score:1
In google maps you can see the ferry routes as a dotted line in the water. In your map you can see that the only route by ferry is from Tobermory, and is really far...
I couldnΒ΄t find any other ferry that gogle does not know so I am sorry but I would say that there are no other available options, except for land travel.
One thing to try is to go to some harbour and look for a ship that can take a car, ask the owner if he would like to do this trip and for how much. Anyways you have to be so lucky for this and even that maybe it will take the same time or more as with car or be really expensive