At the outbreak of war, Britain had 3 formed MTB flotillas, precious few to cover the worlds largest empire. But with judicious use of what were pre-war civilian boatyards and the huge resources of their empire and help from the USA, the Coastal Forces would in 1944 have 25,000 sailors in over 2000 small craft!
On December 7th, 1941, the US Navy could only boast 3 squadrons of motor torpedo boats, or PT boats (patrol torpedo) as they were named. PT squadron 1 was based on Pearl Harbor and the 12 boats opened fire on the incoming Japanese bombers, claiming 2 planes downed for sure and others damaged
Kaiser Wilhelms vision, indeed obsession, with building a vast fleet of dreadnoughts came to nought during the Great War. He knew that his excellent fleet could not risk significant battles with the Royal Navy, it was a one-shot weapon
By 1941 there were 29 total PTs total in the US Navy, by December 43 there were 29 squadrons. Indeed, by the end of the war the small ships, PTs LCI etc. numbered 7,000 craft of 80 types.
Between the wars Japan reassessed its position with its navy, building the worlds first purpose-built aircraft carrier, the Hosho in 1921 and inventing its deadly fast and powerful type 93 24 oxygen fuelled torpedoes