M&M...
You have a fine and practical idea for this contraption...dock repair. Of course, it would be best for crib docks, but it could also solve myriad issues with locating moorings (see Winn Diver's thread about losing some cutters in cruddy visibility last season), retreiving lost items, etc. Plus, we wouldn't have to deal with these darn wetsuits, which automagically seem to shrink over the winter months.