Ugandan President Yoweri Museveni believes that the overload is causing the Saturday marine disaster on Lake Victoria, which has killed at least 30 people.
The ship designed to carry 50 people ended up with 120 passengers who drank, danced and listened to music. It sank only 150 m from the shore.
Many people on the boat are still missing.
This is the second accident on Lake Victoria in just two months. In September, more than 200 people died in the sinking of a ferry. The Nyerere, which sank off the Tanzanian shore, killing more than 40 people.