We were sailing and racing in a fleet of boats, heading 180, approx wind direction 270, under spinnaker. With less than 5kts wind we were making approx 2kts across the tide. A sailing barge was under motor heading 090 with the current. It became apparent to us that we were on collision course, but, with the boats approx 150m apart and only a very small change of course to port required for the barge to pass under our stern we assumed we could hold our course. As the barge closed to approximately 100m, they seemed to be taking no action, so we hailed them.
After a few hails we saw a person who had been scrubbing the deck amidships straighten up look forward, drop his deck brush and run back to the helm.
Even at this stage, the boats were still 75m-100m apart. We were still unconcerned as we would nearly pass clear ahead and that the helmsman would make a small turn to port and still pass clear of our stern with ease. However, for whatever reason he slammed the helm over and turned to starboard, right onto a full collision course. The large heavy vessel managed to turn to a heading of 150-160 degrees by the time it collided with us, but I suspect its direction of travel was more like 120. With almost no boat speed we could take almost no avoiding action.
Thankfully no major damage or injuries were incurred as our vessel is light and we were able to fend off manually to keep the hulls from major impact.
Lessons Learned: The potential here for a major incident is considerable. It was a busy afternoon, with the area full of pleasure craft. The barge was under engine at about 6 knots without helmsman, or watch keeper keeping a suitable lookout.
It should go without saying, but from this report it appears to need repeating, that the keeping of a proper lookout is a prime responsibility. In slightly different circumstances, this minor bump could have been a major collision, with the potential for injury and legal action.
In addition to hailing, the use of an air-horn by the yacht may have helped attract attention on the barge a few valuable seconds earlier.