Tankers are strongly constructed and fitted out to carry bulk liquids (e.g. crude oil). The effect of liquid cargo on the stability of the vessel is considerable. Therefore, tankers have wing tanks on either side of the centre tanks and no double bottom (though, now-a-days providing double bottom is compulsory). The tanks do not extend across and breadth of the tanker as one compartment but have extra strong longitudinal divisions. Includes Gas Carrier and Super Tankers. The term super tanker, VLCC (veer large crude carrier) and ULCC (ultra-larger crude carrier) are used for mammoth tankers of over 1000,000 DWT, 150,000 DWT to 300,000 DWT respectively.