Why modernizing the Tennessee-class cruisers was unattractive

What if the Tennessee-class armored cruisers were modernized in 1928?

They could be rebuilt extensively, but cost, age, treaty politics, and the superiority of new cruisers make the investment hard to justify.

The Tennessee-class armored cruisers carried four 10-inch and sixteen six-inch guns, but their vertical triple-expansion machinery delivered only about 22 knots. By a proposed 1928 modernization, their hulls were already more than twenty years old. Rebuilding studies included closing the casemates, fitting oil-fired machinery for 27 knots, and replacing the main armament with triple eight-inch turrets. The cost figures read out rise from $6 million to $17 million, while the rebuilt ships would still face much newer weapons and designs. Reconstruction also threatened to take resources away from new cruiser construction. Keeping the 10-inch guns raises a treaty-classification problem, since guns above eight inches bring capital-ship restrictions into the debate. An escort-carrier conversion would require gutting the ship and replacing its engines, making a new carrier the more economical alternative in this assessment.