Statistical displacement-ship resistance prediction based on Holtrop & Mennen component breakdown: frictional resistance, hull form factor, appendages, wave resistance, bulb pressure, transom pressure, correlation allowance, propulsion factors and propulsion power prediction.
Inputs
Method and environment
Propulsion and engines
Final calculated result
Required installed power
—
kW = PS / margin
Appendage resistance RAPP
—
kN
Wake fraction w
—
estimated
Thrust deduction t
—
estimated
Relative rotative ηR
—
estimated
Hull efficiency ηH
—
(1-t)/(1-w)
Status: —
Charts
Speed vs effective power PE
Red marker = current speed.
Speed vs required installed power
Required installed power = shaft power / MCR margin.
Resistance components versus speed
Component curves show how the Holtrop total is assembled.
Formula summary
TOTAL RESISTANCE:
RT = RF(1+k1) + RAPP + RW + RB + RTR + RA + RBTO
FRICTION:
Re = V L / ν
CF = 0.075 / (log10(Re) - 2)^2
RF = 0.5 ρ V² S CF
WETTED SURFACE:
S = L(2T+B)√CM [0.453 + 0.4425CB - 0.2862CM - 0.003467B/T + 0.3696CWP] + 2.38ABT/CB
1984 FORM FACTOR:
1+k1 = 0.93 + 0.487118 c14(B/L)^1.06806(T/L)^0.46106(L/LR)^0.121563(L³/∇)^0.36486(1-CP)^-0.604247
LR = L(1 - CP + 0.06 CP lcb/(4CP - 1))
c14 = 1 + 0.011 Cstern
WAVE RESISTANCE:
Low/moderate Fn uses Holtrop formula RW-A. High-speed Fn > 0.55 uses the 1984 re-analysis RW-B. Between Fn 0.40 and 0.55, the calculator interpolates between both equations.
POWER:
PE = RT V
ηH = (1-t)/(1-w)
PS = PE / (ηO ηR ηS ηH)
Required installed power = PS / MCR service margin