What specialist minesweepers add to converted trawlers

Were purpose-built minesweepers worth building when converted vessels could do the work?

Conversions supplied numbers for routine missions, while specialist vessels handled difficult tasks and needed to be built before wartime demand made rapid construction impractical.

Converted vessels filled many gaps in the First and Second World Wars, particularly when numerous routine missions needed coverage. An approximate 80/20 division illustrates the distinction: conversions could perform much of the work, while specialists were needed for the difficult remainder. Purpose-built ships were therefore worth acquiring in peacetime, when there was time to produce capabilities that could not be improvised quickly during war. Wartime expansion could then draw on trawlers and other vessels already available to convert. Britain and Japan made extensive use of converted trawlers. Other American assets reduced the need for equivalent mass conversion, although greater use against submarines off the US east coast remained an arguable option. Leaving more vessels in fishing also helped preserve the American food supply.