This last March, while aboard the Mahalo ( @LeslieTroyer 's boat) we were sailing westerly across Rosario Strait on Port tack. A south bound commercial tug (no tow attached) was going to cross our bow. Visibility 10 miles in clear sky's. At 3 miles we could see that our paths would cross. AIS said the CPA (closest point of approach) would be less then .1 miles. Visually the bearing to the boat did not change. As we closed we called the boat using DSC. No response. We tried Channel 13 using the AIS listed boat name. No response. Still closing and no change in bearing, we tried hailing the boat on CH 16 using the boats name. No response. Now less than 1/2 mile we turned into the wind and let the A$$ carry on at 12 knots and a breaking wake wave. Other than that it was a beautiful day for a sail.