WASHINGTON — The Coast Guard recommended Wednesday that operators of small boats raise weight estimates for passengers to reflect that Americans have gotten fatter since the first rules in 1942.

Small boat operators should consider people are 185 pounds, instead of the old size of 140. The recommendation arises from an investigation of an accident in which an overloaded water taxi capsized and killed five people in Baltimore in 2004.

The operator assumed that the average passenger weighed 140 pounds, based on the Coast Guard's standards for a mix of men, women and children in calm inland waters. For passengers in boats on the ocean, the standard was 160 pounds.

The Centers for Disease Control and Prevention estimates that the average American gained more than 24 pounds between the 1960s and 2002, for a weight of 177.7 pounds without clothing.

The Coast Guard settled on a single standard of 185 pounds and made it voluntary until new rules are established, spokeswoman Angela McArdle said. "We wanted to provide guidance before the season starts."

Too much passenger weight was an issue in several other deadly accidents, including the 2003 crash of a small plane in Charlotte, N.C., in which 21 people were killed on takeoff, and the sinking of the Ethan Allen tour boat on Lake George in New York last fall, which killed 20 older people, 19 of them from Michigan.

Coast Guard Revises Weights