89 Larson I/O leans left while driving??

[jamOner]

Hello, I have a 1989 Larson open bow, with an I/O Mercruiser 3.0 & alpha one lower unit. Last week I took it to the lake and noticed that it leans to the left (only while driving, it sits fine in the water at slow speeds or parked), and dont know what the problem is. While driving straight ahead, it seems as if the left side is lower in the water, and it is a lot harder to steer right then left. Also while making a left turn at any speed above 10mph, it is almost scarey as if the left side is almost in the water. Any suggestions what the problem is? Attached is a terrible illustration of what I mean.

*note, there is nothing in the boat other than the normal seating, myself and a friend, so there should be nothing weighing it down on the left side..
** also, neither the prop nor fin on the lower unit is bent - I checked those first.

 

[rndn]

Re: 89 Larson I/O leans left while driving??

Did you check the trim tab? This will help the boat track straight.

 

[Jdeagro]

Re: 89 Larson I/O leans left while driving??

Here are a few questions:

1) how long have you owned and opperted this boat?
2) what have you done to this boat recently? ie: have you added a hydrofoil to the cavitation plate?
3) Are you trimming the motor up once you are on plane?
4) have you check to see if there is a steering trim tabs on the bottom of the cavitation plate (looks like a small rudder) and if it is secure.?
5) have you changed propeller?

Waht you seem to have is a torque list which could be caused by some or any of the above.

 

[jamOner]

Re: 89 Larson I/O leans left while driving??

Did you check the trim tab? This will help the boat track straight.

No, how do I check the trim tab?

Here are a few questions:
1) how long have you owned and opperted this boat?
2) what have you done to this boat recently? ie: have you added a hydrofoil to the cavitation plate?
3) Are you trimming the motor up once you are on plane?
4) have you check to see if there is a steering trim tabs on the bottom of the cavitation plate (looks like a small rudder) and if it is secure.?
5) have you changed propeller?
Waht you seem to have is a torque list which could be caused by some or any of the above.

1.I have only owned the boat 2yrs, and have taken it to the lake less than 5 times.
2.Not sure what az hyrdofoil is, but my lower unit does have plastic pieces mounted to the top (and I have noticed they are aftermarket since my uncle's alpha one doesnt have them).
3.No, I did not try to trim it up once I was planed out, but should probably do that.
4. Yes that "small rudder" thing (I think what you are talking) is there and secure.
5.No I have not changed the prop, but this could have always been a problem even before I bought the boat.

thanks everyone! hopefully I can get this figured out!

 

[QC]

Re: 89 Larson I/O leans left while driving??

1) remove the hydrofoil (plastic aftermarket POS mounted to your anti-cavitation plate)

2) adjust the little rudder thingy (trim tab) until you get neutral steering effort both directions at a comfortable cruise speed. Steering effort will change at different speeds without Power Steering. You want it reasonably equal at the point you will operate her most:

3) If she still lists uncomfortably to port underway this is caused by the rotation direction of the propeller: it turns one way, the boat leans the other . . . All single prop drive boats do this to some degree. If it is really bad, you will need hull mounted trim tabs (see item #4)

4) Without the hydrofoil she may not plane as slowly as she does now. If you want or need lower planing speeds, or if you need help to get her on plane, you should add trim tabs to the hull (not the same as the little drive rudder thingy). SmartTabs would be great for you and your hull. They are available right here on iboats . . .

 

[rndn]

Re: 89 Larson I/O leans left while driving??

Nice description and drawings QC.

 

[jamOner]

Re: 89 Larson I/O leans left while driving??

Awesome! Thank you guys for your help, I will try all of the above in the next few days then take her back up to the lake. Thanks a ton!

 

[Jdeagro]

Re: 89 Larson I/O leans left while driving??

The hydrofoil will lift the stern more and more as the speed of the boat increases. Once you are on plane you do not need excess lift, and infact it will cause handling problems. Next; when you leave the outdrive trimmed all the way down, it angles the prop upward to lift the stern which is a big help when accelerating to plane. However; once it is on plane this works against you in the same mannor as the hydrofoil. It drives the bow down. This cause the following:
1) a list to the port side because the boat is riding too much on the keel, and the prop torque causes a counter rotation force.
2) with the bow down the boat will "bow steer". Very sensitive to control.
3) a loss of top speed
4) a loss of fuel economy

 

[bushman10]

Re: 89 Larson I/O leans left while driving??

I can relate to your frustration as I just recently purchased a 2007 Larson LXI 5.0 MPI with Bravo 3 drive and it leans to the starboard side about 10 degrees while in motion and even after at crusiing speed and planed out. I don't feel I should have to buy trim tabs for a "brand new boat". If this is a characteristic of this boat with the Bravo 3 drive then the manufacture should have trim tabs on these boats as standard equipment? I love the boat otherwise and the Bravo 3 drive really gets it up and planing right away. Maybe the torque of the B3 drive is what is causing this starboard list? Is it possible to pull one of the props off and put it back on a different spline to change the list??

 

[valkyr]

Re: 89 Larson I/O leans left while driving??

Hello, I have a 1989 Larson open bow, with an I/O Mercruiser 3.0 & alpha one lower unit. Last week I took it to the lake and noticed that it leans to the left (only while driving, it sits fine in the water at slow speeds or parked), and dont know what the problem is. While driving straight ahead, it seems as if the left side is lower in the water, and it is a lot harder to steer right then left. Also while making a left turn at any speed above 10mph, it is almost scarey as if the left side is almost in the water. Any suggestions what the problem is? Attached is a terrible illustration of what I mean.

*note, there is nothing in the boat other than the normal seating, myself and a friend, so there should be nothing weighing it down on the left side..
** also, neither the prop nor fin on the lower unit is bent - I checked those first.

Bah! Too many liberals aboard!

 

[QC]

Re: 89 Larson I/O leans left while driving??

Welcome to iboats bushman. You really should start your own thread to keep your issues seperate from jamOner's, but I have given you a couple of quick answers below . . .

Maybe the torque of the B3 drive is what is causing this starboard list?

Because of the counter rotating propellers, Bravo 3's do not cause propeller torque list . . . I am guessing you have a weight distribution issue.

Is it possible to pull one of the props off and put it back on a different spline to change the list??

That would have no effect . . .