After "UB-5"s sister boat pioneered a route around past British anti-submarine nets and mines in the Straits of Dover in late June, boats of the flotilla began to patrol the western English Channel. , "UB-5", and soon followed with patrols in the Channel, but were hampered by fog and bad weather. Even though none of the boats sank any ships, by successfully completing their voyages they helped further prove the feasibility of defeating the British countermeasures in the Straits of Dover.