The “It’s a Small World After All” ride at Disneyland will be shut down for a rehab. One of the problems is that the boats originally from the New York World’s Fair in 1964-65 can not handle the 200 pound adults . The new boats will have a deeper flume and be more buoyant.
from : http://www.miceage.com/allutz/al100907c.htm
Quite simply, the boats weren’t designed to handle multiple adults weighing more than 200 pounds, and they now routinely bottom out in the shallow flume and get stuck. The Imagineers who designed the unique flume ride system for the World’s Fair assumed that adult men would average 175 pounds, and adult women would average 135 pounds. Needless to say, those 1960’s statistics are hopelessly out of date in today’s world. This same issue creates similar problems on the drops at Pirates of the Caribbean, or even on the older dark rides like Pinocchio or Alice In Wonderland as the more heavily loaded cars try to keep up their pace throughout the ride. But at it’s a small world, the weight related problems happen more frequently.