| Abbreviation | Definition |
|---|---|
| MBY | Motor Boat Yachting |
| MCBC | Mansfield College Boat Club |
| MCOB | Master Chief Of the Boat |
| MCSC | Milwaukee Community Sailing Center |
| MGB | Motor Gun Boat |
| MISE | Maersk International Shipping Education |
| MKSC | Milton Keynes Sailing Club |
| MLDB | Major League Dragon Boat |
| MNSC | Middle Nene Sailing Club |
| MOB | Man Overboard Boat |
| MRBC | Missouri River Boat Club |
| MRBC | Muskegon River Boat Club |
| MS | Motor Ship |
| MSC | Manchester Ship Canal |
| MSSC | Muscle Shoals Sailing Club |
| MUBC | Melbourne University Boat Club |
| MV | Motor Vessel |
| NASS | Naval Academy Sailing Squadron |
| NBSA | New Brunswick Sailing Association |
| NBSA | Niantic Bay Sailing Academy |