Brad Christy

LTZ,

This is pretty much the consensus from anybody I've spoken with who understands physics. The engine imparts torque against the hull, seen as twist in the frame of a drag car, for example, but not seen in a boat, since there is essentially no separation between the engine and outdrive, while the prop imparts torque against the water, which is the cause of our "torque roll". Running a LH prop will only impart that torque the other way, all other factors aside. Pretty much the only thing that will actually counter prop torque is an opposing force imparted against the water; a trim tab, for example, or hull work, like exaggerated strakes on one side. One could also reduce the amount of torque imparted to the water with prop work, such as sharpening, thinning, or pitch progression. I've also seen a few struts on model boat V-hulls that were machined so that the prop shaft was set on an angle relative to the direction of travel, but the strut body was straight, that was done specifically to counter prop torque. It seems to work. I don't know if this would prove effective, but it would be a LOT of work to test in our full-size boats. My guess is that there was a lot more done to the boat/drive/prop, that has not been divulged, that went into the success of the Checkmate in question. It wouldn't surprise me at all if they tossed out the "We run a left-handed prop" as a way of warding off any further questions, while keeping the remaining efforts close to their chests.

Thanks. Brad.
(937)545-8991

cougarman

Ton's of Guru's on OSO if ya keep your ears on, then entire reason OSO was started was sharing.
Real Life Experience is usually your greatest teacher.

Brad Christy

Cougarman,

Real life experiences led us all to believe that waxing the bottom of our boats made them faster. I can also remember hearing my dad and his friends discussing that conventional wisdom was that the deeper the outboard, the more stable the boat. Turns out, once the physics was explained, we'd been wrong all along. We often perceive what we are seeking in results that aren't there.

As I asked before.... Why are the V-drive guys still using a trim-plate to counter torque roll? They are already running their props opposite the engine. How is it the boats with duo-prop drives aren't slammed to one side, given that the prop torque is already mitigated by the counter rotating props, with the supposed torque imposed by the engine not mitigated? And how is it that Merc hasn't figured this "secret" out yet, given the uncountable hours they commit to R&D every year? The answer is that engine torque is absorbed within the mechanism, and not rendered by torque roll of the hull. The next question is, "How did Check300 ACTUALLY mitigate prop torque?" There are those who would like to know, and not have to waste a bunch of money on a new prop and drive work, only to find their boats leaning the other way.

I understand there are many great minds here on OSO. So far, the only reply here with any actual first-hand real-world empirical evidence, guru or not, has stated the only effect of running a LH prop on a single engine boat was that the boat prop rolled the other way.

Thanks. Brad.
(937)545-8991