Rapidly rising prices for steel plate in China may be taking the edge off the financial performance at some Chinese shipbuilders. But it will take a lot more than that to undermine shipyards' dramatic expansion plans aimed at ensuring the country's builders produce more ships than any other nation by 2015. In the short run, however, the country's relatively inexperienced builders seem to have failed to read the steel supply signs. They have found themselves caught out by a number of factors driving up ship steel prices. These have risen by almost 60% over the last 30 months or so and now stand close to $400 a ton. On the one hand, soaring…