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PEOPLE AND POUNDS

Why do the regulations require the display of the maximum

persons capacity in the number of people and the number

of pounds?

Label effectiveness studies reveal that persons capacity in

whole numbers of persons is a more effective means of

communication than persons capacity in pounds and that

people can better identify and comprehend information pre-

sented in that way. Accordingly, the U.S. Coast Guard Maxi-

mum Capacities label format highlights persons capacity as

a whole number of persons.

The Coast Guard considered several methods of calculating

persons capacity as a whole number. Methods used by inter-

national boating safety organizations, state boating safety

programs and various voluntary standards were examined.

Several major factors were considered important in deter-

mining an appropriate formula for computing persons ca-

pacity as a whole number. One is the assumed weight of the

average person, which when divided into the persons capac-

ity in pounds, results in the number of persons that may be

carried. The weight of the average person as used in indus-

try standards, State laws and international standards

ranged from 150 to 165. Studies of boating accidents indi-

cated average weights of 162 and 157 pounds. The Coast

Guard adopted 160 pounds as the weight of an average

person. [This was changed to 185 pounds in 2011.]

Another major factor was the grouping of persons in the

typical boating outing, which is usually a combination of

adults and children indicating that some adjustment in the

number of persons that may be carried was necessary. The

typical group on a boating outing was three to four perso

as indicated in surveys conducted by the Coast Guard. Thi

group was typically a boating family of two adults and on

or two children.

A third major factor was the different types of boats to

which the formula would apply. Because of the variations

boat sizes and resulting loading capacities it was imperat

that the formula apply equally to all boats without unduly

restricting the usage of some boats and without allowing

excessive capacities for other boats which could be hazar

ous.

An analysis of boats and their respective maximum perso

capacities was conducted taking into consideration the f

tors discussed above. The result was a straight-line graph

which converted a boat's persons capacity in pounds to a

persons capacity in whole numbers of persons. In order t

avoid errors of interpolation, the graph was reduced to a

simplified mathematical formula, which involves adding

pounds to the persons capacity in pounds, dividing the re

by 141 and rounding off the answer to the nearest whole

number. [The number “141” does not specifically represe

a single person’s weight. The “141” is a constant in the

mathematical formula generated from the straight-line

graph.]

Under the formula adopted, a boat that has a maximum

persons capacity of 500 pounds has a whole number per-

sons capacity of four. Some existing State laws required

dividing the 500 pounds by the average weight of a perso

and displaying a fraction of a person on the capacity labe

In this example, using 160 pounds for a person, the resul

was approximately 3.12 persons. This

Understanding ABYC H-5

Boat Load Capacity

,

Persons Capacity and the Mysterious Number 14

In ABYC H-5

, section 5.6 presents a formula stating:

One of the most common questions we get at the Tech Department is, "Isn't 141 pounds too little weight for modern

American boaters?" In fact, the number 141 is not a weight. It's a constant from the capacity formula developed by the

U.S. Coast Guard. The following excerpt from U.S. Coast Guard “Boating Safety Circular 68,” from March 1989, will expl

the persons capacity formula.

John Adey, ABYC Vice President & Tech Dept. Dire

U.S. Coast Guard

Boating Safety Circular 68

- March 1989

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