Performance of Partially Submerged Propellers 



9. Dobay, G.F., "Hydrofoils Designed for Surface Ventilation — An Experi- 

 mental Analysis," SNAME, May 1965 



10. Hoerner, S.F., "Fluid Dynamic Drag," published by the author, Midland 

 Park, N.J., 1965 



11. Lindenmuth, W.T., and Barr, R.A., "Study of the Performance of a Partially 

 Submerged Propeller," Hydronautics Incorporated Technical Report 760-1, 

 July 1967 



12. Ward, L.W., "Methods for Estimating Impact Forces on Ship Appendages," 

 Davidson Laboratory Report No. 616, Dec. 1956 



13. Burt, F.S., "New Contributions to Hydroballistics," Advances in Hydro- 

 science, Vol. 1, 1964 



DISCUSSION 



H. Volpick 



Brown Bros. & Co. Ltd. 



Edinburgh, Scotland 



In the historical introduction of this very interesting paper, the authors 

 have remarked on the use of partially submerged propellers years ago on 

 rivers and lakes. As a former member of the Denny Ship Model Basin in Dum- 

 barton (Scotland), which was liquidated in 1963 — at least in name — with the 

 entire firm of Denny, I should like to mention that already in the 1920' s ship 

 propulsion of this type for specific river application in India and Burma was 

 evolved by Denny. After extensive model tests, the first experimental vessel, 

 the Meccano, was built, and full-scale experiments were continued. One of the 

 first commercial vessels, the Chuchow, of about 100-ft length had two large, 

 slightly submerged propellers, or "vane wheels" as they were called, at the 

 stern, turning at about 60 rpm through a gearbox. Before this vessel was 

 finally shipped out East, further extensive tests were carried out on the River 

 Clyde at different immersions of the vane wheels, which were four-bladed, of 

 large area, and with ordinary circular back sections. These trials showed 

 that the predictions from the model tests were reasonable, and that the optimum 

 propulsive efficiency coincided with an immersion coefficient (i.e., immersion 

 of wheel/diameter) of between 0.30 and 0.35 falling off rapidly with higher im- 

 mersion, due to increased drag. This peak efficiency was over 0.45, which did 

 not compare unfavorably with the figure of 0.50- 0.55 for customary paddle 

 propulsion. 



The largest vessel of this type built by Denny was the M. V. Stanley, a river 

 cargo vessel which operated from 1929 onward on the Congo river. With the 

 advent of high-speed Diesels and directly coupled, fast-turning, small, fully 

 immersed propellers, vane-wheel propulsion went out of use. However, the 



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