Savitsky Planing — Quick Mode

Planing resistance using friction (ITTC ’57) + pressure term with user-specified trim & wetted length.

Enter a positive number.
Enter a positive number.
Enter a positive number.
0–45°.
0–10° typical for planing.
Used for Fn and plausibility checks (optional).
0.1–1.0.
Seawater ≈ 1025.
Typical 0.006–0.012. Multiplies tan²θ·cosβ.
Adds to ITTC ’57 Cf.
Result

Total Resistance RT: — kN

Delivered Power PD: — kW

Friction Coeff. Cf (ITTC ’57): —

Pressure Term Cp: —

Reynolds Re: —

Froude Fn,l (based on l): —

Enter speed, b, l, β, θ and press Calculate. This quick mode assumes:
  • Wetted area \(S \approx b \cdot l / \cos\beta\)
  • Friction: ITTC ’57 on characteristic length \(l\), plus roughness ΔCf
  • Pressure/induced: \(C_p = k_p \tan^2\theta \cos\beta\)
  • RT = 0.5 ρ V² S (Cf + Cp)
Report: Savitsky Planing — Quick Mode
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Notes & Next Step

This is a **quick estimator** with user-defined trim & wetted length. It’s useful for sensitivity & early sizing.

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