Heats begin Friday morning, with finals in 31 events set for Saturday afternoon.
On the boys' side, St. Joseph's Prep is coming off a strong showing in the Philadelphia city championships on May 5. The Hawks won the lightweight eight and the varsity eight.
St. Augustine Prep finished second, and La Salle was third in both races.
"We're tickled pink," St. Joseph's Prep coach Jim Glavin said of the team's performance this season. "We only had one rower back from last year in the lightweight eight, and one rower back in the heavyweight eight."
Glavin said the "speed is from the south" this year in the varsity eight competition, noting that two boats from Washington - Gonzaga and St. Albans - as well as a squad from Winter Park (Fla.) will be strong contenders in the final race of the regatta.
"That is going to be a very fast race," Glavin said.
Another race to watch will be the boys' senior quad in a renewal of a fierce rivalry between Roman Catholic and Malvern Prep, with Conestoga in the mix.
Roman won the race in the city championships, but Malvern came back to capture the event in the Mid-Atlantics last weekend, with Conestoga edging Roman for second.
Holy Spirit managed a rare quadruple in the city championships. The Spartans won the junior-varsity eight, lightweight eight, second eight, and varsity eight.
"That was amazing," said Lauren Turner, the only senior in Holy Spirit's varsity eight. "All the boats are doing so well. We're trying to keep it going at Stotesbury."
The Spartans' varsity eight crew featured Turner along with bow Michelle Smith, Danielle Larotonda, Tara Puhalski, Amanda Reale, Samantha Stoll, Christine Wojciechowicz, stroke Lauren Slattery, and coxswain Claire McLenna.
Welsh said the youth of the varsity eight, which has three sophomores and five juniors along with Turner, was the reason for his diminished expectations at the start of the season.
"But these girls have worked so hard," Welsh said. "It's been a good surprise."
Holy Spirit won the varsity eight in the city championships by nearly five seconds, but rivals Merion Mercy, Bishop Eustace, Radnor, and Mount St. Joseph were separated by fewer than two seconds, and any of those boats could take that event.
The girls' varsity eight race also is expected to feature a strong boat from James Madison (Va.) High School.
Turner said the Spartans have their sights set on a good showing at Stotesbury.
"To us, Stotesbury is just as important as the nationals," Turner said. "It's such a huge event, with so much history. You see people from all over the country.
"To win Stotesbury would be a huge dream."
Contact Phil Anastasia at email@example.com. Follow @PhilAnastasia on Twitter. Read his blog, "Jersey Side Sports," at www.inquirer.com/