Resistance Due to Leeway and Heel

Remarkable

Sailing ships

sailing to windwards

counteract aero force

by hydro force

keel

Leeway

image

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%

image

Reduce Lift

Reduce forces

Effect of Sweep

Increase loading near tip

Hull becomes asymetrical

Increases wavemaking resistance