Trim or Torque Tab Question

[NBE]

When trimming the motor while running WOT (or close to it), is there a point that you could reach where the adjustable trim/torque tab loses its affect?

I ask this because my boat steers fine until you reach the top half of the trim range and then it pulls to the right pretty bad. The trim tab is adjusted almost all of the way to the right and boat steers fine in all other trim positions.

I am not close to the end of the trim range of the motor. For those familiar with a Yamaha digital trim gauge, once I reach 4 and above on the gauge the boat starts pulling to the right. I have maxed out the gauge without the motor cavitating but I can barely hold the boat straight so I know I have a lot of trim left to go.

The motor is a Yamaha 150 VMAX 2 stroke carbed model. The motor is mounted to center on the boat. My skeg is not bent. No jackplate and running stainless steel prop. Just wondering if it is possible to reach the point where the tab is not affecting the motor and torque is taking over.

Thanks!

 

[Reel Poor]

Re: Trim or Torque Tab Question

What kind of boat and how fast are you running? mph?

 

[ziggy]

Re: Trim or Torque Tab Question

i don't know for a fact, but i think yer supposed to adj the trim tab to operate its best at whatever trim and speed you most typically do. the tab will have different effects at different speeds and trims. so ya want to set the tab to where you like the trim and speed at. adjusted all the way to its limit don't sound right to me either. have you tried adj. the tab back more to center? see what the effect is?
be carefull from what you discribe there. when i was a kid i adj. dad's trim tab too far once (mid 70s glastron w/ merc 900). at speed and trimmed up i got me a bad case of chine walk. that became very pronounced, very fast. i felt i was fourtunate not to have fliped that boat...... i adj. it back twards center real quick after that little episode.....

to me in therory or just looking at a tab. i don't think it looses it's effectivness at speed. the water is comein right down the bottom of the vent plate, get's motivated by the prop and the first thing it encounters is the tab that can change the direction of water travel as it crosses past it......

that's my best guess not knowing anything about it.....

 

[Jdeagro]

Re: Trim or Torque Tab Question

Are you running a hydrofoil?

 

[Chris1956]

Re: Trim or Torque Tab Question

NBE, Motors with right hand props (the standard ) normally pull right. As you trim them up, the pull becomes less and less. At high trim angles, the boat may pull left. Nomally you should set the tab so the boat doesn't pull at the speed/trim angle you most often run.

On a high performance set-up, the motor is sometimes mounted higher on the transom. Sometimes the trim tab doesn't touch the water, which means it has no effect, at high speed. In that case, you want to set it so the boat does not pull at slow planing speed.

 

[NBE]

Re: Trim or Torque Tab Question

The boat is a 19' Xpress with the 150 Yamaha. The tab is about 3/4 of the way to the right. No hydrofoil, wouldn't have one. Would have smart tabs if I wanted something like that 8). Just a stock or standard set-up. Weight balance in the boat is even, no list to one side or the other because of weight.

The boat steers perfectly from no trim to when I reach the point where it starts to pull to the right. I have not tried to adjust it so far because of how great it steers at all speeds and at all trim ranges until I get to the point where it pulls. I could practically let go of the steering wheel if I so desired it steers so well. Even when coming on plane from a dead stop.

The speed varies depending on how much throttle (3/4 to wide open) but usually in the mid 40s to mid 50s. To be honest I do not run it wide open when trimming past the point where it starts to pull. I have to really hold on to it to keep the boat straight when trimming higher. I doubt that I could get it all the way on the pad because of not being able to trim it out more.

Like I have said, boat steers great until I get to that higher trim range and then you had better hold on tight to the wheel. It's not that big of a deal as I like how it handles at the speeds I like to drive. Just was trying to figure out why it does great at all speeds and trim until I reach that point of trim level.

 

[NBE]

Re: Trim or Torque Tab Question

^
Bumping

Anyone else have any comments or suggestions?

Thanks!