When built without guide tracks, guests on the boat hire are free to roam wherever they like on the body of water. Most of the time the boats will take the most direct route back to the start of the station platform, so don't expect them to go up and down a river, for example. Sometimes they can get stuck within structures and scenery located on the water. The best way to prevent this from happening is to place the in-water fountains to block off potentially hazardous areas. If the guests are already stuck, the ride can be 'reset' by selecting 'close' twice in the ride window; if guests continually get stuck, it may be wise to edit the ride to eliminate problem areas.
When incomplete guide tracks are built, boats can get congested as 2 or more boats try to go into the guide track opening, causing all boats to be stuck.
In RollerCoaster Tycoon 3, in order to have a smaller dock you can have 'track' pieces at the end of the dock (the opposite side to the front, where peeps would climb aboard) to allow for more 'cars' or selected vehicles.
