1982 and 1987. Initially, the British government had hoped that the Chileans would accept a package to upgrade the ships to operate Seadart, but this was not taken up and they were transferred complete with Seaslug. The Chilean ships were later refitted with an extended flight deck in place of the Seaslug launcher. Variants There were two main variants of the Seaslug: Mark 1 (GWS.1) The Seaslug Mark 1 was powered by the solid-fuel Foxhound (390 kg fuel) sustainer motor and Gosling(145 kg) booster motors. It had a radio proximity fuze and blast warhead. The Mark 1 was a beam rider missile, meaning the target had to be continually illuminated by the directing radar, so the system was limited to engaging only the number of targets that there were radars to track and lock on. Attack Velocity: Range: Ceiling: Mark 2 (GWS.2) The Seaslug Mark 2 was based on the aborted Blue Slug programme to develop an anti-ship missile using the Seaslug missile and guidance system. The project was cancelled in favour of the "Green Cheese" missile, a tactical nuclear anti-ship weapon, but other project developments were incorporated into what became the Mark 2. It had improved low altitude performance and a limited anti-ship capability and entered service in 1971. The Mark 2 utilized an improved beam-riding guidance system. and solid-state electronics. It was powered by the Deerhound sustainer motor, with Retriever boosters. Control was by a modified Type 901M radar and it had an improved infra-red proximity fuze and a continuous-rod warhead with a smaller, , explosive charge (RDX-TNT) and an unfold diameter of about 70 feet (10 mm steel rods were used) Attack velocity: Range: Ceiling: The capabilities of the new Sea Slug Mk 2, an almost 2.5 ton missile, were much improved compared to the previous Mk 1. The boosters gave a total of about 60 tons-force, with fuel for each one (145 kg in the Mk 1), accelerating it to over Mach 2. When they separated because the extreme drag made by the rings all around the missile, the solid fuel sustainer Deerhound started to burn its of propellant (390 kg for the Mk 1) and gave about for 38 seconds. The slender missile remained at over Mach 2-2.5 until the flameout. The missile was made fully controllable about ten seconds after firing, followed by a radio-beacon while it was centered in the radar beam; and