Merc alpha4 prop question

[rs1lollie]

I recently bought a mercury alpha4 4 blade prop, put it on and its like I have a new boat, BUT, today out and about it was my wife, daughter and myself out cruising the St. Croix river and at 15-20mph with my wife and daughter sitting in the bow (225lbs) , the boat wants to pull to the left, (alpha1 outdrive 3.0l mercruiser) trim tab is maybe about 3 degrees to the right looking from the top. My Question is on the box that the prop came in it says, (Flat Tab Anode is Required)
. so should I replace my trim tab with a flat one, and would this cure my pulling problem???

 

[Fun Times]

Re: Merc alpha4 prop question

It should help with some of it.

You really do need some good size clearance between the prop and the Anode, And that is ware the flat anode comes in to play to help with some of the steering pull in most cases.

But normaly the flat Anode is for power steering, And the fin is for outboards and none power steering style boats for the most part to help counter some steering torqe by the prop.

Dose your engine have Power steering???

Did your boat run the same way if and when you put your wife and daughter in the rear area of the boat?

http://sites.mercurymarine.com/port...26_49291:126_49299&_dad=portal&_schema=PORTAL

 

[rs1lollie]

Re: Merc alpha4 prop question

No I do not have power steering and yes it pulled with them sitting in the rear. I do have about 3/4" of clearance between the prop and trim tab. So do you think if I center the trim tab it would act like a flat, or just get a flat one?? Would I have a harder time steering with prop torque without a trim tab??

 

[hwsiii]

Re: Merc alpha4 prop question

Lollie, leave the one you have on there and adjust it to make steering torque neutral. Yes you need it and it will help.


H

 

[Fun Times]

Re: Merc alpha4 prop question

No I do not have power steering and yes it pulled with them sitting in the rear. I do have about 3/4" of clearance between the prop and trim tab. So do you think if I center the trim tab it would act like a flat, or just get a flat one?? Would I have a harder time steering with prop torque without a trim tab??

More then likely, I would first try adjusting the fin first a few times to see if you can make it better, Because of no power steering.

 

[BigBoatinOkie]

Re: Merc alpha4 prop question

the boat wants to pull to the left, (alpha1 outdrive 3.0l mercruiser) trim tab is maybe about 3 degrees to the right looking from the top. :

I believe you need to turn the tab in the direction that the boat is pulling. If it pulls left, turn the tab left. In your case, the tab being turned to the right may be causing the pull.

 

[rs1lollie]

Re: Merc alpha4 prop question

Thanks for all the feedback guys, it sound like I have to tinker with the trim tab. With the prop spinning clockwise, I should trim tab be set to the left??
( turnig it clockwise looking down at it)

 

[hwsiii]

Re: Merc alpha4 prop question

Yes



H

 

[rs1lollie]

Re: Merc alpha4 prop question

thanks HWSIII, I will mess around with it this weekend and inform you all.

 

[hwsiii]

Re: Merc alpha4 prop question

That sounds great.


H

 

[rs1lollie]

Re: Merc alpha4 prop question

I got my trim tab adjusted, man a lot of go and stop to adjust and go again, but I got it. I also brought my laptop out with ms streets and trips on it so I could get a gps speed. 42mph at 4800rpms is the fastest I got with it trimmed out. not bad for a 3.0l 135hp mercuriser with my daughter and myself and 3/4 tank of gas.

 

[hwsiii]

Re: Merc alpha4 prop question

That is good to hear Lollie, I am glad everything is working right.


H

 

[Fun Times]

Re: Merc alpha4 prop question

I got my trim tab adjusted, man a lot of go and stop to adjust and go again, but I got it. I also brought my laptop out with ms streets and trips on it so I could get a gps speed. 42mph at 4800rpms is the fastest I got with it trimmed out. not bad for a 3.0l 135hp mercuriser with my daughter and myself and 3/4 tank of gas.

I knew it would take a few times to get it just right but it sounds like it was worth it. Glad you got it and thank's for letting us know.

 

[rs1lollie]

Re: Merc alpha4 prop question

Thanks guys for all your input and help!!! Iboats is awesome!!!!!

 

[BigBoatinOkie]

Re: Merc alpha4 prop question

glad you got her fixed up man.