Changes

===Semisubmersibles===

===Semisubmersibles===

''Semisubmersibles'' (also called ''semi's'') are usually anchored in place ([[:file:offshore-rigs_fig3.png|Figure 3]]). Although a few semi's are self-propelled, most require towing. Because floaters are subject to wave motion, their drilling apparatus is located in the center where wave motion is minimal. Semi's are flooded to a drilling draft where the lower pontoons are below the active wave base, thereby stabilizing the motion.

''Semisubmersibles'' (also called ''semis'') are usually anchored in place ([[:file:offshore-rigs_fig3.png|Figure 3]]). Although a few semis are self-propelled, most require towing. Because floaters are subject to wave motion, their drilling apparatus is located in the center where wave motion is minimal. Semis are flooded to a drilling draft where the lower pontoons are below the active wave base, thereby stabilizing the motion.

===Drill ships===

===Drill ships===