal or officer's flag); d) mizzen truck (owner's private signal or flag officer's flag); e) forward starboard spreader (organizational flag other than burgee, courtesy flag when in foreign waters); and f) the bow or jack staff (Union Jack at anchor on Sundays or holidays).

Further reading:

How to fly flags, Canadian Power & Sail Squadron

Flags, Nautical Know How