The case for a concrete convoy sloop

What vessel might make the most sense if built with a concrete hull?

A slow convoy-protection sloop is the most plausible fit, not a high-speed combatant.

Steel-reinforced concrete would make a warship much heavier than a conventional steel hull. A convoy sloop whose work does not require high speed is the most plausible role, with a suggested ceiling of about twenty knots. Cheap material and relatively straightforward repair could then matter more than acceleration or fine hull form. The hull might also react differently to torpedo damage, although that resilience remains a possibility rather than a proven result. Construction weight and practical engineering would remain substantial disadvantages. The design makes sense only as a specialised slow escort, not as a general route to fast combatants.