From the TSB report
History of the Voyage
The North Arm Venture departed Vancouver, British Columbia, on 17 July 2009, bound for a number of locations. On 18 July 2009, the North Arm Venture left Toba Inlet, British Columbia, at 2100. 3 The tug, with a crew of four,wastowing the barge North Arm Express, heading for Sechelt Inlet, British Columbia. Cargo on board the North Arm Express included 370 156 litres of diesel fuel and gasoline in bulk, 5 empty bulk cement carriers and 3 trucks on deck.
As travelling time from Toba Inlet would have seen the tug arrive about an hour after slack water, the decision was made to "run slow" to arrive at Sechelt Rapids at the following slack water in order to transit at low tide slack water, predicted at 1254 on July 19.
The master, mate, and crew were working a watch system of six hours on/six hours off. The master and deckhand No. 1 worked from 0600 to 1200 and 1800 to 2400, whereas the mate and deckhand No. 2 worked from 0000 to 0600 and again from 1200 to 1800. There were no indications that fatigue was a factor.
On July 19 at 0600, the master came on watch when the tug was abeam Scotch Fir Point at the entrance to Jervis Inlet, approximately 16 miles from Sechelt Rapids. The tug and tow proceeded at slow speed, planning to arrive at the Sechelt Rapids at low tide slack water. At 1200, the tug and tow were 2.8 miles from Sechelt Rapids, abeam Egmont Point, when the master handed over the watch to the mate. The master and deckhand No. 1 subsequently went down to the galley for lunch, after which deckhand No. 1 went forward to the forecastle to rest. 4
At 1215, the master returned to the wheelhouse top to provide the mate with advice during the transit through the narrows.
At 1235, the tow line was shortened to approximately 19 m 5, including an 11 m bridle, to enhance manoeuvrability for the transit through the narrows.
At 1246, the master took over the helm and increased power to half ahead to proceed into the ebb current. The ebb current was still running, estimated at 1 to 2 knots, but the master noticed it was diminishing. As they approached the narrows the barge experienced a sheer to starboard. The master commenced his alteration to port, from a heading of 220º True (T) to a heading of approximately 136º T. The barge, however, did not follow through the turn and continued on its course. 6 To regain control of the tow, the master then sought to reposition his tug ahead of the barge by applying starboard helm. This manoeuvre was unsuccessful, and the barge overtook the tug.
Pulled starboard by the force from the towline, the tug girded on its starboard side (see Photo 2) and quickly capsized at approximately 1250 in position 49ºC 44.5’ N, 123ºC 54’ W.
Transportation Safety Board of Canada - Marine Investigation Report M09W0141