control cabin and workshop cabin , a Launch and Recovery System ( LARS ), a high pressure unit ( HPU ) and an umbilical winch . This type of ROV normally operates at a depth of less than 500 metres and is normally fully electrically powered .
Work Class A common work class ROV in offshore operations is normally rated at less than a 100HP and can dive up to a depth of 1,500 metres . It can weigh up to five tons with a complete payload . The package may include two 20 foot shipping containers , one each for the control cabin and the workshop , which includes the HPU , LARS and an umbilical winch . This class of ROV is always equipped with manipulators on the port and starboard sides to work underwater . This type of ROV is normally hydraulically powered but electrically powered models are not uncommon . With an additional payload capability , this ROV can include add-on tooling packages such as inspection rollers , addon manipulators , an additional HPU , and add-on sensors such as a fibre optical multiplexer , etc . from the vessel due to the drag created by sea water on to the umbilical surface which may swing off the ROV and disturb the operation .
With new technological advancements , there are new ROV classes coming on the market . One of these is the Autonomous Underwater Vehicle ( AUV ). Nevertheless , the three classes mentioned above are still the most preferred and commonly used in the offshore industry .
Figure 5 : Typical ROV control panel in a control cabin .
PROJECT EXECUTION PLAN
Figure 4 : Heavy work class ROV system
Heavy Work Class This is similar to the work class ROV , but it has more power ( more than a 125HP ) and can dive deeper normally rated to a depth of 3,000 metres . This class is also equipped with a Top Hat Management System ( TMS ) which sits on top of the ROV during launching and is released from the ROV when the project depth is achieved . The TMS normally carries 500 metres of umbilical tethers . It can weigh up to 2.5 tons . The function is to act as a counterweight for the main umbilical tethers
Proper planning for every ROV task is essential to obtain a good track record for the ROV operator . To achieve this , long years of experience and training are essential for engineers who deal with ROV operations .
For an ROV to work flawlessly ( in an ideal practice ), the following people are required in a project team :
1 . An Operations Manager who oversees and manages the whole project including the team members .
2 . A Secretary / Admin Assistant who manages all HR activities including crew management and their logistics , personnel database , their Health , Safety and Environment ( HSE ) certificates and other personal requirement , etc .
3 . An Operations Engineer who manages everyday activities of the ROV offshore team , ROV mobilisation preparation and demobilisation , records all offshore reports , and responds to requests from the team .
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