Oh dear. Going to be some sort of international obsession to build the largest fleet of tug-boats-of-war. I shutter at the thought of the three-legged arms race.
The British didn't send a single gunboat (or a single tugboat, for that matter), they sent 3 cruisers, 2 gunboats, 150 marines and about 1,000 loyal Zanzibaris. There is no way Khalid's motley crew can defeat such a force short of Act of Bat.