They had to survive a ferocious comeback by the Ospreys, who at least prevented the Blues scoring a fourth try and picked up a losing bonus point of their own.
Wales centre, Shanklin said: “That was a massive game for us and it was important to start the Christmas campaign with a win.
“We knew when we scored the points early on that they were going to come back at us but we didn’t expect them to come back so close. It was a really physical match, the way local derbies always are, so we have to look after ourselves over this period.”