The sweep moves the Lancers to 23-6 overall, 20-4 PacWest, just one game in the loss column behind HPU for first place.
The Sea Warriors are now 17-5, 9-3, getting swept for the first time this year.
"This was a mental grind for our guys," said CBU Head Coach Gary Adcock. "They mirror us a lot in their offensive approach. They don't take any pitches off. I'm proud of the way the guys were able to grind through it and bounce back from yesterday."
Marnati was 4-for-4 with four RBIs in the opener, hitting a an RBI single to right in the fourth and then scoring on the same play when the ball trickled under Blake Amaral's legs and rolled all the way to wall. Then in the eighth inning with the Lancers trailing 4-3, he launched a bases-clearing double to left center against HPU closer Ed Trovato to give the Lancers a 6-4 lead.
He then went 4-for-5 with three runs and three RBIs in the nightcap.
"Matt's been a special player for two years for us, but what we've been seeing lately is growth," said Adcock. "He's become a great two-strike hitter and an early-count hitter, and today he proved that he's one of the better hitters in this league."
Marnati finished the series 9-for-17 with nine RBIs and six runs. In the eight games in Hawaii, he was 15-for-33 (.455) with 10 RBIs, nine runs, four stolen bases and three doubles.
HPU scored first, getting back-to-back singles from Rylan Morihara and Amaral in the third against Jon Bengard, but Marnati delivered in the fourth.
The Sea Warriors then took a 4-3 lead in the seventh with two more RBI singles. Bengard was tagged for four runs in 6.1 innings in a no-decision. It was first appearance this year that he didn't get the win.
Matt Daugherty tossed the final 2.1 innings to pick up the win, getting help from a 1-6-3 double play in the eighth, one of three Lancer double plays in the game.
Luke Esquerra, Daugherty and Blair Moore all hit consecutive singles in the eighth, and after Trovato entered and struck out Kevin Odom, Marnati, who struck out last night against Trovato, belted a double to the left centerfield wall, scoring all three runs.
Moore finished with three hits as he and Marnati combined for seven of the Lancers' nine hits.
In the nightcap, the Lancers jumped all over Sam Cooke, getting six hits and five runs in the first inning. Cooke only last one-third of an inning. The first five batters all singled, including Daugherty, who extended his hitting streak to 15 straight games.
Ryan Douglass delivered a two-RBI single to cap the scoring.
The Sea Warriors answered with three runs in the bottom of the first, getting an RBI triple from Amaral, and it seemed as if the game was headed for another tight affair.
However, Smith (6-1) regrouped and allowed just one more hit the rest of the way, a one-out infield single in the second. From there, he retired 16 in a row before a two-out walk in the seventh. He struck out seven.
"I probably sat a little too long in that first inning, because after that my velocity got back up to where it usually is," said Smith, who was working on just three days' rest. "All of my pitches were working. It was probably my best stuff. Most of pitching is mental. Physically, I wasn't feeling my best, so I just had to dig deep."
"I call that World Series rest," said Adcock, referring to Smith's outing. "He did everything we preach and teach our pitchers to do today, and he did it on World Series rest, bouncing back in three days. That was a great effort."
The Lancers then poured it on with a single run in the second and fourth and then seven runs in the fifth inning. Cole Bullard, who was 4-for-5, and Marnati both had back-to-back two-RBI single singles in the inning. Zach Esquerra delivered a two-RBI double.