Motor INSISTS On Veering To Starboard!

[Kiggsia]

The used 16 foot Lund boat with 1987 40HP Evinrude has an unbearably strong pull to the right which of course becomes stronger with boat speed. I found the small trim rudder over the prop set to trim to the right and thought that was the cause. There is very little travel in this adjustment, but I set it "all the way" in the opposite direction, tested the boat, and there was no difference. I even removed this small rudder and retested and there still was no improvement, still this very strong pull to the right which makes my arm sore in hardly no time at all. I doubted that the fish finder sensor mounted to the right of the motor would cause the problem. And if the boat trim is too low in front causing porpoising, it would sometimes pull to the left I would think, and only when thrusting downward, but it is a steady pull to the right even when the water is calm and the boat travels steadily. Might anyone know what could be causing this? There doesn't appear to be anything else out of alignment. The prop doesn't appear to be bent. If my prop pitch were too great could this cause a pull to the right?

 

[Joe Reeves]

Re: Motor INSISTS On Veering To Starboard!

Trim tab should be moved in the direction of the pulling action.

 

[Dhadley]

Re: Motor INSISTS On Veering To Starboard!

Can we assume the motor has power trim?

 

[Kiggsia]

Re: Motor INSISTS On Veering To Starboard!

Originally the trailing edge of the trim rudder was all the way to the right toward pulling action. But wouldn't this cause it to steer even more to the right?.
Motor has power tilt, no power trim.

 

[Joe Reeves]

Re: Motor INSISTS On Veering To Starboard!

The trim tab being adjusted to the right, when the engine is moving forward, results in the trim tab being forced to a straight ahead position.

As such, this would result in the trim tab forcing the engine into a left turn position. Draw it out on a piece of paper, you'll see what I describe.

 

[Kiggsia]

Re: Motor INSISTS On Veering To Starboard!

I have raised the manual tilt setting where you put the long toggle pin in different sets of holes, raised it 2 sets of holes. It doesn't pull as much to the right, a slight reduction. But there is a lot of cavitation coming out of the hole. And even in calm water the boat bounces steadily as if I were hitting waves. Would a set of those stabilizers such as something from this Cabela's online catalog help me out?

http://www.cabelas.com/cabelas/en/t...netcon&parentType=index&indexId=cat21370&rid=

 

[cougar1985]

Re: Motor INSISTS On Veering To Starboard!

if everything has been tried ,could you have a damaged hull?i had a older boat that was a problem and it turned out to be a hook in the hull that was giving me fits.id recomend the nauticas trim tabs over the cavatation plate style any day.my last glass boat was uncontrolable at high speed until i put them on then it was good.

 

[Kiggsia]

Re: Motor INSISTS On Veering To Starboard!

No hook or other hull damage but I'll check into those trim tabs, thanks.

 

[Kiggsia]

Re: Motor INSISTS On Veering To Starboard!

Cougar 1985, just what type of handling problems did you have? I haveno problem getting on a plane, just the constant pull to the right and the cavitation as I adjusted motor tilt to keep the bow from riding too low, in case bow steer is my problem.

 

[Kiggsia]

Re: Motor INSISTS On Veering To Starboard!

The trim tab being adjusted to the right, when the engine is moving forward, results in the trim tab being forced to a straight ahead position.

As such, this would result in the trim tab forcing the engine into a left turn position. Draw it out on a piece of paper, you'll see what I describe.

Joe , the reason I can't get this through my head is that if I wanted to make a left turn, I would of course pull the motor tiller to the right, which of course would cause the rear of the skeg rudder to go to the left, rotating the boat to the left, yet if the (rear of?) the trim tab we're discussing is turned to the right the boat would rotate slightly to the left? I can't see how the action of this small trim tab could work opposite of the action of the skeg rudder? I am not disagreeing with what you are saying, I think I don't quite understand what you've told me!

 

[Joe Reeves]

Re: Motor INSISTS On Veering To Starboard!

The trim tab issue also holds true with aircraft. Adjusting the small trim tab of the larger elevator (horizontal tail surface) forces the trim tab to move the larger surface.

Moving the boat engine's trim tab to the right results in the waters motion over that tab to force the tab straight in line with the boat's direction of travel. This results in having the engine turn slightly off center,causing the boat to turn in the opposite (left) direction.

Perhaps I'm unable to explain it properly but that's the way it works. If I should come across a texted/published explanation, I'll pass it along.

 

[crxess]

Re: Motor INSISTS On Veering To Starboard!

Silly question? Have you tried sitting opposite and steering with the other hand?

When sitting static in the water, in driving position, is the boat setting level or leaning to one side?

Even my 22' Sea Ray will pull to one side if people/weight is offset.

Boats hull is like the wing on a plane. more of one side in water will increase drag on that side while reducing drag on the opposite side - doubling the effect.

Is the motor true to the vertical center line of the hull?

 

[Kiggsia]

Re: Motor INSISTS On Veering To Starboard!

Joe, when you say "move the boat engine's trim tab to the right", you do mean the REAR (trailing edge) of the trim tab, right?


The motor seems centered, and the boat was balanced. If the motor is not perfectly centered, I'm stuck with it as it is of course, bolted down.

 

[crxess]

Re: Motor INSISTS On Veering To Starboard!

Kiggsia, does your 40 have an adjustable steering collar? i.e. is your steering extremely easy in neutral? You should be able to snug it up to help reduce prop twist transmitted back to the tiller. I believe it is a screw that applies pressure on the thrust ring or upper collar.
This is a trolling adjustment on my 6hp to keep it straight with minimal user input.

 

[Joe Reeves]

Re: Motor INSISTS On Veering To Starboard!

Kigg.... Yes, when I say move it to the right, I am speaking of the rear portion of the trim tab, the portion that hangs down.

 

[Kiggsia]

Re: Motor INSISTS On Veering To Starboard!

There is a bolthead sticking out of the area where the motor hinges on the transom, I'll tighten that and see if it helps any. It steers easy in neutral but I don't know if it is too loose.......I took a closer look at the skeg today and it looked like it might have been bent just a very small amount to the right. I tapped on it with a piece of wood and a hammer and it seems straighter now. Don't know if it was bent enough to matter or if I was able to help it much. I hope to run the boat tomorrow if it's not too chilly here in Toledo Ohio where the weather is unseasonably cool.
Thanks for all the advise, gentlemen.