Launching Concrete Boats Bottom Up 



Norwegians are shipbuilders of old. Now they've 

 devised a new way of building and launching vessels 



LAUNCHING a two -hundred -ton 

 concrete vessel bottom up may 

 sound fantastic, but it has recently 

 been done 

 with success 

 by a ship- 

 building 

 company in 

 Norway. 

 The vessel 

 was a rein- 

 forced con- 

 crete lighter 

 (concrete 

 strength- 

 ened by a 

 skeleton of 

 steel strips), 

 and consis- 

 ted of an in- 

 ner hull of 

 wood which 

 served as a 

 mould for 

 the whole 



structure. When completed, there rested 

 upon the launching ways the inner 

 wooden mould, divided into watertight 

 compartments, and the outer concrete 



Though launched bottom 

 form inside, the big boat 



hull, both bottom up. An inner compart- 

 ment was left open at the bottom, so 

 that water entered as the vessel left the 



ways, the air 

 escaping 

 through 

 pipes in the 

 hull. When 

 this com- 

 partment 

 was com- 

 pletely 

 flooded', the 

 water then 

 reached the 

 level of the 

 two upper 

 side com- 

 partments, 

 causing the 

 boat to lose 

 its buoyancy 

 and su b - 

 merge to a 

 position of 

 unstable equilibrium. In this position,. 

 a slight list to one side caused the boat 

 to heel over completely and float to a 

 normal position. 



side up, and with a wooden 

 slid smoothly into the water 



Position A shows the boat just 

 entering the water, the wooden 

 form inside, and all of its water- 

 tight compartments full of air. 

 In position B — water has entered 

 the center compartment and also 

 those along the bottom, the air 

 escaping through vents. At C 

 — the two lowest compartments, 

 closed to the water, are buoying 

 up on the boat and causing it 

 to turn over. Drawings D and 

 E show further stages. The 

 water is afterward pumped out 



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