Dozens of Shepherd's friends, including classmates from Lincoln Park High School, are expected at the Columbia Yacht Club for the memorial.
Shepherd was on his grandparents' boat with three friends early Friday morning. They decided to go swimming and the boat drifted away.
"They were very, very close to the young man, their grandson, and it just tears your heart out, there's nothing you can say," said Pauline Stubbes, family friend.
"I couldn't believe it. I don't know what to say. It's like still surreal," said Frankeshia Jackson, high school friend.
Two female friends survived and were rescued by a fishing boat.
The search continues for another friend, Christopher Gary, who is still missing.