Ok, so here is my American Bumper Cars Fleet for the Bumper Cars Fleet Challenge. I've got a fairly well balanced pure American fleet with three ships; each having different abilities that help with ramming and boarding.
The first ship is the surprisingly powerful USS Maryland. When it is pinned, it eliminates a mast and crew. It has a captain to fire two 2-cannons, then roll for the ram, then have a chance to board and eliminate another crew. So, if it attacks first it has a good chance of eliminating four masts and two crew, ouch!. I would use this as my main attack ship, it can hold its own against pretty much any size ship. If it looses it masts it can use the oarsman to continue ramming to do major damage. If it is killed then it goes back to my HI (thanks to Ralph David) and in two turns is fully repaired.
The second ship is the Double Catamaran, Speedy Return. This really is an awesome ship and pretty much made for this type of challenge. Catamarans can't be rammed but can ram, can't be pinned and have extra hulls for added protection. I've made this ship my flex ship, it has some cargo room to gather gold (and use its treasure trading ability with) but it is also able to attack with a captain and canceler. This ship would also do well at taking out submarines in this challenge, it could possibly switch the cargo master for the Burr's helmsman if it needed extra speed to run a sub down. This ship would probably be teamed up with one of the other two ships depending on what it is up against and the layout of the ocean. Or get gold first, then go on the offensive.
The third ship is the USS Aaron Burr and it is the main gold runner in the fleet. It has four free cargo spaces with the cargo master and if it dumps the explorer it could have five. This ships ability would allow it to harass some smaller ships that maybe got to a wild island right before this ship arrived and cleared the gold. The ability should probably only be used on one and two masted ships. It also has decent 2-cannons if the ship it rams has a mast or two left and decides to stay and fight.
Both Unique Treasures have to do with ramming or boarding and benefit players looking for gold (like my fleet). Thompson's Island is my fort since I'm doing a pure American fleet and that is the only option.