Section NR 5.12 - Specifications for determination of horsepower and weight capacity and recommended number of persons(1) DETERMINATION OF WEIGHT CAPACITY OF THOSE VESSELS COVERED BY S. 30.501, STATS., DESIGNED FOR OR REPRESENTED BY THE MANUFACTURER AS BEING SUITABLE FOR USE WITH OUTBOARD MOTOR OR DESIGNED TO BE PROPELLED BY OARS, EXCEPT THOSE VESSELS DEPENDENT SOLELY UPON THE BUOYANCY OF PONTOONS OR SIMILAR FLOTATION DEVICES. (a)Step 1. The cubic volume of the hull shall be determined up to a reference plane (static float line) which passes through the lowest point of major leakage, such as the low point of the gunwale, transom cut-out or top of motor well, and is parallel with a line connecting the intersections of the sheer with the forward face of the stem and the sheer with the after-face of the transom. "Sheer" is defined as the intersection of the hull with deck, gunwale or super-structure.(b)Step 2. The weight capacity shall be determined by converting the hull cubic volume (Step 1) to the weight of water displaced by this volume as follows: multiply the product of Step 1 by 62.5, then subtract the weight of the vessel, and divide the remainder by a safety factor of 5.(c)Work sheet. The following work sheet (Table I) can be used in determining the weight capacity of the hull. The figures to be inserted are taken from the boat dimension drawings (Table II) to which the letters under the blank spaces refer. All dimensions should be converted to decimal numbers before insertion in the formula. Table III converts inches and eighths of inches to the decimal equivalents in feet.(2) DETERMINATION OF WEIGHT CAPACITY OF THOSE VESSELS COVERED BY S. 30.501, STATS., WHICH HAVE PERMANENTLY INSTALLED ENGINES, EXCEPT THOSE VESSELS DEPENDENT SOLELY UPON THE BUOYANCY OF PONTOONS OR SIMILAR FLOTATION DEVICES. (a) Weight capacity shall be determined in the same manner as for vessels represented as being suitable for use with outboard motor except that the weight of all machinery and associated operating gear including battery, fuel and fuel system shall be subtracted.(3) DETERMINATION OF WEIGHT CAPACITY OF THOSE VESSELS COVERED BY S. 30.501, STATS., WHICH ARE DEPENDENT SOLELY UPON THE BUOYANCY OF PONTOONS OR SIMILAR FLOTATION DEVICES. (a) Weight capacity shall be determined by the following tests or by the substitute method provided if the conditions stated therein are met. The tests shall be conducted with the maximum horsepower motor for which the boat is recommended and with full fuel tanks and operating equipment in normal position. 1. The transverse stability shall be tested by adding weight on the lower deck in the extreme outboard position which the arrangement permits (i.e., within one foot of the edge) until the top of the pontoon on the loaded side becomes awash.2. The longitudinal stability shall be tested by adding weight on the lower deck evenly about a point 1/4 of the length of the deck from forward until the edge of the lower deck becomes immersed. This test shall be repeated at the after end of the craft by adding weight evenly about a point 1/4 of the length of the deck from aft until the edge of the lower deck or the top of the motor mounting bracket becomes immersed, whichever occurs first.3. In a design having more than one deck intended to support passengers (i.e., having railings and means of access), the tests in subds. 1. and 2. shall also be conducted by adding weight in the specified locations on the upper deck until the conditions specified in subds. 1. and 2. respectively are attained. 4. Ninety percent of the least of the weights attained by the tests in subds. 1. and 2. shall be the weight for passengers. TABLE 1 - CAPACITY FORMULA WORK SHEET
Step 1.
Compute Areas of Sections
Note: For maximum allowable height (H) in any section, check inside this form.
Compute Cubic Capacity
Formula:
Step 2.
Compute Maximum Weight Capacity
Note: The volume of integral structure aft of the transom below the static float line may be added to the calculated cubic capacity.
TABLE III
Inches To Decimal Feet
Inches | Decimals |
1/8" | .010' |
1/4" | .021' |
3/8" | .031' |
1/2" | .042' |
5/8" | .052' |
3/4" | .062' |
7/8" | .073' |
1" | .083' |
2" | .167' |
3" | .250' |
4" | .333' |
5" | .417' |
6" | .500' |
7" | .583' |
8" | .667' |
9" | .750' |
10" | .833' |
11" | .917' |
DEPARTMENT OF NATURAL RESOURCES
5. The weight capacity for the craft shall then be the sum of the weight for passengers plus the weight for the maximum horsepower motor for which the boat is recommended, full fuel tanks and operating equipment. (b) A substitute method for determining the weight capacity of pontoon boats may be applied to pontoon boats having only one deck. The deck must be within the width of the pontoons, must be no more than 6 inches above the pontoons, its length within the railings must be no more than 80% of the pontoon length, must not overhang the pontoon, and must be capable of draining overboard freely. If the boat complies with these conditions, the weight capacity shall not exceed one half of the reserve buoyancy of the boat which shall be determined by subtracting the weight of the vessel including the weight of the maximum horsepower motor for which the boat is recommended, full fuel tanks and normal operating equipment from the buoyant force of the boat's pontoons or similar flotation devices. (4) PASSENGER CAPACITY. The recommended passenger capacity of those vessels covered by s. 30.501, Stats., shall be determined by the following equations, using whichever is less: (5) LINEAR MEASUREMENTS. In the preceding paragraphs of this section all linear measurements are taken outside planking or plating and recorded in feet with decimal equivalents for inches and eighths, all volume measurements in cubic feet and all weight measurements are in pounds.(6) MAXIMUM SAFE HORSEPOWER CAPACITY. The determination of maximum safe horsepower capacity of outboard equipped motorboats less than 20 feet in length covered by s. 30.501, Stats., shall be calculated by the use of the following formulas: (a)Step 1. Measure length of vessel (midline measurement) and the width of the transom (or back of the boat) (across the top), recording in feet and inches. Convert inches to hundredths of a foot (Table 1). Multiply length times width to determine FACTOR. For .5 or above round off FACTOR to the next higher whole number. If FACTOR number is between 0 and 52, use Table 2 to determine maximum safe horsepower capacity in calm water. Table 1
Inches | Hundredths | Inches | Hundredths |
1 | = 0.08 | 7 | = 0.58 |
2 | = 0.16 | 8 | = 0.66 |
3 | = 0.25 | 9 | = 0.75 |
4 | = 0.33 | 10 | = 0.83 |
5 | = 0.41 | 11 | = 0.91 |
6 | = 0.50 | 12 | = 1.00 |
Table 2
If your factor number is between 0 and 52, your safe outboard horsepower capacity is as shown below: |
If factor is between | safe horsepower capacity is: |
0 - 35 | 3 |
36 - 39 | 5 |
40 - 42 | 7.5 |
43 - 45 | 10 |
46 - 52 | 15 |
(b)Step 2. If FACTOR number is larger than 52.0, the safe outboard horsepower capacity is figured according to the type of steering and the height of the transom. Measure transom height in inches (measure from bottom of keel to lowest point of the transom). For outboards with remote steering and a transom height of at least 20 inches, multiply the FACTOR by 2, subtract 90 and raise the answer to nearest multiple of 5. The resulting number is the maximum safe horsepower in calm water. Note: Following are examples of how to raise answer to nearest multiple of 5:
If the second numeral in your answer is a 5 or a 0, DO NOT CHANGE ANSWER.
If the second numeral in your answer is 1, 2, 3, or 4, change it to 5. For example, 21, 22, 23, or 24 would all be changed to 25.
If the second numeral in your answer is 6, 7, 8, or 9, change it to a 0 and raise the first numeral by 1. For example, 26, 27, 28, or 29 would all be changed to 30.
(c)Step 3. For outboards that do not have remote steering or the transom height is less than 20 inches, multiply FACTOR by 0.8, subtract 25 and raise the answer to nearest multiple of 5. The final answer is the maximum safe horsepower in calm water.(d)Step 4. For flat-bottomed, hard chine (where the side meets the bottom) outboards that do not have remote steering or the transom height is less than 20 inches, multiply FACTOR by 0.5 and subtract 15, raise answer to the nearest multiple of 5, the final answer is the maximum safe horsepower in calm water.Wis. Admin. Code Department of Natural Resources NR 5.12
Cr. Register, March, 1966, No. 123, eff. 4-1-66; renum. from WCD 5.12 to be NR 5.12, Register, March, 1971, No. 183, eff. 4-1-71; cr. (6), Register, April, 1985, No. 352, eff. 5-1-85; am. (6) (intro.), Register, July, 1993, No. 451, eff. 8-1-93; am. (6) (b), Register, May, 1995, No. 473, eff. 6-1-95.The above formulas and tables used to determine maximum safe horsepower capacity for outboard motorboats appear in 33 CFR 183.53.