Projects

Rialto M. Christensen - An Explosive Combination

Grab Excavation System The Panama Canal Authority (PCA) has one of the heaviest, toughest dredgers in the world – and she’s now highly intelligent too, writes BERT VISSER

The PCA’s mechanical dipper dredger Rialto M. Christensen (RMC) was built in 1977 by the Japanese Hakodate Dock Company in the days when the Canal was still under US governance. Designed to replace several classic steam dipper dredgers, RMC is a diesel-electric, cable-operated vessel designed for what’s acknowledged to be some of the most difficult conditions to be found anywhere. Not only does she play a daily role in maintaining navigation channels, but even though the Canal celebrated its 90th year in 2004, there’re still several places where its banks have yet to reach their so-called ‘angle of repose.’ And from time to time landslides occur that create shoals consisting of a variety of material, including large, heavy rocks.

MAID OF ALL WORK
Besides the maintenance task, Rialto M. Christensen is also deployed for major capital dredging projects as part of PCA’s objective to increase the Canal’s transit capacity. In recent years these have included:

Widening the Gaillard (Culebra) Cut, and
Deepening the navigable channel through Gatun Lake.

It was at Gatun Lake on February 19, 2004 that RMC dredged 7,800 cubic yards (6,000m3) of muck and debris in a single eight-hour shift – breaking a record set by one of her steam-powered predecessors, Cascadas, in October 1916 when 7,700 cubic yards were dredged in one shift. That performance was achieved despite the rather old-fashioned way of monitoring the position of the dredger’s 15 cubic yard (11.5m3) bucket – marks on the stick. But today, as part of its permanent modernization programme to enhance the Canal’s efficiency and reliability, the PCA, has equipped Rialto M. Christensen with a modern software system from Dutch specialists Seatools to monitor and visualize the dredging process.

THE SOFTWARE
Seatools won the contract based on an adapted version of their DipMate package for backhoe and dipper dredgers – a member of the firm’s DredgeMate family of systems suited to various dredging functions, HopperMate, CutterMate and DrillMate amongst them. The standard DipMate package, designed for basic backhoe and dipperoperations, uses a 3D visualization engine linked to sensors for boom, stick, bucket, slew and tilt x/y. But the mechanically-operated Rialto M. Christensen’s configuration made it necessary to add a tool to monitor the distance of the bucket’s extension with respect to the dipper handle – achieved by mounting a distance measuring laser on the dipper handle. The PCA also required two further
features:

A crane rotation angle warning signal – the angle’s limited to 90 degrees when all engines are shut down automatically. To avoid this, a visual warning’s incorporated that signals the crew when the angle reaches 70 degrees.
A positional warning signal – due to the Canal’s limited width, especially in the Gaillard Cut, it’s vital the dredger stays within a limited area or she could constitute a hazard to passing ships or even be caught in their wake.

FINALLY...
To provide her dredgemaster with an optimal view of the dredging process under all circumstances, Rialto M. Christensen’s crane is equipped with two control cabins, one on either side. Which meant the DipMate visualization software had to display dual positions. Seatools coped with that too, creating the entire system in Holland before packing it off to Panama where it was installed aboard the dredger under the supervision of project engineer Lennert de Oude. Part of the deal including training 25 PCA employees to use DipMate, carried out with both classroom and practical exercises. And the system was handed over in late September last year. As I write, Rialto M. Christensen is working to the complete satisfaction of the PCA with its DipMate system improving her efficiency – who knows, maybe another production record will be set in the near future!

The origin of this story is DPC magazine February 2005

More info at www.dpcmagazine.com