Though in the past many cruisers had no means of generating electricity on board and depended on kerosene and dry-cell batteries, today electrical demands are much higher and nearly all cruisers have electrical devices such as lights, communications equipment and refrigeration. Although most boats can generate power from their inboard engines, an increasing number carry auxiliary generators. Carrying sufficient fuel to power engine and generator over a long voyage can be a problem, so many cruising boats are equipped with other ancillary generating devices such as solar panels, wind turbines and towed turbines. Cruisers choosing to spend extended time in very remote locations with minimal access to marinas can opt to equip their vessels with watermakers (reverse-osmosis seawater desalination units) used to convert sea water to potable fresh water.