For selected apparent-wind speed V, air density ρ, total sail area A and aggregate drive coefficient Cd, this calculator evaluates conditional drive pressure qCd = ρV²Cd/2 and conditional aggregate drive force F = qCdA. Cd is an input, not a predicted aerodynamic coefficient.
Selected Aggregate Sail-Drive Model
Compare conditional aggregate sail-drive force for selected apparent wind, effective area, coefficient and density.
Equation Used
- Apparent wind is steady and converted from knots to m/s.
- Total area and aggregate drive coefficient are selected effective values.
- All sails are represented by one conditional resultant drive component.
- Force direction, stability, hull resistance and structural loads are excluded.
The reference index is not a limit or rating.
Connected normalized schooner rig
The animation shows a hull, stepped fore and main masts, booms, stays and sails whose corners attach to those support points. Moving wind marks and the force arrow respond to the selected aggregate model.
The drawing is normalized and does not represent a particular vessel, sail cut or reefing state.
What the calculator determines
Select apparent wind, total effective sail area, an aggregate drive coefficient and air density. Outputs are conditional force in newtons and pounds-force, conditional pressure and force relative to the documented default reference case.
It does not predict Cd, force direction, heel, leeway, stability, speed, mast compression, sheet load or safe sail plan.
Selected aggregate force identity
V = 0.514444Vkn, qCd = ρV²Cd/2, F = qCdA and Flbf = F/4.4482216153. Reference index is 100F/Fref, where Fref uses 16 kn, 650 m², Cd = 1.1 and ρ = 1.225 kg/m³.
Selected-input example
At the documented defaults, conditional aggregate drive is about 29.6 kN and the reference index is 100% by definition.
Scope and design boundary
This is a selected resultant-force comparison, not a sail-performance or rig-load model. Real analysis requires apparent-wind angle, sail-specific coefficients, interaction, reefing, center of effort, hull resistance and stability.
Unsupported vessel, performance, material, failure, maintenance and operating claims are removed.
Questions
Is Cd calculated?
No. It is selected.
Is the force aligned with the boat?
The output is a selected aggregate drive component; direction is not solved.
Does the reference index represent a limit?
No. It is only comparison with the documented default case.
Can this size rigging?
No.
References & Further Reading
- Wikipedia contributors. Schooner. Wikipedia
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