For pond fabric sizing, the length is calculated using maximum length multiplied by which expression?

• A. Depth plus three feet
• B. Twice the depth plus three feet
• C. Three times the depth
• D. Twice the depth

Answer: (B)

Sizing pond fabric is about allowing enough material to wrap up the sides and have a margin for securing and overlaps. The depth of the pond tells you how far up the sides you need the fabric to extend on each end, so you need material for both ends, which is why you multiply the depth by two. The extra three feet gives a safe margin for overlapping and anchoring at the top edge. Therefore, the length of fabric is the maximum length times (2 × depth + 3 ft). For example, with a maximum length of 20 ft and a depth of 4 ft, you’d need 20 × (2×4 + 3) = 20 × 11 = 220 ft of fabric. The other options either omit the double-depth allowance or the additional margin, so they don’t provide enough (or too much) scrap for proper fitting.