Note:  This is the start of a page devoted to the use of private yachts during World War II.  Please consider it a work in progress, and forward any relevant information you may have so that we can include it here.

The May 1942 issue of Pacific Motor Boat magazine had a cover story on the Coast Guard Auxiliary, which is scanned and attached below. On the Editor's page the article was introduced as follows:

The growing hundreds of Pacific Coast boat owners enrolled as members of the Coast Guard Auxiliary receive special recognition in this issue of Pacific Motor Boat.

The Auxiliary is not to be confused with the Coast Guard Reserve. In the Reserve, boats are loaned out-right for the duration, to be maintained and operated by the Coast Guard itself. The owner may or may not choose to enter service; if he does, he becomes a member of the armed forces as an enlisted man, rating or commissioned officer of the Coast Guard Reserve.

In contrast, Auxiliary enrollment involves only the part-time services of members and their boats on a purely voluntary, unpaid basis. They receive no compensation for the use of their craft, nor for their own time. Assignments are rotated, with each member called upon in turn to handle his share of a flotilla's duties.

Highly significant are two facts about Auxiliary activity; first, the routine harbor patrols, picket duty, and special services they perform serve to release many a regular Coast Guard boat for other urgent purposes, and second, the Auxiliary fleet of well-found small craft in the hands of trained skippers is a mighty valuable kind of reserve force in any emergency.

Excerpt from The United States Coast Guard in World War II: A History of Domestic and ... By Thomas P. Ostrom:

The Coast Guard utilized several kinds of watercraft and crews to complete the prewar and wartime missions assigned to the service. It acquired private pleasure craft to patrol harbor areas. Coast Guard reservists ran hundreds of these craft, with "CGR" and a designated number stenciled on the bow. The  CGR numbers, unlike CG boat numbers, did not indicate the length of the boat.  The Coast Guard usually designated a name on craft more than 100 feet in length and put a number on the hull of craft less than 100 feet.  Most of the watercraft were returned to the owners after the war.

Private yachts and fishing boats were gradually armed by the Navy with depth chanrges, machine guns, and sound (sonar) gear. Patriotic yacht owners, many with Reserve officer commissions, manned their vulnerable vessels far out to sea in often stormy waters at significant cost and risk.  The fledgling crews stood by to report submarine activity and initiate rescue missions.

External Links:

War Regulations in Puget Sound (March 1942):

Puget Sound War Regulations - Pacific Motor Boat Magazine, March 1942
from Pacific Motor Boat Magazine, March 1942