Resistance Due to Leeway and Heel
Remarkable
Sailing ships
sailing to windwards
counteract aero force
by hydro force
keel
Leeway
Angle between
Water track and bow
Resistance on Leeway up to 5°
Almost entirely due to Hydro forces
Depends on
Keel characteristics
Span
Aspect ratio
Rounded planforms
reduce drag
reduce lift
less than 5deg
Higher leeway angles
Causes separation
Called Induced DRAG
Induced resistance
Associated with Side force or lift on the hull
Induced resistance
approximately
adding induced resistance
of Hull, Keel and Rudder
Keels and Rudders
Increments in Induced Drag
Extremely tapered
Close to rectangular
Elliptical spanwise loading
Taper Ratio (l/L) BTW 0,3 and 0,4
Reduce Induced drag to 1 or 2%
Reduce Lift
Reduce forces
Effect of Sweep
Increase loading near tip
Hull becomes asymetrical
Increases wavemaking resistance