Boat Weight Regulations

The average American has put on a considerable number of pounds in the past 40 years, so many that the U.S. Coast Guard recently adjusted the federal safety regulations governing the number of passengers that may be carried aboard commercial vessels, such as tour boats, water taxis, and ferries, meaning they're allowed to carry fewer people than before. The Coast Guard is concerned about what might happen if heavy passengers all move to one side, for example, when a ferry docks or an excursion boat moves in to view a migrating pod of whales. Will federal weight capacity regulations for recreational vessels change as well?

"We don't see a need to follow this line of action for recreational boats at this time," said Phil Cappel, chief of the Coast Guard's Recreational Boating Product Assurance Branch. He explained that the "recreational boat persons" capacity equation is based on a family of four — with an average weight per occupant of 165 pounds, and takes into account the variety of different boat types and hull configurations.

"As with all of our safety regulations, they're reactive and not proactive," Cappel explained, "which means we need to have proof that heavier boaters are increasing the number of accidents, injuries, or deaths before we can move forward with regulatory action. We have not seen any proof to that effect in our accident data."

Recreational monohull boats up to 20 feet in length are required to have capacity labels indicating what's safe to carry in terms of engine horsepower, cargo (including gear and engines), and passengers. Hull displacement — the mass of water a hull displaces when floating — is the basis for all weight capacity calculations. "Persons" capacity information includes both the number of passengers who may be carried safely, as well as the total weight of those passengers. It's the most prominent information listed on the capacity label, because people are considered to be the "live load," meaning they can move around inside the boat, affecting stability. Overloading a boat reduces freeboard and increases instability and the risk of swamping in rough weather.

Vessels of more than 20 feet aren't required to have labels, although boats up to 26 feet built to the American Boat & Yacht Council (ABYC) standards adopted by the National Marine Manufacturers Association (NMMA) do. An estimated 94 percent of recreational boats sold in the U.S. are built by 145 companies, all of which are members of NMMA and are required to follow the organization's boat and yacht certification guidelines.

The weight capacity ratings for commercial passenger vessels, which are governed by a completely separate set of federal regulations than for recreational boats, were adjusted in response to a report by the Centers for Disease Control and Prevention (CDC) showing that the average weight of an individual in the United States has increased to 185 pounds, up significantly since the passenger-carrying regulations went into effect in the 1960s, when the average American weighed 160 pounds.

"We realize that there is not always a family of four aboard a recreational boat and that the average weight of Americans has increased," Cappel said. "Recreational boats have a safety factor built into the capacity calculations and can carry much more weight than the maximum weight placed on the capacity label."

According to John Adey, ABYC's technical director and one of the BoatUS Ask The Experts, recreational outboard-powered boats can safely carry a pound of weight — in passengers, cargo, or engine — per five pounds of displacement. On inboard- and stern drive-powered boats, this "fudge factor" ratio goes to one pound of weight to seven pounds of displacement. He added that safe passenger loading is also controlled by the number of "underway seating positions." For example, two slim adults taking four or five small children out for a spin on a boat designed to seat four would be taking a big safety risk, even though the total passenger weight might be well under the boat's stated capacity.

Adey said that ABYC paid close attention when the Coast Guard announced changes to the commercial-vessel passenger-carrying regulations. "Everyone had the perception that [the criteria for determining] recreational boat capacities were about the same as those for commercial vessels." But, he said, the cargo-weight-to-displacement "fudge factor" makes loading recreational boats a bit safer.

Federal weight capacity ratings are not mandatory and are intended as a guide for boat operators. Even so, state boating law-enforcement agencies may hold operators accountable for overloading or unsafe loading.

Float Your Boat

Federal requirements mandate that outboard-powered boats 20 feet and under must be built with enough flotation to keep the passenger-carrying area at or just below the water's surface, in the event of swamping or capsizing. Inboard- and I/O-powered boats' designs warrant less rigorous basic flotation requirements, which allow that one part of the hull remain above the surface of the water. In both cases, a "survival platform" is created where boat occupants can stay until help arrives. If an overloaded boat swamps or capsizes, its built-in flotation may not be sufficient to keep the hull from sinking.

Sailboats, regardless of size, are not subject to flotation requirements — not because they don't sink, but simply because, by Coast Guard calculations, they're not involved in enough accidents to warrant tougher standards.

Weight, Weight — There's More!

Matching the correct horsepower engine to the boat is also an essential consideration that involves weight and safe loading. In addition to persons-weight capacity, boat labels must indicate the maximum horsepower the boat can safely handle. Horsepower capacity deals with two concerns that must be addressed when attempting to match an outboard engine to a boat: horsepower and weight. Too much power can make a boat difficult to control and too much weight, whether "live load" or gear, can lead to stability problems.

Federal horsepower ratings apply only to outboard engine-powered boats less than 20 feet in length. When these regulations were written in the early 1970s, virtually all outboards suitable for smaller boats were two-stroke configurations covering a broad range of horsepower. In the past decade, however, four-stroke outboard engines have broken higher and higher horsepower thresholds, making them viable candidates for installation on more boats. But, due to more complex valve systems, four-stroke engines weigh 10 to 15 percent more than their two-stroke counterparts.

Do boats equipped from the factory with four-stroke engines create a handling and stability risk? Are boaters who retrofit their vessels with four-stroke engines taking a dangerous chance? No, according to John Adey. Once again, the fudge factor that provides a margin of safety when loading passengers gives boat operators some leeway with engines. Plus, ABYC's engine-weight calculations are updated annually to reflect new models and new technology. Will federal standards be rewritten to include four-strokes? "Probably not," Adey says. "Once you achieve a high level of safety, there's no point in backing off.