Talk:Semi-submersible

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[edit] Definition of semisubmersible

In shipping industry I think a semi-submersible is a crane ship or a he drill rig that is described in the article. I do not think that the "drydockships" are called semi-submersible. Jeff 18:16, 14 February 2007 (UTC)

I know bugger all about the shipping industry, but Dry_dock#Floating_Drydock describes what I understand to be a semi-submersible. RupertMillard (Talk) 20:45, 14 February 2007 (UTC)

English is not my native language that is why I may know the meaning of the word semi submersible better than somebody with a English native background. A semi submersible is not the same as something that is sometimes submersible and sometimes not. Semi-submersible is an international word, that is used in all countries in the world under this name. A semisubmersible or semi sub is a floating object that gets its basic buoyance from under water floaters. The deck is built above water and the connection between floaters and deck is with pillars with relatively small buoyance. This gives the advantages that the movement of the waves has relatively small influence on the movement of the vessel. On the other side, a change of the center of gravity of the floater will tilt the vessel immediately. This must be corrected by ballastwater, in fact in the same way as on board of a submarine. The design of a semi-sub is an optimalisation between dependance of the heave and the stability. This means that a floating drydock or a heavy lift ship etc. are not called semi-sub as far as I know. Jeff 10:29, 18 February 2007 (UTC)

While your note about the definition of semi-submersible is interesting, in the maritime industry, "semi-submersible" is used interchangeably for "heavy lift" ship (whether or not they have drydock type wingwalls). The term used in the US Navy is "Flo/Flo", for float-on/float-off.

The only distinction that I am aware of is that some ships with heavy-lift crane capacity (300 tons +) are called heavy lift ships as well. Jay Standring 15 August 2007