Prismatic Coefficient Calculator with Volume

Prismatic Coefficient Formula:

\[ C_p = \frac{V}{A_m \times L} \]

Prismatic Coefficient (C_p):

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1. What is Prismatic Coefficient?

Definition: The prismatic coefficient (C_p) is a dimensionless value that represents the ratio of the displaced volume of a ship's hull to the volume of a prism with length equal to the ship's length and cross-sectional area equal to the largest underwater section of the hull (midship section).

Purpose: It's a key parameter in naval architecture that indicates the fineness of a ship's hull form and affects resistance and propulsion efficiency.

2. How Does the Calculator Work?

The calculator uses the formula:

\[ C_p = \frac{V}{A_m \times L} \]

Where:

\( C_p \) — Prismatic coefficient (dimensionless)
\( V \) — Displaced volume (m³)
\( A_m \) — Midship section area (m²)
\( L \) — Length of waterline (m)

Explanation: The displaced volume is divided by the product of midship area and length to determine how full or fine the hull form is.

3. Importance of Prismatic Coefficient

Details: Lower values (0.55-0.65) indicate finer hulls better for speed, while higher values (0.70-0.80) indicate fuller hulls better for cargo capacity. It significantly impacts wave-making resistance.

4. Using the Calculator

Tips: Enter the displaced volume in cubic meters, midship section area in square meters, and length in meters. All values must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: What's a typical prismatic coefficient range?
A: Most ships range between 0.55-0.85, with high-speed vessels at the lower end and bulk carriers at the higher end.

Q2: How does prismatic coefficient affect performance?
A: Lower C_p generally means less wave-making resistance at higher speeds, while higher C_p provides more cargo capacity but higher resistance.

Q3: Where is midship section area measured?
A: At the largest underwater cross-section, typically near the middle of the ship's length.

Q4: What length measurement should be used?
A: Typically the length on the waterline (LWL) or length between perpendiculars (LBP) is used.

Q5: How is displaced volume determined?
A: Through hydrostatic calculations based on hull shape, or by measuring the weight of water displaced (1 m³ of seawater ≈ 1.025 metric tons).