Getting abroad with dogs.

We're hoping to tour abroad next year with our two Irish Setters. I've never towed abroad before but I'm OK with all the logistics once we get there. My concern is how the dogs will react to the journey. They're OK in the car when they can see where they're going but I don't think any ferry companies will allow you to stay with them during the journey (we're looking at a shoert crossing). Any advice?