Hydrofoils Running Near a Free Surface 
A ; 
A eee 
cos 
179 
The parameter for the influence of the water surface Kz for parallel submerged foils equals 
the term 
C uw 
ees 
Lo 
as shown in Fig. 30. For dihedral foils or slanting flat foils of constant profile length, the 
tips of which run at the depths h, and hy (hy > hy), a mean value valid for the whole foil can 
be found by integration of the term 
Cc w 
L 
ee, 
Che 
over the depth of submergence: 
1 hy 
By Wash le 
K; = i, = joer (h)dh. 
SHR Snes Sam NN Rg 
015 
01 
7 2 3 
h —e 
Fig. 30. Dependence of the decrease of lift and the 
gradient of the lift decrease on the depth ratio 
(18) 
