THE TECHNIQUE OF TRAWLING 



115 



The diameter is increased in stages, the wire being made up of a number 

 of sections of different diameter joined together to form one length. The 

 Galathea's wire, 12,000 metres long, was formed as shown in the table. 



The Galathea's i2,ooO'metre Trawling Wire. 



Diameter 



Length 



Weight in Water 



Breaking Strain 



9.3 mm. 



1 1.6 mm. 

 13.2 mm. 



14.7 mm. 



1 7. 1 mm. 

 19.6 mm. 



20.2 mm. 



21.8 mm. 



3,600 m. 

 1,750 m. 



770 m. 

 1,330 m. 

 1,730 m. 

 1,080 m. 



980 m. 



760 m. 



0.26 kg/m. 

 0.41 kg/m. 

 0.53 kg/m. 

 0.66 kg/m. 

 0.89 kg/m. 

 1. 1 8 kg/m. 

 1.25 kg/m. 

 1.45 kg/m. 



7,140 kg 

 I 1,100 kg 

 12,600 kg 

 15,600 kg 

 21,000 kg 

 25,000 kg 

 29,200 kg 

 33.900 kg 



In trawling with this wire the lowermost section, with a diameter of 

 9.3 millimetres, practically attains a straight course before the transition 

 to the next section with a diameter of 11.6 millimetres. This and all 



p 12 



30' 



50' 60' 70' 



Diagrams used for calculating the length of wire to be paid out. a. Otter trawl, b. Sledge trawl. 

 The abscissa is the angle. 



