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Jun 7, 2005
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Rivtow Hercules
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Issue:
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May / June 2005
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Author:
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KE Heaton & Capt. Don Rose
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The Rivtow Hercules is a self-loading, self-dumping log barge. This type of vessel is unique to the west coast of Canada. This style of barge is very efficient in their job of raw log transportation in exposed waters. These vessels have evolved through many years of trial and error. Moving logs started with old ship hulks that were loaded and unloaded from an external facility. Later came the self-dumping flat deck barge that was loaded from an external facility and dumped in a similar manner to how they are now. Then came the modern self-loading, self-dumping barge like the Rivtow Hercules.
The Rivtow Hercules is fitted with two cranes, with one at either end of the deck. She measures approximately 122 metres long, with a breadth of nearly 29 metres and a depth of 8 metres. She has a carrying capacity of over 15,000 metric tonnes. An average round trip for the Rivtow Hercules aits tug Capt. Bob can range anywhere from 200 to 2500 miles. The Capt Bob has an average speed without a tow of nearly 13 knots. The Hercules can move up to 11 knots empty. Towing the barge loaded the two move approximately 9 knots per hour.
On a typical trip, the empty Hercules will arrive at a logging camp or storage facility with the Rivtow tugboat Capt. Bob. The crew at the storage facility or camp will meet them with a small tug that assists the Capt. Bob with securing the barge for loading. Also meeting the barge at the location to load the barge will be 4 crane operators.
Once the barge is secured to the storage facility, two dozer boats are then unloaded from the barge to assist. These small tugboats, approximately 5 metres long, launched from the aft of the barge, are used to place the logs alongside the Hercules for the two cranes to pick up and place the on the deck of the barge.
To prepare the barge for loading, the crane operators must strip the ballast and tipping tanks of any water and service the cranes and grapples. When loading the barge, crane operators will spell each other off in 3-hour shifts as loading can easily take six hours and more when all the logs are at one location.
The barge must be loaded in a certain way so that it will have proper trim and stability for transit on open waters. The barge must remain stable on transportation but the logs must also come off the barge in the correct way at its destination. Crane operators must have a great deal of expertise to precisely load a barge with logs. When loading is complete, a stability test is done. The dozer boats are then loaded back on to the stern of the barge and the cranes are secured for the voyage to either another pick-up location or its final destination.
During transit a wide variety of weather conditions can occur, vastly lengthening the trip. The West Coast of BC has many narrow passages and channels that may have to be navigated in various weather conditions. There are numerous narrow channels with severe tidal conditions that can only be navigated at low tide, with the tides at their minimum velocity. The job of timing the move through these channels lies with the tug crews. Moving in open waters in bad weather conditions also poses many problems and the crew may have to steer along various courses to keep the barge from losing its load.
Upon arrival to its destination, a small tug comes alongside the Capt Bob to pick up a Mate and a Seaman and take them back to the barge. The small barge will get into place and put its towline on the barges’ stern to help hold her in place as the pre-flooding and dumping procedures take place. The crew on the barge services the generating machinery and makes sure the cranes are locked into place. With everything ready to go, a sea chest is opened along with several valves to pre-flood the ballast and tipping tanks for tipping the load off the barge.
As the dumping starts, ballast water is transferred from the starboard to the port side of the barge since the Hercules dumps on her port side. It is common that the barge does not dump after all the ballast water is transferred, so the sea chest is opened to allow more water into the tipping tanks. With the sea chest opened, the barge will continue to heal, generally at an angle of 26-30 degrees.
As the barge dumps, it actually moves quickly from under the load. The load itself does not move until the barge has separated from under the load. The barge moves sideways from under the load at a rapidly increasing rate of speed for a significant distance away from the load. At this time the small tug disconnects itself from the stern of the barge. The towing tug slips out its winch line to prevent it from being pulled over by the force of the moving barge. When the barge has settled down from her drop, (It takes the Hercules approximately an hour to level off) the Mate and Seaman close up the barge, leaving the sea chest and tipping tank valves open to allow gravity to drain the water. The assist tug will then return the workers to the Capt Bob and another trip to load logs will begin.
Written By KE Heaton
with original material supplied by Capt. Don Rose
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