The Bruce Number calculator computes the ratio of the sail area of the boat to its displacement in the water. The Bruce Number, also known as the Bruce Roberts Formula, is a metric used in yacht design to assess the relative seaworthiness and stability of a sailboat. It's named after Bruce Roberts, a prominent naval architect who popularized the formula.
INSTRUCTIONS: Choose units and enter the following:
- (SA) Total Area of Sails
- (D) Boat Displacement
Bruce Number (BN): The calculator returns the Bruce Number as a real numbers.
The Math / Science
The formula used for the Bruce Number in this calculator is:
`BN = sqrt(SA)/root(3)(D) = (SA)^(1/2) / (D)^(1/3) `
where:
- BN = Bruce Number
- SA = Total Sail Area
- D = Displacement of Boat
http://www.nuomo.com/boatSadBruceCalculator.htm
The Bruce Number is essentially a measure of the boat's form stability, indicating how resistant it is to capsizing. A higher Bruce Number suggests greater stability, while a lower Bruce Number indicates less stability.
However, it's essential to note that while the Bruce Number can provide insights into a boat's stability characteristics, it's just one of many factors to consider in yacht design. Other factors such as hull shape, ballast, center of gravity, and sail plan also significantly influence a boat's stability and seaworthiness.
Designers and sailors often use the Bruce Number alongside other metrics and considerations to evaluate a boat's overall suitability for specific sailing conditions and purposes.
Displacement
Displacement, in the context of a boat or a ship, refers to the weight of the volume of water that the vessel displaces when it is floating in the water. It is essentially the weight of the water that is "moved aside" by the hull of the boat when it is floating or submerged in water. Displacement is typically measured in tons (or tonnes) or in pounds (or kilograms) depending on the size and type of vessel.
Types of Displacement:
- Light Displacement: The weight of the boat without any cargo, fuel, crew, or provisions.
- Normal Displacement: The weight of the boat fully loaded with crew, fuel, cargo, and provisions.
- Loaded Displacement: Similar to normal displacement, but also including the weight of additional equipment, stores, and water.
Displacement is important because it affects the boat's buoyancy (ability to float), stability, and overall performance in the water. It is a crucial factor in determining a vessel's design, capabilities, and seaworthiness.
Displacement can be calculated using various methods, including direct measurement (placing the boat in water and measuring the volume of water displaced) or through more complex calculations involving the boat's dimensions and hull shape.
Displacement in boating refers to the weight of the water displaced by the boat's hull when it is floating or submerged, and it plays a significant role in determining many aspects of a vessel's design and operation.
Sailing and Navigation Calculators:
Bruce Number: Computes the ratio of the square root of sail area to the cube root of displacement of a sail boat- Sail Area / Displacement Ratio: Compute SA/D ratio for sail boats.
- Displacement-Length Ratio: Computes a metric to describe how heavy a boat is in relation to its waterline.
- Capsize Screening Formula: Computes a metric to describe a boat's stability in rough seas.
- Vessel Displacement Volume: Computes the cubic feet displacement associated with the weight displacement.
- Weight of Seawater: Computes the weight and mass of a volume of seawater.
- Time to Sink: Compute the time it takes for a breach (water in) to surpass the displacement of the boat.
- Haversine Distance (decimal degrees): Compute the Distance Between two Points on the Earth (Great Circle Arc)
- Haversine Distance (Degrees, Minutes and Seconds): Compute the Distance Between two Points on a Sphere (Great Circle Arc) using degrees, minutes and seconds verses decimal degrees.
- Rhumb Line Azimuth: Computes the azimuth heading one can navigate for a path that crosses all meridians of longitude at a constant angle.
- Rhumb Line Distance: Computes the distance traveled between two points on the globe if traveled via a rhumb line.
- Correction Angle:
navigation equation that compensates for air or water currents. - Decimal Degrees: Compute decimal degree angles from degrees, minutes and seconds,[CLICK HERE].
- Nautical Travel Cost: Computes the total cost to travel a distance based on the cost rate and distance traveled.
- Travel Time between Coordinates: Compute the time to travel between two location (latitudes and longitudes) based on a average speed
- Distance to Sea Level Horizon: Computes the distance to the horizon from a specified height using a spherical model the mean spherical radius of the Earth