Extra actions are for pansies - here's a fleet that does without them quite effectively! This build nets you the three best treasure runners in the game, a fantastic gunship, and protection from events via Favor of the Gods.
With this much treasure running potential, the 'burden of attack' will almost certainly be on your opponent, forcing him to send in his gunships. They will first have to deal with Franklin, which can stop an enemy gunship in her tracks and return fire with 3x 1 rank cannon and a 1 rank firepot attack.
The canceler is such an amazingly versatile crew since it not only functions as a powerful defensive weapon but also provides insurance against submarines, seamonsters, L/S range invulnerable ships, and other unwelcome surprises.
I agree that extra actions are a cheap way to try and win the game. Still, a canceler might not be enough alone to stop them. They can simply use another of their many actions to blow your ship away. The trick would be to find a way to negate their gunfire AND have a canceler so that they cannot cancel back. Still, I like the fleet you have created, it looks like a lot of fun to play.
This is a pure power fleet... the best, cheapest treasure runners in the game with the Franklin, one of the cheapest high-power gunships in the game. Going up against this fleet would be very tough.
I'm not sure how it would do against a fleet with one or more SAC captains though. You have to be within S to cancel the SAC ability, and more often than not you use that SAC ability at least L+S+L+S away, pouncing in with a gunship that was staying out of cannon-range to start with. Likewise, a treasure runner using SAC would never get near the Franklin.
I like the "swiss army knife" utility of a canceller, though. They are an excellent trump card with an incredibly wide variety of uses. I was disappointed, for example, with the anti-submarine crew that showed up in Frozen North. For 5 points you can shoot at submerged ships. For the SAME points, you can just bring a canceller instead, and cancel the keyword that allows them to submerge, and also cancel *so much more*, not only on your turn but on your opponent's turn. The anti-sub ability should have been 3 points at most.
Look at the base speed of your opponent's gunship(s) and add on an S for a helmsman (or more if its a ship like Christobal) and an S or so for cannon range and stay that far away from your opponent. Then they'll have to use an extra action just to move into range, allowing you to cancel their captain and their entire attack. If you get hit by a triple action gunship though, you're in serious trouble. Like I said, this build has such great treasure running potential that you practically force your enemy to send his gunships after you (unless he's playing a swarm fleet or some related variant).
I have had experience with cancellers, and when they swing in, cancel the captain ability. If they have triple actions or more (usually not) you'd better figure on weathering some gunfire. Otherwise if you stop the Captain, all they can do is ram you.
But be careful, if they get wise to it, they'll just pummel you from L range.
Since 45 point fleets usually only allow for one main gunship, your opponent shouldn't have any time to 'get wise.' One volley from Franklin with a Firepot usually does the job.