Unsafe Torque Steer Help Please

[jrockG3]

Even with the trim up, no matter the jack plate height, I need two hands on the wheel, as it pulls right! It’s an 18’ G3 Bay DLX w 115 Yamaha, 6” jack plate, 3 blade SS prop (right turn), sponsons on stern, mechanical steering helm. Straight skeg, straight prop, proper CG, and no hooks in the hull, so it seems related to the set up (sponsons, Rear weight, jack plate height, prop). I already set zinc torque tab as far right (trailing edge) as it will go and it barely helped. I know cavitation plate level should be level or 1” above hull, but mine is 2.5 to 7” above hull (w jack plate set from lowest to highest positions). See pics. That said, the back is heavy, so even with the sponsons, the stern sits low enough the cav plate and prop are below water, even with the jack plate up high. Could this high position cause the right pull? I thought the lower the motor, the worse the pull...

I’m considering adding an aluminum torque tab along the length of the skeg (pic), and then maybe NFB helm also. Appreciate ANY help!!

 

[Chris1956]

On those high performance set ups, the zinc anode can be out of the water at planing speed. If out of the water, they provide no steering assistance.

Provided your motor is getting enough water, a torque tab may be the answer. I use one on my speedboat and it works pretty well.

 

[dingbat]

Looks to me like the motor is roughly 5” too high according to the owners manual.

Is the jack plate after market?

https://www.g3boats.com/wp/wp-conten...-optimized.pdf

 

[jrockG3]

Chris1956, thanks for the response, I hope you’re right. It will at least be an easy job.

dingbat (I almost feel like I’m insulting you!), really appreciate your research, I’m impressed. I agree, looks high to me too, but that exactly the way it was delivered. I ordered it with the sponsons and jack plate (was the dealers recommendation as well), so I’m sure the set-up is G3 approved. However, the G3 dealer rigs the boat, so it’s possible they set it up incorrectly...I will have to subtly ask them??

 

[dingbat]

However, the G3 dealer rigs the boat, so it’s possible they set it up incorrectly...I will have to subtly ask them??

Never be afraid to ask.
A neighbor (not a boat guy) had his Welcraft repowered a couple of years ago. He complained about the same problem.

Met him at the marina a week or so later. Nothing obviously wrong so I took it for a spin. Never piloted a boat that hard to turn.

Something about the motor.... just looked odd on the boat.

Went home and did some research. Turned out they installed a 25” motor on a 20” hull.

The shop told him that’s what the parts department ordered for his boat. Take it up with them. Took getting a lawyer involved to get the proper motor installed.

One of the larger local marine dealers with a not so good reputation.

 

[jrockG3]

Wow, that’s a crazy scenario, thanks for sharing. I agree. If I did not get the jack plate, I’m curious where they would’ve set it up, so I think my best bet is to ask them where they rig without the plate and go from there. Seems to me, the plate should allow a safe height range above and below the “normal” fixed level, which I would expect to be level with bottom of hull to a couple inches above...I imagine the torques steer is bad at higher speeds when I’m on plane because the torque tab is barely under water at that point. I also understand the pull is worse the lower the motor is in the water, so I believe it makes sense that the plate should at minimum allow the motor to go down to at least w cav plate level or slightly below the hull...any thoughts?

 

[jimmbo]

I'll be surprised if you don't have water starvation problems
At those engine Heights, a Torque Tab, as mentioned by Chris, is usually needed/added


You really need to get a Prop that is Designed to run partially Submerged

 

[jrockG3]

[No message]

 

[jrockG3]

Jiimbo, thanks for the advice. I installed exactly what you posted! Took me forever to find that tab for the skeg, but I’m glad I did. I did a trial run yesterday and it actually worked. It’s a bit complicated because I also have the smaller torque tab above the prop, so I have two that I can now adjust. Interesting, because the skeg tab is always in the water and works almost too well for the WOT on plane situations (actually over compensates a bit and now pulls a little left), but I can file off some of the raised curve to reduce its effect. The original tab above the prop can also be adjusted, of course, and I have it set a couple notches to the right (trailing edge to right) to add more correction. I just set it that way to start off my initial trial run. At slow speeds not on plane, it still pulls a bit right...hard to believe, but I can trim it out. So I’m leaving that tab as it is. I think I’ll file down a bit of the skeg tab to reduce the high speed correction.

Far as props go, I think you’re right about water starvation because I can hear it at high RPMs. Do you have any suggestions on a prop for these conditions? I’ve heard 4 blade props are better to reduce the torque steer, but have no idea if it also works better for water starvation. I assume it would, though, since you have one more blade to engage...many thanks for the advice!!

 

[Chris1956]

Gee, deep six the whale tail. You have a high performance boat, not a barge.

Normally when props ventilate, they are close to loosing cooling water. Do let that happen, or it can cook your motor.

 

[jimmbo]

Raising the Engine is the reason of Water Starvation, no Prop is going to cure that, Gearhousings that are intended for Raised Engine Heights will have Water Inlets at much lower Locations, even on the front of the Gear Case Bullet. In past there were aftermarket Nose Cones with Water Inlets, thee required Drilling, Fitting and Hoses to get water to the Water Pump, in addition there have been many other so called Solutions, but I'm sure they resulted in many Overheated Engines