Question

Arrange the otter boards in decreasing order of their aspect ratio
A. Rectangular flat otter board
B. Rectangular V otter board
C. Oval profile otter board
D. Suberkrub otter board
Choose the correct answer from the options given below

• A. A, C, D, B
• B. D, B, C, A
• C. C, A, D, B
• D. B, C, D, A

Hint:

High aspect ratio boards (like Suberkrub) are more efficient as they produce more lift with less drag, but they are less stable on the seabed. Flat, low aspect ratio boards are the most stable for bottom trawling.

Answer 1

The Correct Option is B

Step 1: Understanding the Question:
The question asks to rank different types of otter boards (used in trawling to keep the net open) based on their aspect ratio in a decreasing order.
Key Formula or Approach:
The Aspect Ratio (AR) of an otter board is defined as the ratio of its height (vertical dimension) to its length (horizontal dimension):
\[ \text{Aspect Ratio} = \frac{\text{Height}}{\text{Length}} \]

Step 2: Detailed Explanation:

• Suberkrub Otter Board (D): These are high-aspect-ratio, hydrofoil-shaped boards used primarily in pelagic (mid-water) trawling. They are much taller than they are long, with an AR typically between $2.0$ and $3.0$.

• Rectangular V Otter Board (B): These boards have a distinct V-shape for stability on rough bottoms. Their AR is generally around $1.0$ to $1.5$, making them higher than flat rectangular boards but lower than specialized hydrofoils.

• Oval Profile Otter Board (C): These are designed to be towed over obstacles. Their aspect ratio is usually around $0.6$ to $0.8$.

• Rectangular Flat Otter Board (A): These are the traditional boards where the length is significantly greater than the height. They have the lowest aspect ratio, often around $0.5$.

• Ordering: Following this data, the decreasing order is Suberkrub (D) $>$ Rectangular V (B) $>$ Oval (C) $>$ Rectangular flat (A).

Step 3: Final Answer:
The correct decreasing order of aspect ratio is D, B, C, A.