I just found the bug that was in my propulsion calculation program. I had not been sure if it was a residual resistance table problem or a program bug. It turned out to be caused by a bug. I had the columns in the residual resistance table switched between where it was initialized and where it was used. I may still have table issues, but I will first have to reenter my residual resistance data, so that I can test.
I have found the book Japanese Cruisers of the Pacific War to be extremely useful. It is perhaps the best ship book, ever. The book gives the data necessary to to do propulsion calculations. I am using the data for the light cruiser Nagara for debugging purposes. I should see something like 90,000 SHP to achieve a speed of 35 knots, at a normal displacement. The Nagara was nominally 5,500 tons. This is the data I am using:
- displacement: 5,492.13 tons
- length on the waterline: 520ft
- beam: 46.5ft
- mean draft: 15.875ft
- Cp: 0.619
- Cm: 0.809
- Displacement-Length Ratio: 39.0599
- Beam/Height ratio: 2.92913
The 5,500 ton light cruisers were very destroyer-like. Their stern was wide and round, similar to a destroyer, and the machinery was that of two destroyers, as a high-output plant with light weight was needed to achieve 90,000 SHP in such a small ship.
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