If all goes right on New Year's Eve, daredevils Robbie Maddison and Levi LaVallee will roar down the takeoff ramps on a motorcycle and snowmobile, respectively, fly over a 300-foot water gap, complete their record-setting jumps and toast their accomplishments.

The side-by-side jumps at Embarcadero Marina Park on San Diego Bay will be the latest in the "Red Bull: New Year. No Limits" series.

LaVallee, of Longville, Minn., was scheduled to attempt his snowmobile jump last New Year's Eve in snowless San Diego but was seriously injured in a crash during training two weeks earlier.

Now, he wants to break his world record of 361 feet, set hours before his painful wipeout.

Maddison, an Australian who lives in Southern California, wants to jump 400 feet, which would break the current record of 391 feet for the world's longest motorcycle jump.

The ESPN broadcast will begin after the Chick-Fil-A Bowl, with the jumps set for midnight EST.

Maddison is a veteran of the Red Bull series, including his spectacular feat three years ago when he jumped onto and then off the 96-foot high scale version of the Arc de Triomphe at Paris Las Vegas.

A snowmobile jump of this magnitude might seem a bit bizarre, but LaVallee intends to make it work.

"What we're doing is solving the impossible," LaVallee said this week. "People ask me, 'Is this the end? Is this as far as you can go?' I always say that nothing is impossible; it just hasn't been solved yet. That's what we're doing out here. Nobody's done this. It's what we plan to do on New Year's Eve."

If it works, it's sure to be eye-popping.

"It's a feat that no question about it has never been done before, so I'm excited about it," Maddison said. "Levi's a great athlete, so I have all the faith in him. I'm confident it's going to go off well."

A lot can go wrong, though, as LaVallee found out the hard way last December. While practicing at the speedway in Fontana, a problem with the carburetor caused his engine to cut out, and the sled slammed skis-first into the landing ramp. LaVallee fractured his pelvis, broke several ribs and both lungs collapsed.

LaVallee said his Polaris snowmobile now has an engine with electronic fuel injection, which should eliminate the problem that led to the crash.

Maddison and LaVallee will stagger their run-ins by a second or so, largely for safety and also because the stunt will be filmed from the side.

"When you're doing 110 mph, that's a big enough gap to make it comfortable," Maddison said.

One crash was bad enough. LaVallee doesn't want one that might take out both riders.

"The biggest concern is, gosh, with the snowmobile, it's like a kite flying through the air," LaVallee said. "It catches so much wind that I kind of drift left to right quite a bit. The last thing we want is to have us run into each other in the air. Even more so on the landing ramp would be where it would happen. If I started to land a bit crooked, I don't want to shoot over and run into Maddo and cause him to crash as well."

Due to problems with Maddison's bike, the two made only one practice jump together at Fontana.

"We know what we have to do," said Maddison, who kick-started the Red Bull series in 2007 by jumping his motorcycle 322 feet in Las Vegas. "We were able to do some runs without jumping, where we had different start points. We were able to get our timing down, so we know when he needs to leave when I go a certain distance. The way we timed it we should be able to get each other right side-by-side. It's a bit of a tricky thing to time but we think we have that dialed in."

Maddison said if the wind is up and shifts the flight of his bike, "it could be pretty catastrophic. As long as you have your momentum and the speed doesn't diminish by mechanical failure, you're pretty good."

He also discovered that little movements "can make massive changes to the way the bike flies. So for me it's all about staying tucked in and as small and aerodynamic as possible."

LaVallee said the first thing he did when he got to San Diego this week was walk to the top of the takeoff and landing ramps.

"It's awesome," he said, noting that flying over water and the large boulders that line the shore will be different than going over concrete and grass at the speedway. "It looks way gnarlier than during the testing that we did."

Maddison has jumped the 279-foot wide Corinth Canal in Greece, at a height of more than 300 feet above the water, and did a no-handed back flip over the open span on London's Tower Bridge.

Maddison said this jump might not be quite the spectacle as his Las Vegas stunt in 2008, but it will still be extreme.

"The jump I did in Vegas, I think it kind of maybe scared a few people involved in this," he said. "It's become more of a harder thing to do now, because people realize what can go wrong with those things. My goals are to go out and do stuff beyond that. I saw how people enjoyed that thing, and I want to take that to kind of new heights in the future."