Shear Stress and Pressure Distribution on a Shtp Model 
B remained less than about 8.5° on all streamlines except in 
some local regions near the stern on the keel and waterline, Here 
the transverse section curvatures are very large and the boundary 
layer approximation is not valid anyway. 
Note that equations (2) and (3) correspond to the axisymme- 
tric boundary-layer momentum-integral equations for a body of 
revolution with local radius r if r is defined by 
] dr 
r el ek 
The dominant three-dimensional effect on slender ships is simply 
the streamline convergence and divergence represented ty the equi- 
potential line geodesic curvature Fe 
Any potential flow that supplies the streamlines and invis- 
cid velocity distribution thereon can be used with equations (3) and 
(4), but we have used the very simple zero Froude number, slender- 
body potential flow theory given by Tuck and von Kerczek” in con- 
junction with the surface equation for the hull described in von 
Kerczek and Tuck . This combination seemed to give fairly good 
results for the LUCY ASHTON when compared to the double-model 
experiments of Joubert and Matheson, We used exactly the same 
procedure for the Series 60 block 60 calculations and will compare 
the results to model experiments in a towing:tank, The extension 
of the Tuck-von Kerczek slender-body potential flow program to 
include free-surface effects is underway. We have used the zero 
Froude number potential flow because of its availability and the ex- 
pectation that wave effects on the boundary-layer flow will be rela- 
tively minor on the lower portions of the hull, This calculation will 
serve mainly to illustrate the suitability of the Cumpsty-Head- 
Smith ‘’~ boundary layer method for moderate block-coefficient 
hulls, 
THE MODEL, EXPERIMENTAL SETUP, AND PROCEDURES 
The ship model used was a 20-foot Series 60, block 60, 
wood model, The name ''BRIAN BORU" was given to the model as a 
counterpart to the British research ship model ''LUCY ASHTON", 
A photograph of the model is shown in Figure 1, The body plan is 
shown in Figure 2, A slight hull modification aft of station 18 (which 
preserved sectional areas) was made to accommodate a propeller 
shaft used earlier for propulsion and vibration experiments, This 
1969 
