“Federal government helped destroy Southern shipping and ship building.”
What legislation did the Congress of the United States pass that impacted Southern shipbuilding.
Southern shipbuilding failed to keep up with the changes in ship construction that started in the 1840s. They could still build small and medium sized vessels out of wood with sails. The rest of the shipbuilding industry was converting to iron framed, iron plated and steam driven ships. the ship builders in the South did not have the technology to make the change and were reluctant to make the financial investments necessary to convert their yards for wood hull/sail powered ships to ships built with iron hulls and steam propulsion. The Federal Government had little to do with this set of circumstance.
I wouldn't take Southern complaints about shipping and shipbuilding at face value. There were Southern shipping companies, as well as companies with offices in the South, the North, the Border States, Britain and Europe that it would be hard to characterize as entirely of one region. Southerners complained that US laws closed US coastal shipping to foreign shipping companies. If those laws were repealed, it might have benefitted planters, but would have done little or nothing to encourage native Southern shipping and shipbuilding.
I'll link you to PeaRidge's excellent synopsis of what the government did which impacted Southern shipbuilding.
https://freerepublic.com/focus/news/3443027/posts?page=929#929