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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
Boat Load Capacity
, section 5.6 presents a formula stating:
The persons capacity shall not exceed the value determined by dividing the quantity of 32, plus the posted persons
pound capacity, by 141 and rounding up or down to the nearest whole number.
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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