Dave Gerr - Boat Mechanical Systems Handbook-How to Design, Install, and Recognize Proper Systems in Boats

Worked out in English units:

Step 1. Draw the half-areas of the front,

middle, and back of the tank.

Taking the preceding measurements, we

draw the three shapes (Figure 6-3).

Step 2. Calculate the area of each of the

three shapes.

In this case, you divide each section into a

regular trapezoid and a triangle. Using the

formulas for plane areas (Appendix A),

find the area of each and add to get the

total area of each section (end, middle,

and front).

Step 3.Use the prismoidal formula to find

the volume and the preceding tables to

find the capacity in gallons. (Don’t forget

to multiply by 2 to get total area, since

you used the half-areas of the tank.)

2.6 cu. ft.× 7.48 gal./cu. ft.× 2 sides =38.9 gal.

Always deduct 2% for internal framing,

baffles, and small air pockets:

38.9 gal. ×0.02 =0.78 gal.

38.9 gal. – 0.78 gal. =38.12 gal.

This is a 38-gallon tank.

Or

Worked out in metric units:

Step 1. Draw the half-areas of the front,

middle, and back of the tank.

Taking the preceding measurements, we

draw the three shapes (Figure. 6-4):

Step 2. Calculate the area of each of the

three shapes.

In this case, you divide each section into a

regular trapezoid and a triangle. Using

the formulas for plane areas (Appendix A),

find the area of each and add to get the

total area of each section (end, middle,

and front).

Step 3.Use the prismoidal formula to

find the volume and the preceding

tables to find the capacity in liters.

(Don’t forget to multiply by 2 to get

total area, since you used the half-

areas of the tank.)

0.074 m^3 × 1,000 L/m^3 × 2 sides =148 L

V (one-half tank)

0.055 m^22 (4 0.087 m )

=

+× +00.123 m

6

0.838 m 0.073 m

2

3

⎛

⎝

⎜

⎜

⎞

⎠

⎟

⎟

×

=

PART TWO:FUEL SYSTEMS

Figure 6-3. Tank
half-sections (in
English units)

V (one-half of tank)

0.59 sq. ft. (4 0.

=

+×994 sq. ft.) 1.33 sq. ft.

6

2.75 ft.

+

×=

⎛

⎝⎜

⎞

⎠⎟

2.6 cu. ft.