With regard to beach groins, opinions as to their proper length were 
far apart. Groins of limited length were considered adequate on dry as 
well as on wet beaches, while groins reaching beyond the first sand reef 
were proposed when sand movement was the main problem involved. In the 
Baltic Sea this reef is located approximately 100 meters, and on the North 
Sea (Sylt Island) 300 meters, from the shore line. Only economic reasons 
account for the fact that such proposals regarding groin length were not, 
or only in part, accomplished. The construction as well as maintenance 
cost increased considerably with the length of the structure. 
e. Elevation of Groin Crest - With regard to the most efficient 
elevation of the groin crest, a variety of ideas were found to exist. Some 
authors had the attitude that a horizontal position of the crest was cor- 
rect, others held that a certain minimum margin above the beach elevation 
was necessary; still others constructed groins high above the beach, to 
the final elevation which they desired to achieve when the sand-catching 
capacity of the structure would be reached. New proposals point toward 
structures built so that they would follow the profile of the beach. This 
is possible only in the downward direction. During periods of heavy sand 
movement these groins would be buried. 
f. Groin Groups - Lee Erosion and Groin Spacing - Wherever groins 
were erected, it was found that single groins never met the requirements 
and that more of them were always needed to provide protection or mainten- 
ance of beaches or to retard shore degradation. Always in the lee of surf 
currents (adjacent downdrift areas) new damages were found, requiring the 
expansion of groin groups. This development logically led to a "Totality 
System", meaning that the entire coast had to be protected by groins. 
However, Hansen (1938), considering the natural conditions of sand behavior, 
believed such a limitless procedure should be rejected not only for func- 
tional but also for financial reasons. 
In a series of investigations regarding methods to alleviate the lee 
erosion problem, no satisfactory solution had yet been found. This problem 
played a considerable role in deciding the terminal limits of a group of 
current groins as well as for all beach groins in general. 
Within a group of groins, spacing of the structures was determined 
in many ways; it varied from one to three times the length of the groins, 
without any distinct recognized system. As during the course of de- 
velopment, lengths of the groins were considerably increased in com- 
parison to original concepts, a definite length-spacing relationship could 
not be derived on the basis of available engineering experience. 
g. Direction of Attack (Groin Alignment) - A number of authors 
have held it appropriate to place the heads (outer ends) of a group of 
groins in a line conforming to the direction of current flow. In dealing 
with current-deflecting groins, this attitude is unamimously accepted as 
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