You might also wish to read the topic below which (further down in the topic) goes into the differences for these types of micro/mini systems when used for Dam inspection.
http://www.rovworld.com/ftopic-2383-days0-orderasc-mini+rov-0.html
In most instances I would suggest that these micro/mini ROV units be used for inshore and limited access areas. In broad terms they are not offshore vehicles.