Do large semi-submersible crane vessels such as the SSCV Thialf propel themselves to work sites or are they carried on heavy-lift ships. I understand they have propulsion systems but the just seem so bulky, inefficient, and slow to move across oceans on their own.
Very large capacity crane vessels have propulsion machinery for manoeuvring when on station. The most modern designs of semi-submersible vessel use them to achieve 'dynamic positioning'. Older designs used the propulsion systems to assist when deploying the anchors in the correct pattern. The vessels are towed by tugs when making deep sea passages. First generation crane vessels had much smaller lifting capacities and were either constructed on conventional hulls or were converted from existing ships. These types were capable of making ocean passages using their own propelling machinery.
