All sea-based on-growing farms need a boat (Fig. 21.32). In the past, small boats of polyethyleneor fibreglass with an outboard motor were often used. Today, larger boats of steel or aluminium with a working deck are becoming increasingly common as a result of the trend towards using larger cages and sites with more feed and heavier equipment. Faster boats are more common than previously, and speeds of up to 15–20 knots are normal. One reason for this is that the distance from the coast is increasing and more exposed water is being used for farming. Catamarans with wide decks and lengths in excess of 10m are much used today. It is common to have a crane on the boats for handling nets and feed sacks.