From the comments above it does not sound like anyone has a clear understanding of how propeller design contributes to list. It only takes a couple degrees on a sloppy installation and the boat will torque/pull to the left or right pending the angle. On plane, at higher speeds the prop torgue is pretty much out of the picture, (depending on the boat). Off My Dock: Demise of the Braggin’ Board. The steering is so easy now that there isn't enough resistance in the system to overcome the prop torque at higher speeds. If I had done that on my Montauk I would have ended up on the river bank. When I bought my boat, which is equipped with twin V-6s, both motors were standard rotation. On my boat, a 22-footer with Whaler Drive, I find that moving one crew from outboard to centerline or vice versa will usually compensate for any lean. To reduce the tendency for the hull to list, we can change the static forces and the propeller forces. The force generated by one blade of a three blade prop are identical to the forces generated on the opposite side of the prop as the other two blades, being at an angle, are at decreased distances from the prop shaft and of the boat CG. I never had a clue that a propeller change could make such a difference and I still don't understand why it has changed all it did. If those bolts were removed - the engine would flip off the boat. He has hydraulic steering which does not allow the motor to turn the steering wheel. You won't feel this force at the steering wheel due to the hydraulic steering, but that doesn't mean it's not there. Pull on the end of the tiller handle and the valve opens allowing you to steer. The natural tendency to torque steer with the rotation of the propeller at slow speeds makes docking easier on that side. ---- Jerry/Idaho3. Maybe I'm way off base and if so I apologize. X3 mount is built tough with aircraft-grade extended aluminum to minimize flex and provide precision control under high-thrust. By trimming the motors out the propeller shaft is not level and while that, in itself, may introduce some sort of inefficiency, the lift of the hull and the reduction of wetted surface as well as reduced gearcase drag more than compensates for that. expert but it seems to me that the propeller is transfering the force from the motor into the water one blade at a time. My kicker was to port for the same reason and that was part of the problem but not all of it. Note: Left-Hand Propellers are primarily used on twin engine boats to cancel the steering torque that would be caused if both propellers spun in the same direction. Our sailboat was in a slip located such that the exit from the marina was to Starboard. Your steering … Not usually. http://media.channelblade.com/boat_graphics/templatesites/dts/dealerlibraries/8441/copetipstricks.pdf. Finally got the 19 ft Liberator tunnel back on the water and got some seat time this weekend. Though your boat speed may go down, it is still a MUCH more efficient way to start a vacation as you will arrive without your wife being pissed at you. And yes, they are beautiful. blade breaks out of the water surface as it rotates, there's a new set of unbalanced forces to consider. Running with a list is uncomfortable, as well as unsafe. Vertical - remember that water is incompressible and at the same temperature and pressure, the density will be the same. It is unusual for a standard rotation propeller to torque steer to the left unless the trim tab is positioned incorrectly or you are running a counter rotation model on your boat. Concerning the prop. Perhaps someone can expand on it.) I did a search on "rudder trim tab" and didn't find any … As to Sean's Outrage 18 with its 150 HP outboard, I note that my Outrage 18 with its 150 outboard always tended to list to port and it bugged me. I am having a bad torque steer problem. Right-hand propellers rotate clockwise to provide forward thrust. The excessive torque steer is gone, top speed increased to 49 MPH (GPS) with 2 people and full fuel and the purposing problems I had went away, all with only a 50 to 75 reduction in RPMs, it is like a completely different boat. FIND OUT MORE. Registered members Current visitors. Another one is the torque caused by the engine rotation mass with the prop against the aircraft mass. The best I could do is move as much weight to starboard, and I always moved my passengers if I could. Also Jerry, I'm far from a mechanical engineer or prop. profile | register | author help, Boat RiggingOutrage 18, Mercury Optimax 150, Enertia 16, flat anodeYamaha T8 mounted to port transomSmall fuel tank and oil reservoir in splash wellTwo Group-27 batteries in console12x12 Lenco trim tabsTransducer on starboard sideMisc. Either way moving the tabs trailing edge in the direction of the torque steer will nullify the effect at the rpm and trim setting you adjusted it at. Now, even though the upward, downward, right and left forces are balanced, those same forces provide a moment about the CG of the boat. are balanced, then why the need for a steering trim tab on the motor? Further, the larger the blades, the more pronounced the list effect will be. The result is a propeller tends to walk sideways in the direction that the upper blade tends to progress toward on its downward stroke. 4 blade props tend to have a lower top speed. It was something one learned to compensate for and actually use to your advantage when maneuvering around with some practice. Bennett Trim Tabs operate independently for effective list correction. ZERO TORQUE TILLER STEERING SYSTEM A SAFER WAY TO FISH. If you have a clockwise turning or right-hand propeller, when the shaft turns for forward propulsion the propeller tends to walk the stern to the right, producing a tendency for the boat to turn left. The front prop nut is torqued to 100 ft lbs. Can we have a more thorough explanation or a pointer to one? My new Outrage has hydraulic steering and when on plane I can let go of the steering wheel it tracks dead straight. The last is an effect produced by the first two. This will, by itself, greatly reduce the list to port but it will also reduce or negate any benefit of adding a trim tab as the tab will be mostly out of the water at speed. --steering torque: the tendency for an outboard engine to be more difficult to rotate in one direction than the other. Outboards usually have a small swim platform on either side of the motor. The set up is a 1986 Liberator 19 ft tunnel. The Uflex® ZTF Tiller systems eliminate propeller torque at the tiller handle when the driver is not actively changing direction. ZTF Tiller MC1 - Mercury Conversion ZTF Tiller. I don't know if this is the reason or not. Powered by: Ultimate Bulletin Board, Freeware Version 2000Purchase our Licensed Version- which adds many more features! Tiller steered boats are labor intensive to steer due to the constant load on the tiller from propeller torque, and the fact that the operator is positioned (while driving the boat) in such a way that maintaining control requires physical effort … Copyright © 2021 Boating Magazine. You would mirror the length and angle of the factory grind on the other trailing edge. It does NOT need to stay submerged. As the boat moves through the water the total pressure of the water on the prop is less at the top than the bottom, causing a right handed prop–which rotates clockwise when looking at it from behind the boat–to swing the stern of the boat to starboard, resulting in the boat … Scout One Carbon/ Enduro cage. Heavy steering torque may be encountered, and the driver must maintain a continuous firm grip on the wheel at all times when neither power steering nor no-feedback steering is employed (Figure 7-14). Ventilation. Running with a list is uncomfortable, as well as unsafe. Note: Left-Hand Propellers are primarily used on twin engine boats to cancel the steering torque that would be caused if both propellers spun in the same direction. On the other hand, you may lose some top speed depending on the 4 blade prop selected. The propeller shaft should I believe that the cause of this sideways component is due to a slight variation in how the blades of the propeller interact with the water. Moreover, if any part of the prop. and resulting in the horizontal plane. Your steering should feel equal in both directions. Scout NXT Full carbon. The boat generally handles well with the Enertia and the fuel economy is fantastic.

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