How a 1930s warship keel was built

How was a warship keel made in the 1930s?

It was built up from heavy steel sections and plates, often with secondary keels.

The keel was assembled from heavy steel sections and plates rather than formed as one simple piece. Many ships of the period also had secondary keels. The method resembles later sectional shipbuilding because major hull elements are built up and joined into a complete structure. The result is an engineered framework rather than a single solid beam.