Ambush's nuclear reactor will not need to be refuelled during the boat's 25-year service. Since the submarine can purify water and air, she will be able to circumnavigate the planet without resurfacing. The main limit is that the submarine will only be able to carry three months' supply of food for 98 officers and ratings. The Astute-class fleet submarines are designed as the most stealthy Royal Navy submarines in history. Ambush will carry a mix of 38 weapons in six 21-inch (533 mm) torpedo tubes; * BGM-109 Tomahawk Block IV cruise missiles. Range of . * Spearfish torpedoes.