The Navy getting all the steel? All of the capital ships had already been launched (B&T, S&G, and GZ) as had all 5 of the Hippers... outside of some for u-boats and escorts, the navy didn't lay down anything substantial in 38 or 39
There were gigantic shit loads of steel being poured into the west wall and the oder line though; as the small german bunker design of the period required 2 5-tonne armored plates, and the larger bunker required 2 19-tonne armored plates... and both lines had many bunkers
However its is highly likely that the steel was of a different spec for that used in ships. Plus limitations on things like plate sizes at the rolling mill, that sort of thing.
In the short term, these things arent just interchangeable...and even if they were, the skilled workers cant just be taken from the farm (as were some of the West Wall workers...