Largest Waves at "Kiree Lighitships 



The results of observation are reported from the following 

 lightships: 



(1) FERMARNBELT Tfestern ml tic 



(2) T30r{Km'[RIFF Western North Sea 



(3) AMRro/IBWff: Eastern North Sea 



The winter 1936-37 during v/'hich the following observations 

 were made, was particularly stormy o I'lgure 15 which represents wave 

 heights observed at the lightship FEPMARNHELT (1-10-36 to 31-3-37) in 

 the western part of the Baltic Sea, show a general picture of the 

 effects of the storm^ Generally, observations were made three times a 

 day, 8 a„m., noon, and U p.m. Data is missing for certain periods 

 because the ship left its position to escape danger of freezing in. 

 According to observations from the lightship FERMARNBELT during the 

 winter 1936- 37 a vrave height of 2 meters was reached or surpassed nine 

 times, while the 3-nieter mark was exceeded only once„ The strongest 

 effect of the storm was observed on 1 December 1936= The highest 

 wave was estimated by observer II of the lightship FERKfARNBELT to be 

 3olO meters in height „ On 27 October 1936, the day when the light- 

 ship ELBE 1 capsized, maximum wave heights given by observer i of 

 lightship FEBtARNEELT were 2„5 - 3oO meters „ The same obser-vjr gave 

 2o7 meters for the maximum value on the 19 January 1937. Tfeve 

 lengths evaluated from the observed data indicate that on 1 December 



1936 the vmv3 steepness, H/l was equal to IslO and on 19 January 



1937 for wave heights of 3ol and 2.7 respectively„ 



From the lightship K)RKMRIFF observer III reports for ttie 

 afternoon of 1 December 1936 "the highest sea observed in the North 

 Sea„" The maximum vrave height was estimated at 8-9 meters » This 

 estimate must be judged on the basis of the previously made statement 

 that the heights of very high waves are readily overestimated „ 

 Measurements were not possible on this dayj in fact the lightship 

 had torn itself loose from the anchor chain. During this high sea 

 observer III counted six passing crests per minute Virhich corresponds 

 to an average period of 10 seconds and a mean vrave length of about 

 150 meters. Ihe wave length vras visually estimated at 60 meters but 

 this value must be ruled out since the wave lengths at this point 

 of observation were consistently underestimated. 



The highest waves given by observer V of lightship AJifRMEANK 

 in the winter 1936-37 (December 1936) were 5 meters in height while 

 observer \Tl gave the maximum height for /+ December 1936, Here the 

 average period was equivalent to a frequency of eight crests per 

 minute or T = 7.5 seconds. Kiis corresponds to about L = 90 meters 

 and, on the basis of the estimated wave height to a ratio hA ~ 1:13. 



