A speedboat is a small boat built to go fast: a light body, an open top, seats for a handful of people, and an engine far bigger than its size suggests. It is a pleasure thing — you take one out on a lake or along the coast for fun, or to water-ski behind, or because you can afford one and want people to see it. That last part matters. In English, 'speedboat' carries a whiff of money and holiday and showing off. It appears in films with rich villains and in adverts for expensive resorts. It is not the word for a working boat, however fast that boat goes. A fishing boat, a ferry, a police launch, a lifeboat — none of these are speedboats, even at high speed, because the word is about being built for speed as the point. Rescue and police services say 'launch' or 'patrol boat' instead. As a verb, 'to speedboat' exists but is genuinely rare; you can say 'they speedboated across the bay', and people will understand, but 'they took a speedboat across the bay' is what a native speaker would actually say. Prefer the noun.