The manner In which the laminar area S L diminishes as the model Reyn- 

 olds number increases is of considerable interest. The ratio of S-, to the 

 wetted' surface S of the model at rest is plotted against the Reynolds number 

 in Figure 13. For comparison a hypothetical curve has been computed for a 

 flat plate with the assumption that the Reynolds number of transition R is 

 constant at TO 6 and that there are no disturbances arising from the plate 

 edges or the water surface. Admittedly, this latter assumption is an over- 

 simplification and amounts to specifying the largest possible laminar region 

 for a given R . This computed curve is a branch of an equilateral hyperbola 

 and the curve of S T /S for the ship model has much the same shape between 

 x/L =0.35 and 0.128. In contrast, however, a wedge of the side area from the 

 bow to x/L = 0.128 remains constantly laminar between model Reynolds numbers 

 7.75 to 11.0 x 10 6 . The area S. then continues to decrease for R > 11.0 x 10 6 . 

 This constancy of S T over a range of Reynolds numbers may be attributed to the 

 stabilizing effect of the negative-pressure gradients which are known to exist 

 over this portion of the hull and also to the fact that surface disturbances 

 cannot be diffused rapidly enough to affect the region forward of Station 2. 

 The fact that negative-pressure gradients extend over at least the first 10 



2.0x10 4.0 



8.0 10.0 12.0 



Reynolds Number R - ^- 



Figure 13 - Variation with Reynolds Number of Area 

 Covered by Laminar Boundary Layer 



