Hi, Sheila!
The only restriction presently publicized about the AquaDuck on the Disney Dream is that of height.
The minimum height to ride is 48", and that person must be accompanied by someone over 54" tall.
Passengers over 54" may ride unaccompanied.
Per the
official Web site:
"It was designed for adults and children at least 42" or taller. Single riders must be at least 54" or taller. Children under 7 must ride with someone 14 years of age or older, provided the child is at least 42" tall. "
The tube itself is 52" in diameter.
If someone in your traveling party has any concerns, the Cast Member working the ride will be happy to address them for you.
Bon voyage!
See you later, celebrator,
-Deborah B.