Well, this is a good idea (For servers), but it needs a mechanism that runs in two tracks, and in a way that GUARANTEES that there is a boat at each end.
I have a prototype that works in regards to triggering the other rail to launch without causing a retrigger on outbound travel, but keeps screwing up. For some reason, one of the two starter pistons wants to fire slightly earlier than the other one, even though the activation signal is identical in regards to delay and whatnot (signal doesn't split until reaching the pistons)
Should probably screenshot
EDIT: Also, I've heard it doesn't work in 1.2 for some reason