International Shipbuilding Progress

In general it appears that the resistance caused by well-placed appendages can be split up into frictional resistance and wave resistance.

By using the Lap-Troost three-dimensional extrapolator (1), (2) it is possible to separate these two parts. When extrapolating to the actual ship, the scale-effect can then be taken into account automatically. Results of tests with the Lucy Ashton model family fitted with appendages demonstrate the correctness of the new method, as do N.S.M.B. tests on models with and without appendages. Finally a short survey is given of the factors which influence the properties of bossings and shaft brackets.

The paper describes many failures that have occurred in service in marine steam and Diesel propelling machinery. Where possible, details are given of either the temporary or permanent repairs that were effected. The paper is well illustrated and should appeal to practical engineers.