Armed tugs against U-boats

Is there any truth to claims that Britain used tugboats to sink U-boats during World War II?

Some tugboats were armed for convoy and harbor security and could carry depth charges. Cable tactics were practiced, but the discussion does not establish a successful U-boat sinking by that method.

Some tugboats were armed in a similar spirit to requisitioned trawlers, especially for coastal convoys and harbor security. They could carry depth charges and respond when a submarine entered the area. Crews also practiced using towing cables to snag and drag a submerged boat. The explanation contrasts German submarines making about seven knots underwater on electric motors with the greater speed and pulling power of large tugs. A pair of tugs holding a cable could therefore make escape difficult if they caught a boat. No successful cable attack is claimed, so this remains a proposed tactic rather than a confirmed sinking method.