According to the faq:
Q: Are hero abilities and skills applied to attacks made
with cannons?
A: Yes.
And Tobin skill is:
When Tobin makes a successful attack, add the distance to his target to his damage.
So, if I understand it, if he attacks with a cannon that has +9 range, he should add +9 to damage if the target is separated nine spaces. WOW!!!!???