So the exact text on Arvel's card says:
"
If you would fail a
[boost]
action by overlapping another ship, resolve it as though you were partially executing a maneuver instead."
If you fail your boost because the template overlapped an obstacle, then you don't get to move. If Arvel fails by bumping, then he partially executes the maneuver.
What happens if you overlap both another ship and an obstacle in the same boost?
I can think of four arguable cases:
1 - The action fails because you check to see whether the ship would overlap or move through the obstacle BEFORE checking the ships final position. So you will always stay still for a failed boost.
2 - You check to see whether Arvels movement path would touch the obstacle or the other ship first. If he hit the ship first then it fails by overlapping another ship and you can execute it as a partial maneucer. If it hit the rock first, then it fails by the rock and Arvel's ability doesn't trigger.
3 - Both fails trigger at the same time, and you may choose which order to resolve them. So you get the choice of wether it fails from the rock and you stay still, or if it fails from the bump and you partially execute the maneuver.
4 - Both fails trigger at the same time, but since you satisfied the criteria or Arvel's ability, then you must use the ability "execute it as though you were partially executing a maneuver instead."
The TO in my tournament ruled for option 2. I would personally lean towards option 4, but since it is an abstract scenerio It was a fair call.
I now submit it to the FFG gods to make an appropriate FAQ.
And sorry if this has already been asked.