phragle

Hell, my boat leans revving it in neutral. you have spinning inertial mass. if you swap the prop rotation, it counters it.

Dragracer_Art

Try running an engine on an engine stand.

It will roll right over if it's not supported... so there are definitely "forces at play" inside the boat before the prop even touches water.

Brad Christy

Phragle,

Mine does, too. I'd bet about any big block does. But, if you were to stay in it, it returns to level as soon as the acceleration was done.

Torque roll is prop torque, not engine torque. The engine it is inducing torque on the hull, but it's contained withing the hull, between the engine and the outdrive. The prop, however, is inducing torque on the hull, but it's doing so against the water, which is not contained within the mechanism.

I don't think the physics are there for the reasoning in question. I'm not denying the success in the set-up. Just doubting the methods credited to the success. I'm guessing there's more to the prop than it just being left-hand. I'm betting its sharper than a deli slicer on the leading edges.

Thanks. Brad.
(937)545-8991

cougarman

Not uncommon for the racing teams with Twins to also run one of the Engines with Counter Rotation & Firing order too.
(At least in the past, not sure if still a practice especially if running factory M Power)

Brad Christy

Cougarman,

Completely understandable, as those are opposing forces that can be utilized to an advantage. The last thing you'd want is for acceleration torque to be imparted on the hull when the throttles are dumped while the boat is clear of the water. You use any counteracting forces available when you can. But that's twins....

If it were as simple as rotating the prop opposite the engine to counter prop torque, what's keeping Merc from doing so in all their drive packages? Why isn't engine rotation translated into torque roll with a DuoProp drive, where actual prop torque is already countered? Watch a V-drive torque roll when they hammer the throttle; they already run the engine opposite the prop.

I know the single most effective work that can be done to a prop for a V-hull model boat is to sharpen and thin the leading edge to reduce the resistance the prop experiences as it is forced through the water. The second is to reduce the progression of pitch, but that opens an entirely difference can of worms, greatly affecting engine load respective to average effective pitch.

I'm convinced there's more to the story than, "We run a left-hand prop. Wasn't that easy....?" The key to enjoying the same benefits they gained is to understand what that "more" is, and it ain't in the low hanging fruit.

Thanks. Brad.
(937)545-8991

cougarman

For years we were told we Turbo's didn't work in boats too, Then Mercury came to the table with Turbo's
Now they work

Brad Christy

Cougarman,

OK.... And....?

Merc didn't reinvent the wheel. Turbos have always worked under the right conditions. The boats got large enough we don't expect them to come on plane very quickly, and we stand on them pretty hard to get them there. That's where turbos shine. That's also why we don't see turbos on Top Fuel engines. And we still have issues with the one problem with turbos that can't be easily mitigated: Heat. Larger boats have much larger engine compartments that can be exploited to dissipate vent the heat better. Besides....

What does that have to do with torque roll? The question was asked about what causes torque roll. The answer lies in the dynamics involved in the prop in the water. I just think there's more to it than just the rotation of the prop, and the questions and examples I posed support that. I'm hoping some physics guru will chime in and tell us yea or nay on the theory of it. I've got a buddy working on it who excelled in physics in high school and minored in it in college. He's pretty much the smartest guy in the room, whichever room he walks into. I'm hoping he can come up with a visual representation that explains it one way or the other.

I'm not doubting the success story here. The proof's in the pudding. But the recipe is usually a secret.

Thanks. Brad.
(937)545-8991

Ultraboy

I am not a physics guru, but did talk to the Powerquest dealer at LOTO about the “torque roll”, or the likelihood of the single engine, single step (Powerquest) boat to lean towards the port side. His solution was to run a left-handed prop.

I also heard this is the solution on the 29 fountains with single engines.

My Powerquest 280 definitely leans to the port side even when there is a relatively equal weight distribution side to side.

LTZCrew

good reads

that checkmate looks killer, super sweet sleeper!
i wonder if a turbo motor would exhibit less torque roll at lower loads due to less boost over a blower motor?

I tried a left hand prop. had read about fountain doing it and hoped that would be my fix. sadly it just leaned the other way. haha. i was thinking the same thing about drive rotation offsetting Eng. rotation. but no dice

i don't get any chine walk and i don't touch the tabs at speed - only use for sub 60's to off set loading and such. . they hit like letting a parachute out on anything faster.
thinking maybe some deeper single step V's just want a &^(( of trim?. going to try sending a prop out to add some bite to keep the slip down when its trimmed sky high or see if i can get my hands on a 29" 5 blade.

cougarman

Turbo's do ok...