Lake Services is currently using the system for dredging small
channels in Baltimore County, near Baltimore, MD. "These
channels sometimes go out in open water a mile or more away from
any landmark or device that we could use as a positioning
device," says Firth. The operator simply plots the limits of the
channel into the system. "If the channel is, say, 50 ft. wide,
we plot both sides and each of the turns. Just like a surveyor,
we plot all of this information into the device and it puts us
on the map," Firth points out. "The channel may be several
thousand feet long with several turns in it. And as we work down
through there, we can see where we've been and clearly define
where we are." Swimming into place Using the customized GPS as a
guide, the excavator operator is able to accurately maneuver the
barge from one position to the next. This is achieved via a
specially adapted barge spud operating system linked with the
excavator hydraulics. "A hydraulic excavator normally uses six
circuits, but they almost