It was while operating off the Iberian Peninsula that Collier devised a need for an improved type of ships' boat. He developed a design based on elements of both a whaleboat and a jolly boat, and had one built for him at Plymouth Dockyard. The boat proved extremely useful after tests aboard the "Surveillante", especially at being able to land safely on a flat beach to give close support. Collier further modified it by installing a howitzer in the bows, and soon boats of its type were being requested by other captains for their ships. In 1813 Collier succeeded Sir Home Popham in commanding the north coast squadron, Spain. He and a small squadron supported General Arthur Wellesley and General Sir Thomas Graham in the capture of San Sebastián and the siege of Bayonne.