NON-ROLLING PASSENGER LINERS. 105 



panied with a "bad angle of attack," causing- a large extra power consumption. A 

 stabilized ship is practically self-steering. This comes as a sort of a bi-product of 

 stabilization, the stabilized ship requiring practically no helm, regardless of weather. 



But there is a still greater source of power waste in rolling ships. As the hull 

 constantly oscillates back and forth, its form-lines encounter and constantly displace 

 laterally, with extra friction of impact, hundreds and even thousands of tons of 

 water, and this persists, going forward with every roll. This, in connection with the 

 extra wetted surface involved, added to the extra stream-line losses and skin fric- 

 tion inpingement, especially when bilge keels are present, amounts to losses of very 

 great magnitude in terms of actual horse-power wasted. Model experiments and re- 

 sulting calculations indicate that these losses are much higher than have been sup- 

 posed. Fig. 8, Plate 44, graphically expresses by the shaded area the tremendous 

 increase in volume of water disturbed by a rolling vessel. For a 15,000-ton vessel 

 at 18 knots — away inside the maximum roll — this loss may easily reach from 1,000 

 to 1,200 horse-power, and this power is absolutely dissipated and wasted. 



Just here the stabilizer steps in with a saving of nearly all of this — practically 

 the entire amount, minus the small and comparatively insignificant quantity of power 

 that is required to keep the gyro wheel spinning in a vacuum. In the course of a 

 very few voyages this power saving in terms of fuel saving amounts to enough to 

 pay for the entire stabilizing equipment. 



Very full corroboration of this is found in the service performance of a fast 

 passenger and cargo ship, by taking ten consecutive trips over the same course in 

 the same direction with almost identical load conditions and under conditions of con- 

 stant propeller revolutions. These trips are sufficiently long, 4,600 miles, to be con- 

 vincing in the results shown. These data have been plotted in revolutions per knot 

 (see Fig. 9, Plate 44) and give interesting and positive indication of the retarda- 

 tion of the ship owing to weather conditions. A very great amount of the losses 

 in headway due to the retardation efifect of the disturbances discussed above will 

 be entirely eliminated by ffill stabilization. Let us examine what this means in 

 dollars. Suppose the operating expense per 24 hours to be $6,000. The extra ex- 

 pense — that is, the expense over and above the average — in the stormy months 

 amounts to not far from $100,000. This, taken with the amount saved through 

 elimination of bilge keel losses, develops an earning capacity of the stabilizer of not 

 far from 100 per cent per annum. All of this is over and above the many other im- 

 portant gains, both direct and indirect, resulting from the stabilizer installation. 



The stabilizer achieves another economy of very great significance to both the 

 operator and the passengers of fast ships. This is the practical avoidance of the 

 necessity for slowing down ships in stormy weather or when heavy seas prevail, the 

 ships being able to make practically the same time under storm conditions. This 

 has been repeatedly demonstrated and is a result so startling that, when first experi- 

 enced, it has often been claimed a:s an original discovery by the skippers of sta- 

 bilized ships. 



So insignificant are the stresses required to prevent all rolling that it is in- 



