Junior point guard Matt Farrell chipped in a career-high 13 points for the Irish (2-0), who took control early with a 15-2 run and led by 31 at halftime.
"We were very ready to go," said Notre Dame coach Mike Brey. "We shot it great because we passed it even better than we shot it."
Steve Vasturia also finished with 13 points as six Irish players scored in double digits, and they finished with 23 assists.
"That just shows we're sharing the ball and playing together," Beachem said. "That's our number one key to success, offensively."
After hitting just 3 of 16 3-point tries in their opening win over Bryant, the Irish knocked down 10 in the first half alone.
Matej Kavas scored 11 to pace Seattle (1-2). Redhawks leading scorer Brendan Westendorf, who came in averaging 19.5 points, did not score after missing all eight of his field-goal attempts, including seven from 3-point range.
He wasn't the only Redhawk who struggled as Seattle shot just 29 percent while committing 21 turnovers.
"Bottom line is, we were manhandled," said Seattle coach Cameron Dollar. "We didn't have the competitive spirit we normally have."
After being outrebounded by Bryant last Saturday, Notre Dame edged Seattle on the boards, 40-33, with Colson's eight leading the way.
After looking to pass first rather shoot in Notre Dame's first game, Farrell fired away from deep and hit three 3-pointers, while still managing to dish out four assists.
"I love getting other people involved, that's something I've always done, but if I get an open shot, I've got to take it," Farrell said. "That's something the coaching staff's been on me a lot. They want me to be more aggressive."
HE SAID IT
Brey: "One of the officials grabbed me at the end and said, 'Man, you've got a great vibe. Your guys really like playing together.' And that's quite a compliment. You can imagine how many different teams and vibes he's around in heated atmospheres, and I let our guys know that."
Seattle: The Redhawks, who play all five of their Legends Classic contests on the road, faced Notre Dame for the first time. After playing Colorado tough in a 12-point loss in Boulder last week, this one got away from the Redhawks, who trailed by 20 with 6:25 still to play in the first half.
Notre Dame: Unselfish offense by the Irish continued to impress Wednesday night, as the Irish are averaging 90.5 points after two games.
Seattle: Meets Louisiana-Monroe on Monday in the Legends Classic at Eastern Washington University in Cheney, Washington.
Notre Dame: Host to Loyola (Maryland) on Friday, its third straight home game to open the season before facing Colorado in the Legends Classic at Barclays Center in Brooklyn