重载船（Heavy-lift ship）也称大件运输船，是专门用于运输不可分解、特别巨大、正常船舶无法承运的载荷，而特别打造的特殊用途货船。这类船只又可分为两类：半潜船（semi-submersible ship）可以把作为载荷的船只或水面漂浮构造物驮载出海并运输至目的地；与自备有大型卸载设备，可以在缺乏吊车之类卸载设备的港口作业的重吊船（heavy project vessel）。

一般说来，单件50吨以上，或长、宽、高超过30公尺的货物称为重大件货物。而单件超过1000吨，或长、宽、高超过100公尺的货物称为「特重大件货物」。这类特重大件的运输没有标准的做法，需要设计专门的运输方案，虽然运输时风险高，但承运人也有机会获得丰厚的利润。

derrick. After World War II, DDG Hansa became the world's largest heavy lift shipping company. In terms of lifting capacity it reached its peak in 1978 with refitting the Japanese built bulk carrier MV Trifels with two 320 t (315 long tons; 353 short tons) Stülcken derricks. Shortly after that, in 1980, DDG went bankrupt. With that, only the Dutch shipping companies Jumbo, BigLift Shipping (until 2001 named Mammoet Shipping) and SAL Heavy lift were left as heavy lift shipping specialists.