When you're hot, your .198-hitting catcher slaps a game-winning two-run homer into the left field seats. So it goes for the Baltimore Orioles.

Rick Dempsey, who began the night in a two-for-26 slump, broke up a tie game with a towering sixth-inning homer and Mike Boddicker pitched a 10-hitter as the Orioles won again, beating the Seattle Mariners, 6-3, before 11,614 at the Kingdome tonight.

The victory was the fifth straight for the 25-16 Orioles and their 13th in 15 games as they remain in third place in the American League East, 2 1/2 games behind the first-place Boston Red Sox.

This was a game the Orioles didn't necessarily figure to win. Not only were they facing Seattle's Mike Moore (2-6), who dominated them in 1985, but they came into the game with a bullpen that was worn down thanks to a starting staff that had finished only one of its last 21 assignments.

Nonetheless, they kicked Moore around for 10 hits and five runs in six-plus innings, getting a game-tying two-run homer from Fred Lynn in the fifth and the game-winner from Dempsey in the sixth.

"Dempsey is our secret weapon," Orioles Manager Earl Weaver said, tongue deep in cheek. "You keep him quiet for a while, then you say, 'Sic 'em,' and there he is. See, he could probably hit .300 if we let him, but we like to have him laying there in the weeds."

Which is where Dempsey has been, admittedly in one of the worst slumps of his 13-year career. In fact, Weaver hadn't even planned to play him tonight, but when he saw that Dempsey had one of the Orioles' top averages off Moore -- .267 with a homer -- he went with him.

The Orioles also got a gutty nine-inning, 157-pitch performance from Boddicker (5-1), who allowed three runs and six hits in the first two innings, then settled down to shut out the Mariners on four hits the final seven.

In pitching his second complete game of the season and first since April 14, he allowed nine hits in the first five innings, then retired 15 of the final 17 Mariners, including 11 in a row at one point.

"I battled through the fourth and fifth innings," Boddicker said. "I didn't get a 1-2-3 inning until the sixth, and that was a big one. It was a struggle, but Earl had told me I had to be the long man. I knew if I got into trouble and got rocked a little, I'd have to get myself out. The bullpen needed a night off.

"They were hitting my change-up early and I said, 'Enough of this.' You can hit the change if you know it's coming, but you can't hit the curve if you know it's coming. So I gave 'em curves."

Trailing by 3-1 after four, the Orioles tied it on Lynn's homer, his second hit of the game and one that continued his amazing hot streak. In the Orioles' last five games, he has gone 11 for 19 with three homers and nine RBI and raised his average from .291 to .328, which places him among the league leaders.

But perhaps the Orioles' best news was from Dempsey, who entered the game in one of the worst slumps of his career.

A night earlier, he had struck out three times before being pulled for a pinch hitter, and when he came to bat with runners on first and second in the second inning tonight, Weaver had him lay down a sacrifice bunt.

He was allowed to swing away the rest of the evening, and that he did. In the fifth, he singled to left and scored in front of Lynn's homer. Then in the sixth, he came to the plate after Mike Young had doubled with two outs and hit his fifth homer of the season.

"I didn't even deserve to play, to tell you the truth," Dempsey said. "I've been completely messed up, but I finally hung in there on a breaking ball. That's the first one of those I've hit in a while. Maybe this'll get me going."

The Orioles got Boddicker an insurance run in the ninth when Jim Dwyer doubled and Eddie Murray got his third single of the game.

Six of the first eight Orioles reached base against Moore, but after two innings, Baltimore still trailed, 3-1.

In the first inning, second baseman Alan Wiggins drew a leadoff walk but was erased on Lee Lacy's double-play ball. Lynn and Murray followed with singles and Moore walked Cal Ripken to load the bases. But Larry Sheets bounced out to first baseman Alvin Davis to end the inning without a run.

After the Mariners scored two runs in the bottom of the first, Baltimore cut it to 2-1 in the top of the second. The Mariners made it 3-1 in the bottom of the second before Boddicker settled down, setting the stage for Lynn's game-tying homer in the fifth and Dempsey's game-winner in the sixth.

Reliever Tippy Martinez pitched three shutout innings in his second rehabilitation assignment for Class AAA Rochester today.

Martinez allowed two hits, walked two and struck out two, and General Manager Hank Peters said he'd talk to the Rochester staff before deciding if Martinez is ready to return to the major league roster.

When that happens, the Orioles must make a roster move, and indications are that a non-pitcher will be dropped as the pitching staff is expanded to 10. Backup catcher John Stefero (.192) appears the most likely to go.