As of today, boats are now blacklisted items.
Many have you may have noticed there are times when the SMP server has frozen and times-out any login attempts. This is due to the server maxing out the CPU to 100% and therefore the entire server freezes. A number of us have reason to believe this is being caused by boats - which 90% of servers actually have banned for the exact same reason.
We will be performing extensive testing to determine the source of the CPU issue. Stay tuned.
Well! There goes my plan for a water park! :’(
You know, I noticed the greatest lag when I was sailing. you may be right about the boat issue. I wonder why it causes such trouble?
It appears to be just poor coding by Notch in SMP. Not sure why he still hasn’t fixed it since this issue has been around since the introduction of boats in the first place 
maybe cause he has bigger fish to fry? ahhhh, water puns =], but yea, i find that whilst minecarts seem to run ‘fairly’ smoothly on smp servers, boats have always had trouble syncing rightly and cause major cpu spikes, but where a boat can go, so can minetracks above it =]
Oh, please don’t tell me you’re going to ban minecarts too… D:
Yotsuba! Anyways, I don’t mind.
Minecarts don’t appear to be as much of an issue as boats are. Unlike minecarts, boats just leak like crazy and lag down the entire server.