Naval Photo Interpretation 
vessel the longer her wake in proportion to her size. In 
rough sea we may notice that the normal appearance of the 
wake sometimes becomes broken and altered. 
In Fig. 4 there is an enlarged detail of a low oblique 
showing six vessels manoeuvring at high speed. They are 
turning a little to port (to the left in the picture) and are in 
rather close formation. The peculiarities of the different 
wave systems and wake patterns, however, stand out clear- 
ly enough making a correct analysis possible. 
As regards the bow waves the 'ruffle'' pattern of the 
four uppermost vessels is about the same for them all. 
The other two craft, down to the left in the picture, on the 
other hand, form quite different bow waves with ''arrow- 
head' pattern, and their two wave systems also have 
mutual differences. Viewing the wake, formed by the first 
four mentioned vessels with resembling bow waves, there 
are, however, most conspicuous differences between the 
pattern of the right-hand couple compared to the left-hand 
one. 
When analyzing the wake pattern of the right-hand 
couple, one can see how the foam of the stern wake appears 
clear white immediately under the stern, surrounded by 
frictional wake formed as white turbulance on either side 
of the afterbody. The stern wake is first sharpened into a 
narrow bottle neck, then spread out forming two side- 
streams surrounding a wide central stream of about the 
same width as the beam of the vessel itself. In verticals 
this central stream is clearly seen as a combination of 
three separate, slender streams. The left-hand couple 
has about the same bottle neck and side-stream pattern of 
the stern wake as the right-hand one. The central stream,