A convoy can look like a larger and therefore easier target when imagined at close range. Across an ocean, its compact footprint need not be much easier to encounter than a single ship. Sending the same ships independently creates many more possible contacts spread across a wider area. Concentration also lets scarce escorts protect several merchant ships together. The comparison explains why convoy protection could seem counterintuitive to observers during the world wars.
Notable Point · 2:59:40-3:01:22
Why grouping merchant ships can reduce encounters at sea
An explanation of ocean scale shows why concentrating merchant ships can reduce exposure while making escort practical.