I suppose the writers really had to kill the guy who was on the boat and whoever talked to him. He was about to reveal Peggy was the one who attacked him with Jarvis' help and would have blown the operation wide open. I still think someone is going to catch on that Peggy's up to something, but I'm not sure to what extent. With Krzeminski and the muscle-guy out of the way, nobody will catch on right away, but it's only a matter of time. Somebody will grow suspicious or assign Peggy a task and realize she's not completing it because of something else. It's also possible they could find her prints on that muscle-contractor weapon she used. Then again, they didn't find her prints at her own apartment, so they might just be inept.
So the name of the boat was the SS Heartbreak and it had that symbol on it with the heart and some rope through it. There's obviously some sort of Leviathan connection to the boat, if that's indeed what that symbol was referring to. There were two hearts with lines through them in Peggy's book of symbols, but neither of them had a squiggly line through it. There might have been more heart symbols on the next page, but Peggy didn't get that far before the guy at the window interrupted. At least she noticed that the symbol was on the boat as well.
