| ACRONYM | FULL WORDING | COMMENT |
| IFO | Intermediate fuel-oil | Viscosity of such fuels is maximum 180 Cst or below (it is a mixture of HVF + GO) |
| IGS | Inert Gas System | |
| IHP | Indicated Horse Power | |
| IMO (ex IMCO) | International Maritime Organisation | Consultative body, branch of the United Nations, competent in matters relating to the safety at sea (f.i. the Solas Convention) |
| INC, INCL | Including, Included | |
| INCLOT | Including Overtime | Concerns the crew - is used when fixing a Time Charterparty |
| INCOTERMS | International rules for the Interpretation of Trade Terms | A publication of the International Chamber of Commerce, universally used |
| INFO | Information | |
| ISO | International Standardization Organisation | |
| IWL | Institute Warranty Limits or : Institute Warranties - Geographical and Chronogical provisions | Such limits indicate when / where vessels can trade with/without paying an extra insurance premium for navigational risk |
