The trawlers were constructed at shipyards along the Saint Lawrence River and in the Great Lakes. The crews of the vessels were sent inland from Halifax, Nova Scotia where they had trained. Twenty-two trawlers were constructed and sent to Quebec City to be completed and commissioned before the Saint Lawrence River froze over during the winter at the end of 1917. Once completed and commissioned, the vessels were then sent on to Sydney, Nova Scotia to join the East Coast patrol fleet. However, none of the vessels were completed in time to take part in the 1917 shipping season. This was due to construction delays as the American war effort, which had begun to pick up its pace, began to recruit Canadian workers. This caused work shortages at the Canadian yards. The majority of the trawlers that had arrived at Quebec City were laid up for the winter there, most requiring further work. The ice on the Saint Lawrence River prevented the trawlers from clearing the river until May 1918. In December 1917, the British government sought to expand the shipbuilding contracts in Canada. Alongside a large merchant ship construction programme, the Admiralty ordered a second batch of trawlers from Canadian shipyards. Designated Lot B, they were intended to be delivered by Fall 1918, but a shortage of labour, equipment and material led to delays. The steel required to construct boilers and hulls was delivered as late as August 1918.