The number of merchant ships Edward III could requisition would have been envied by French commanders. There were probably 1,000 to 2,000 ships operating from English ports in the early 1330s, although few were the big wine ships preferred for naval warfare. One pair of 220-tun cogs from Great Yarmouth, John Perbroun’s La Michel and Thomas Sad’s La Garlond, were used alongside the big king’s ships on the crossing to Antwerp in 1338, but large merchant ships became less common in English waters as the Hundred Years War progressed. Only one very large merchant vessel, the 240-tun La Trinite of Hamble on the Hook, was listed among the mass of impressed merchant vessels used in the 1359 fleet.

The vast majority of English merchant ships were smaller than La Trinite. Most king’s ships were bigger than 100 tuns, but ships of this size rarely comprised more than 10 per cent of merchant fleets. Although the admirals regularly proclaimed that thirty- or forty-tun vessels were needed for fleets, ships of even this meagre size were scarce in some areas. The Admiralty of the North’s census of 1336 showed that only 104 ships with a capacity greater than forty tuns existed on the east coast. The average size of ships would shrink as the pressures and economic consequences of the war took their toll. English merchants also became more likely to invest in smaller ships in the later years of Edward III’s reign, primarily to avoid service in royal fleets. For the very large fleets of the 1340s and 1350s, English commanders resorted to small vessels. During the crossing to Antwerp in 1338 the average size of impressed merchant vessels was eighty-eight tuns. This had shrunk to thirty-eight and forty tuns respectively by the 1359 and 1370 voyages. As the biggest ships became rare, smaller vessels were used more frequently.

Most mercantile vessels were too small to be impressed except in the largest fleets. Despite working extremely hard to find shipping for the siege of Calais in 1347, the admirals found only 215 ships in the Admiralty of the North and 520 in the Admiralty of the West. The 1359 fleet was larger still, and the clerks pressured coastal communities to find vessels. Repeated investigations increased the number of suitable ships identified.