MARITIME – PROPULION & PERFORMANCE CALCULATOR
Propeller Area Ratio
A precise tool.
What is the Propeller Area Ratio & How does it work?
The expanded blade area ratio (EBAR) quantifies the proportion of a propeller’s blade surface that is effectively “swept” through the water, providing insight into thrust generation and cavitation potential.
A higher EBAR indicates larger blade area relative to the propeller disc, which can improve low‑speed thrust but may increase drag at higher speeds. Designers balance EBAR with other parameters such as blade count and skew to meet performance goals.
The ratio is calculated from the propeller’s geometric dimensions—diameter (D) and pitch (P). Because both terms share the same units, the resulting EBAR is dimensionless, simplifying comparison across different propeller sizes.
EBAR = \frac{4P}{D}
EBAR = Expanded Blade Area Ratio
Parameters
Result
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Frequently Asked Questions
What is the expanded blade area ratio (EBAR)?
The EBAR quantifies the proportion of a propeller's blade surface that is effectively swept through the water, indicating thrust generation and cavitation potential.
How does a higher EBAR affect propeller performance?
A higher EBAR indicates larger blade area relative to the propeller disc. It can improve low-speed thrust but may increase drag at higher speeds.
Why is balancing EBAR important in propeller design?
Designers balance EBAR with other parameters like blade count and skew to achieve optimal performance for specific speed ranges and operational conditions.
Can you explain the relationship between EBAR and cavitation?
A higher EBAR can increase cavitation potential due to larger blade surface area, which may lead to air bubbles forming in the water around the propeller blades.
What factors should be considered when calculating EBAR?
When calculating EBAR, consider the propeller's blade area, disc area, and operational speed range to ensure optimal performance and efficiency.
Results are for informational purposes only and do not constitute professional advice.