Want to kill small boats ...

... the Brits seem to have a solution for that. Via gCaptain;

Three millimetric wave operational Brimstone missiles were launched in a rapid salvo of less than a second against a simulated attack formation of five representative FIACs. The three missiles independently acquired and engaged their respective targets at a distance between 4km and 5km (constrained by range safety); direct hits resulted in extensive structural damage to the three leading vessels, including one travelling at around 20 knots. The missiles were launched from a surface trials platform using a Brimstone triple rail launcher in conditions of sea state 3.

Brimstone is being proposed by MBDA UK as a surface attack missile for deployment within the Sea Spear system against FIACs and other small surface threats in all weather environments. As an effective maritime Force Protection capability, it rapidly provides significant utility beyond the range of medium calibre naval gun systems. With a range of deck-mounted launcher options, from single to six-pack configurations, the system’s very small footprint gives it a high level of deck positioning flexibility making it suitable for small vessels such as Fast Attack Craft as well as much larger vessels such as auxiliary ships.