Abstract
It is now generally recognized that an adequate instrumentation on board is very useful for the analysis of both measured-mile and service performance trials. The author was fortunate enough to attend these trials on two ships of the same service speed, about 16 knots, but with very different block-coefficients. One was a passenger-cargo liner with a block-coefficient of 0.672, the other a large tanker with a block-coefficients of 0.770. The ships were equipped with torsionmeter and pitometer log.
The results of the analysis of measured-mile trials are given and compared with the predicted power derived from tank tests. The effect of fouling and deterioration of the hull as well as the effect of weather on power and speed are established from an analysis of service data.
Most of the data were obtained in the nearly fully-loaded condition, although a less important number of observations enabled the effect of weather in the medium-loaded condition to be fairly well estimated. Information is also given on the power that can be developed in a heavy sea without damage to the ship. In the case of the large tanker, details are given of the velocity distribution within the boundary layer measured by means of the pitometer log.
Get full access to this article
View all access options for this article.