STABILITY OF LIFEBOATS. 

 Dynamical Stability — Light Condition. 



137 



Somewhat startling results were obtained with the collapsible boat. This 

 was a new boat, obtained with the customary guarantee and was supposed to be 

 in all respects ready for immediate service. It was of the dimensions given in the 

 table and rated to carry 54 persons. When the inclining experiments in the light 

 condition were made the boat did not come to a position of equilibrium after the in- 

 clining weights were moved to one side, as the plumb-bobs showed a slow but con- 

 tinually increasing angle, the reason being that water was slowly leaking into 

 the pontoon. The boat was hauled out and a few days later re-launched, hoping that 

 it had swelled tight ; but with the same result. A position of equilibrium was even- 

 tually reached after several hours in the inclined position and the center of grav- 

 ity determined. 



When it came to the loaded condition the boat sank completely with 43 

 persons aboard, so that it was decided to accept for the load condition a less load- 

 ing, one which would permit of the craft remaining afloat. Sixteen persons re- 

 sulted in a freeboard oi ij4 inches to the top deck and this was the load used. 

 The center of gravity for this and the light conditions are indicated in Plate 78 

 and the table. The curve of righting moments, when loaded with 16 persons, is 

 shown on Plate 80 and it is interesting to note that the angle of vanishing stabil- 

 ity is three degrees. The curve of dynamical stability is so small that it could not 

 be shown on Plate 82. 



The failure of this boat to live up to a higher percentage of its requirements 

 was undoubtedly due to water leaking into the chamber between the decks and is 

 an excellent illustration of what is bound to occur when water obtains access to 

 the single buoyant compartment of a boat of this type. The essentially vicious 

 feature is that while water leaking in entirely eliminates the craft's stability and 

 seriously impairs its buoyancy, the leakage is unknown and cannot be bailed out as 

 in an open boat. Moreover, any wooden construction subjected to the ordinary 

 weathering and wear encountered on the decks of ocean-going vessels will not and 

 cannot be expected to remain watertight. The bulwarks are not intended to be 



