OMC I/O sway at low speed.

[Charles Ramsey]

I have a 1992 4Winns with an OMC outdrive. At low speed the I/O sways back and forth and I consistently have to adjust my course however this does not appear to happen at high speed. Any suggestions on what the cause(s) may be?

Thanks.

 

[Bondo]

Re: OMC I/O sway at low speed.

Ayuh,... It's typical V-hull wander...

 

[Fishermark]

Re: OMC I/O sway at low speed.

I'm not too familair with OMC - but does the outdrive move back and forth by hand when out of the water? In other words, is there a lot of play in the pivot points / steering?

 

[airdvr1227]

Re: OMC I/O sway at low speed.

Best fix is to find a point off on the horizon and aim for that. You'll get used to it...or as in my case I just got tired of the constant correcting. Easy to ignore when it's not crowded.

 

[jkust]

Re: OMC I/O sway at low speed.

Just stop correcting and you will go in slight zig zag straight course. It threw me for a loop when I went from OB to I/O too. I really only notice it in narrow channel's with oncoming traffic. Counter rotating props help.

 

[HT32BSX115]

Re: OMC I/O sway at low speed.

Counter rotating props help.

Um, not really. It's a function of "pushing" a "Deep-V" hull... Not the drive type

Mine didn't change at all when I pulled out the Wunderful high tech 460 King Kobra and replaced it with the Mercruiser Bravo III.

It still does it the same at the same speed


It really doesn't matter what's pushing the boat. If it's a deep V (with a pusher-drive), it's going to wander.

Actually all boats do it to a certain degree. If you had a deep keel, or fin, like a sail boat, it wouldn't do it as much, or at all.

Because the thrust is behind the center of mass, and there's little or no real keel, the force of the drive is also partially responsible for the longitudinal (yaw) oscillation.....that little bit of keel(because of the deep v) is just enough to pull it back towards center and slew to the other side.......

If the drive was in front (in a "tractor" configuration) it would not do it at all! That would look pretty weird though!!!



Cheers,



Rick

 

[Fishermark]

Re: OMC I/O sway at low speed.

At low speed the I/O sways back and forth

What everyone above says is absolutely true.... I guess I took your original post to mean that the actual Outdrive is swaying.... like it has too much play in it.

 

[HT32BSX115]

Re: OMC I/O sway at low speed.

What everyone above says is absolutely true.... I guess I took your original post to mean that the actual Outdrive is swaying.... like it has too much play in it.

Actually I'm reading the same thing! That, of course exacerbates it!

 

[Gary H NC]

Re: OMC I/O sway at low speed.

Every I/O drive i have owned has done this. An easy fix is Smart Tabs or helm adjustable trim tabs.
On my last boat the smart tabs eliminated the wander completely.

 

[HT32BSX115]

Re: OMC I/O sway at low speed.

I have heard this claim before.

You know it's funny......but that doesn't seem to help either. I have Bennett Trim Tabs installed too.

Every combination of settings (including FULL-DWN) didn't affect the longitudinal stability at all. It still wanders at the same speed.

I don't know how a spring loaded tab would be any different. At low speed (idle, which is where this "problem" is most prevalent) Any spring loaded tab would also be full-DWN applying equal drag to both sides.


Perfectly flat bottom boats do not "wander" since they don't have any keel at all. When the heading moves slightly left or right, with no keel, there's no "force" to pull it back to center (unless the operator moves the engine/drive/rudder etc) so it just keeps going to the left or right. Most people do not recognize this as wander.


With a deep vee or keel, when the boat drifts left or right, (with no operator correction) it "yaws" sideways and slowly comes back to center.......then crosses center to the other side........ the same thing happens all over again in the other direction


The only effect of dragging 2 "sea-anchors" in the back would be to slow the boat down (at the same idle-rpm) This would slow the oscillation probably enough to not notice but not eliminate it altogether.....(of course if you don't notice it, it's gone, right?)

If the actual boat speed is increased to where the keel is more effective, the oscillation is stopped altogether.


If you look here on iBoats and just about ALL of the other boating sites, this is talked about all the time.....I know it's here in several threads.....


It's not an I/O issue exclusively......

 

[jkust]

Re: OMC I/O sway at low speed.

Um, not really. It's a function of "pushing" a "Deep-V" hull... Not the drive type

Twins

 

[Boatist]

Re: OMC I/O sway at low speed.

It really should be called V hull Wander.
Once you learn not to over steer and not try to correct ever slight change in direction you will be fine.
Outdrive has very little to due with it. It not the stern changing Direction like you were steering with the motor. Most times the direction will come right back in a short time even if you do not turn the wheel.

So the key is to not try and correct every change in direction. Only turn the wheel slowly to maintain your intended direction and stay in the channel.

Changing speed a small amount can make a big difference.

 

[HT32BSX115]

Re: OMC I/O sway at low speed.

It really should be called V hull Wander.
Once you learn not to over steer and not try to correct ever slight change in direction you will be fine.
Outdrive has very little to due with it. It not the stern changing Direction like you were steering with the motor. Most times the direction will come right back in a short time even if you do not turn the wheel.

So the key is to not try and correct every change in direction. Only turn the wheel slowly to matain your intended direction and stay in the channel.

Changing speed a small amount can make a big difference.

Yup!

 

[sqbtr]

Re: OMC I/O sway at low speed.

Every combination of settings (including FULL-DWN) didn't affect the longitudinal stability at all. It still wanders at the same speed.

I don't know how a spring loaded tab would be any different. At low speed (idle, which is where this "problem" is most prevalent) Any spring loaded tab would also be full-DWN applying equal drag to both sides.

It probably depends on the size of the boat. I didn't see the OP post the length. Smart tabs on my 17 footer made a huge difference in wander

 

[superbenk]

Re: OMC I/O sway at low speed.

Installed Smart Tabs for this very same reason & found them to be enormously helpful. It didn't eliminate the wander, but it certainly helped quite a bit. Made the boat feel more stable in general as well.

 

[HT32BSX115]

Re: OMC I/O sway at low speed.

Installed Smart Tabs for this very same reason & found them to be enormously helpful. It didn't eliminate the wander, but it certainly helped quite a bit. Made the boat feel more stable in general as well.

Since they're also spring-loaded and add drag at all speeds they'll reduce your top end a bit too.....

My Bennett Tabs also slow the boat at top speed.


I don't think there's many out that care if they get a little slower top speed though if the low speed handling is improved or the planing speed is lowered a bit..............


When I pull wake boarders, I run the tabs all the way down and run the drive all the way IN...... the bow is considerably lower at the right wake-board speed this way.

If I want to go fast.....I run the tabs all the way up and out of the water.....

 

[Gary H NC]

Re: OMC I/O sway at low speed.

I agree with ya HT...I just know on my 19 footer the tabs made a huge difference.Maybe it is the extra drag that helps?

 

[superbenk]

Re: OMC I/O sway at low speed.

Since they're also spring-loaded and add drag at all speeds they'll reduce your top end a bit too.....

I don't think there's many out that care if they get a little slower top speed though if the low speed handling is improved or the planing speed is lowered a bit..............

It's hard to care when you're talking 34MPH vs. 35MPH My boat just doesn't go that fast. The handling improvements have been very worth it.

 

[Seon]

Re: OMC I/O sway at low speed.

I had a 19' Reinell cuddy with smart tabs and didn't wander. But sold that boat and replaced it with 21' Trophy that wandered something crazy. Sold that and bought another 19' Reinell cuddy similar to the 1st Reinell but without the smart tab and discovered it's wandering like the Trophy . I guess I'll have to either install smart tabs or live with the wandering :redface:

 

[Home Cookin']

Re: OMC I/O sway at low speed.

interesting--I recently took a 19' Grady CC for a test run and it wandered like crazy at "no wake" speed. Never seen anything like it. The steering wasn't loose but being hydraulic it was very light. But my 21' Sea hunt and friend's 22' bay boat (he was with us) doesn't wander at all--and my tabs presently are out of order and all the way up.
It's hard not to overcorrect but that is what we'll need to learn.

I wonder if changing weight displacement would help, or trim? get the bow up some and the V out of the water? I guess dead rise will be a factor among hulls as well.

Good suggestion about looking at a distant point 9once you get used to the steering); that works on bikes and canoes as well.