On British Columbia’s rivers, tug captains learn to read tides and currentsAug 22, 2012 01:50 PM
The 45-foot, shallow-draft tugboat Katzie Pride is tied up at a Fraser River log sort in Coquitlam, British Columbia, ready to head up the Pitt River to pick up its next gravel barge.
Tugs have been towing aggregate-laden barges out of British Columbia’s Pitt River and on down the Fraser River since the days of wooden scows and steam-powered tugs. Since the earliest days the boats have had to contend with the railway bridge about three miles upstream from the Pitt’s confluence with the Fraser River.
Over the generations, skippers have learned a lot about the tides and river currents that challenged the old steam power and continue to challenge the modern diesel-powered tugs. This is not stuff that is taught in maritime training schools. It is knowledge that is learned by making the run with an experienced captain and finally by new captains feeling their way into the job.
Recently Capt. Tim Rogers ran the 45-foot tug Katzie Pride upriver, light boat, to pick up a loaded gravel barge at the Pitt River aggregate site a little over four miles upriver from the rail and highway bridges. The bridges are more than 20 miles from the Sand Heads, the official Fraser River mouth. Pitt Lake, a few miles farther upriver is one of the largest tidal lakes in North America. Rogers explained that the tidal effect varies greatly with the height of any individual tide and the volume of flow in the rivers. In other words, an ability to read the waters on any given tow is paramount.
Above: the barge loaded with aggregate slides smoothly through for a successful bridge transit.
When river people read the tide book they check the times for high and low water at Point Atkinson just outside Vancouver Harbour, nine miles north of the mouth of the Fraser. Depending on where they are, they add time to the book time to allow for the delay as the tide pushes upriver. The tide at the Pitt River rail bridge is about three hours later than at Point Atkinson. This will vary 15 to 30 minutes depending on variables like the season as the freshet can vary river currents and heights. Tides also vary ranging up to 14 feet vertical rise at Point Atkinson. Rogers explains that the whole business of tide and current on the Fraser and Pitt rivers is actually even more complex. “The heavier salt water comes into the river like a wedge under the fresh water so the river level may raise while the surface current is still flowing down.”
Katzie Pride arrived at the quarry on the Pitt at 1800. The 3,000-ton capacity barge that had been brought upriver the day before was now loaded with 2,500 tons of gravel. Deck hand Kyle Fraser climbed onto the barge with running lights and a tape measure. After measuring the freeboard on each of the barge’s four corners, he fitted the running lights into their slots on the barge while Rogers ran the boat around to the bow of the barge. Fraser reached down onto the boat’s deck with a pike pole to retrieve the 45-foot one-inch wire bridles from the tug’s stern. He dropped these over the barge’s bollards and jumped down onto the tug’s deck.
By 1820 Rogers was easing the barge off the pier. “This boat was built to operate on an inland lake and so it is built light and has a shallow draft so is easily pulled around by the barge,” Rogers explained as the bridles came tight and the little tug jerked and listed to port. At the same time the head of the barge swung out into the river and began its ponderous 180-degree turn to face downriver. With a loaded draft of about 13 feet, this is a lot of weight for the powerful little tug. Empty, the barge draws about two feet with a 16-foot air-draft. To aid in handling the light barge, Katzie Pride, like many Fraser tugs, is fitted with a “headache rack.” This is a heavy steel pipe that arches over the towing winch to protect the exhaust stacks and wheelhouse when the rake of the barge surges over the tug’s transom.
Rogers pushed the throttle forward so that the twin Cat engines put their total of 1,000 hp to strain on the bridles. Gradually the heavy barge fell into line behind the tug. “I like to think of the relation between the tug and barge as having a conversation,” Rogers had told me earlier. “The loudest or most persuasive has the power. The barge has power from size and weight. The tug has power from the engines.”
Soon the tug and barge resolved their conversation with the barge following dutifully behind with about 60 feet of tow wire between the tug’s winch and the bridles. The tide had turned to ebb at Point Atkinson but here, on the river, the current is still running up so that the tug is making only 2.6 knots against the flood current. By 1905 the bridge is in sight but still an hour away. At 1925 Rogers calls the bridge operator, “We’ll be there in about 35 minutes.”
The lead gives the bridge operator the opportunity to ask a train or the tug to slow if necessary to avoid any conflict when the swing span opens. Rogers has timed his approach well as the tug is still bucking a current. A barge loaded with 2,500 tons of gravel doesn’t stop easily. As he comes up to the gap in the bridge, Rogers moves to the controls on top of the wheelhouse where the visibility is best. A highway bridge, just up from the rail bridge, with an air-draft of about 40 feet is not a problem even though the water level can raise about eight feet on a high tide. He looks ahead at the rail-bridge gap and back at the corners of the barge. Rogers has made this passage many times, but this is not a time to relax his vigilance. “It is all in the approach,” he said. “Once you are there you are going.”
The tug, with the obedient tow, slides tidily between the bridge abutments and Rogers moves back down to the interior wheelhouse controls to enjoy the easy part of the tow and a spectacular sunset. The tow enters the Fraser River as darkness settles over the construction site of the huge new Port Mann Bridge where Rogers and Katzie Pride have done a lot of work as the construction crews like the shallow draft that lets the tug in close to the beach.
By the time the tow is in the Fraser at 2015 the flood current is slackening and the tug’s GPS is showing 3.5 knots. By 2135 the current has turned and is pushing the tow downriver at 6 knots. The tug is approaching the swing span of another rail bridge at New Westminster that opens regularly for taller barges, but this one will slide under the span so there is no need to have it open. Rogers asks Fraser to lower the mast to be sure that they clear the bridge.
With the pressure of the Pitt River bridge behind, it is time to recall the very similar gravel barge that hit the Queensborough rail bridge in June 2011 (PM #153). As we moved down the main arm of the Fraser we could see, off to starboard, the bridge at the entrance to the Fraser’s North Arm. In that instance the barge was off channel enough that the end of the swing span impaled itself in the gravel on the barge. Speculation about the cause is cautious. Was there confusion about which would be the lead and which would be the assist tug? Was the mate or the skipper on the wheel? Was there not enough experience or did a surfeit of experience cause a casual approach? Regardless of the actual cause, it will be discussed in the wheelhouses of Fraser River tugs as a cautionary tale of gravel and bridges for years to come.
If there is a lesson to be learned, it is summed up by Rogers’ philosophy of keeping the conversation between the tug and the barge going and never taking anything for granted.Edit Module