Estimate bulb volume, projected frontal area, and longitudinal position using empirical correlations, displacement ratios, or geometric models.
Bulb Volume: — m³
Projected Area: — m²
Enter inputs to compute.
Bulb Volume: — m³
Enter inputs to compute.
Bulb Volume: — m³
Projected Area: — m²
xb (fwd of FP): — m
Enter inputs to compute.
A bulbous bow is a protruding bulb-shaped volume located at the forward underwater part of a ship. Its purpose is to modify wave patterns and reduce resistance at design speeds.
The primary geometric properties of a bulb are its volume and projected frontal area. These parameters influence wave cancellation effects and interaction with the hull’s bow wave system.
Empirical methods relate bulb volume to main hull dimensions and block coefficient. These correlations are widely used in preliminary design stages when detailed geometry is not yet available.
In early design, bulb volume is often expressed as a fraction of ship displacement. Typical ratios range from 0.5% to 1.5% of ∇, depending on vessel type and operating speed.
When approximate bulb dimensions are known, the bulb can be modeled as an ellipsoid. This approach provides direct estimates of volume, projected area, and longitudinal position.
Tip: Bulb design should always be validated with resistance prediction methods and, where possible, model testing or CFD.