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Author Topic:   New Motor Steering Adjustment
hauptjm posted 10-01-2012 05:53 PM ET (US)   Profile for hauptjm  
I recently purchased a new 150hp ETEC for my 18 Outrage. I've run it several times and had to adjust the steering tab on the lower unit as it pulled considerably to the right. The factory had it set dead center.

Although I've moved (albeit slightly) it a few times to compensate for the "pull" to the right, I'm still no where near at a point that feels safe. At higher speeds it really pulls. Any suggestions or do I continue to move it to compensate?

Notation: I removed a fixed Armstrong bracket and replaced it with a 12 inch set-back hydraulic jack-plate. The height at which the motor operates totally changes the operating variables. Ex: maneuverability at slow speeds requires dropping the motor vertically. It is a learning process, but the options available in engine trim are huge.

Jefecinco posted 10-01-2012 07:07 PM ET (US)     Profile for Jefecinco  Send Email to Jefecinco     
I hope my old memory is working correctly this evening.

The tab adjustment is counter-intuitive. If the boat pulls to the right the tab should be adjusted as if it was a small rudder set to turn to the right.

This has the effect of pushing the after part of the outboard to the left which, in turn, causes the engine to steer slightly to the left thus offsetting the existing tendency to steer to the right.

I'm sure that could be stated much more clearly by someone much less tired.

Butch

L H G posted 10-01-2012 07:46 PM ET (US)     Profile for L H G    
Jim - As you know, I run a single, jackplate installed, small bore 150 Mercury on my Outrage 19, with trim tab anode set straight and Laser II performance prop. Top speed is probably similar to yours, about 47 MPH. I have original and standard Big-T steering, which transmits propeller torque to the wheel.

Most here will disagree with me, but for a contrarian report, here is mine. Because of the way I use the power trim, the boat steers incredibly easy, with no pull at under most running conditions, and rock solid at WOT. Mercury's published operating advice is simple: "Once underway, at any speed, trim engine out until steeering pull is equal in both directions. This is optimum position for both economy and speed." I'm paraphrasing, but that is basically what they say.

At higher speed, the steering torque can reverse, and you have to trim in to avoid pull in the opposite direction.

If I install a Mercury Enertia prop, I have to remove the trim tab altogether in favor of a flat plate anode, so this technique is the ONLY method anyway.

I would set your tab straight, and try Mercury's advice, and see if it works for you.

I have noticed that Mercury's lower units use a completely different hydrodynamic shape and trim tab than the old OMC units being installed by Evinrude, so maybe there is some differing performance implication with merc's lower unit. If that is the case, I can't offer any advice.

Incidentally, I would recommend either a Mercury Laser II (if you can turn 19" of pitch) or Enertia prop for your rig.

Show us some photos. I'm anxious to see a full transom 18 with a jackplate. I had recommended that same installation to someone a few years ago, but never saw or heard how it turned out.

Tom W Clark posted 10-01-2012 08:07 PM ET (US)     Profile for Tom W Clark  Send Email to Tom W Clark     
What Mercury actually says is (and I quote from my Mercury Owner's Manual here):

"Propeller torque at higher speeds can cause steering pull. That pull can be partially offset by adjusting outboard trim, but changing trim tab position is preferred."

sosmerc posted 10-02-2012 12:51 AM ET (US)     Profile for sosmerc  Send Email to sosmerc     
You should also be aware that a "torque tab" can be added to the skeg to offset torque steer at engine heights where the trim tab is actually above the surface at high speed. For example, Mercury High Performance gearcases are available with built in torque tabs on the skeg.
Peter posted 10-02-2012 07:07 AM ET (US)     Profile for Peter  Send Email to Peter     
"I have noticed that Mercury's lower units use a completely different hydrodynamic shape and trim tab than the old OMC units being installed by Evinrude..." (LHG - emphasis added).

What "old OMC units" are you referring to? It seems by that comment that you are completely unaware that a current Evinrude 150 E-TEC comes with a Magnum SLE gearcase, a gearcase that did not exist during the OMC era. Prior to that, Evinrude 150 E-TECs came with the first generation Magnum in which the leading edge of the gearcase had a forward lean to it. Evinrude 150 E-TECs never came with the Offshore (O-type) gearcase, the gearcase that was used on V6 outboards during the OMC era.

Tom W Clark posted 10-02-2012 10:25 AM ET (US)     Profile for Tom W Clark  Send Email to Tom W Clark     
Jim -- Yes, you continue to move the trailing edge of the trim tab to starboard until the steering effort is neutral at the cruising speed and trim you most commonly use.

I'm surprised you do not have hydraulic steering. Rigging a dual mechanical cable steering system for a motor on a bracket is rather awkward.

L H G posted 10-02-2012 04:46 PM ET (US)     Profile for L H G    
Sorry for the confusion Peter. This discussion is about trim tabs, not gearcases, and in looking at my post, I see I missed omitting the "and" in the first line as I edited. All of the Evinrude trim tabs I have seen over the last 30 years are rather thick looking, more like a lever handle. They are very different in appearance to the thin Mercury trim tab, so I thought that could make a difference in steering torque correction, for better or worse, I don't know.

But as know, I only consider a trim tab as an anode. If I had an Evinrude, I would set it straight also, since I have too many variable running and trimming situations.

Tom W Clark posted 10-03-2012 10:49 AM ET (US)     Profile for Tom W Clark  Send Email to Tom W Clark     
The trim tabs of the Mercury and OPMC/BRP motors differ slightly in design but are about the same thickness; the Mercury tab actually has a greater maximum thickness.

Larry -- I'm surprised that after all these years of boat ownership, you never figured out how correctly set up and operate your outboards. This might explain why all the photos of your boats running show the motors tucked in so far, like a dog with its tail between its legs.

You should take the advice offered by Mercury, Boston Whaler, Evinrude, Yamaha, Honda, Suzuki and Tohatsu and adjust your trim tabs. If it is was meant to simply be set straight, it wouldn't be adjustable, now would it?

Tom W Clark posted 10-03-2012 11:02 AM ET (US)     Profile for Tom W Clark  Send Email to Tom W Clark     
For those who have not read their Boston Whaler Owner's Manual:

http://continuouswave.com/whaler/reference/manual18-25/operations. html#trimTab

L H G posted 10-03-2012 12:36 PM ET (US)     Profile for L H G    
Come on, Tom, get off your high horse. As a supposed prop guy and engine height expert, you should know better. On three of my five Whalers, I can't even run trim tabs because of high raked Mercury props, and have to use flat plate anodes. Four of them have hydraulic steering. One uses counter rotating Revolution-4 props where tabs would always be set straight ahead anyway, even if those engines could use them in the first place. All have engines running at least 1-1/2 above the water flow off the transom, leaving any trim tabs on the remaining two boats with no effect whatoever.

I have one boat with heavy duty Big-T mechanical steering, 150 HP Merc running 2" high on a jackplate. Here agin, no trim tab effect at all. And whem I get around to putting a high rake Enertia prop on it, the trim tabe will have to be removed on that one also. Proper engine trim at any given speed is what works on the one mechanical steering boat where I can experience any pull at all.

That Whaler reference you make is old news from the 80's.

hauptjm posted 10-03-2012 02:12 PM ET (US)     Profile for hauptjm    
Thanks for the replies!

I'll continue to adjust the tab as directed and see where that gets me. Part of the uniqueness in this setup is how totally different the boat's "attitude" is with even very slight adjustments in motor height utilizing the hydraulic jackplate.

Tom, I do have hydraulic steering. With that said, I still get quite a pull to starboard. I'll find the sweet spot!

Larry, when I get some time, I'll shoot a few pictures. It's really a great setup.

Tom W Clark posted 10-04-2012 01:02 AM ET (US)     Profile for Tom W Clark  Send Email to Tom W Clark     
Larry -- As Mercury's Number One Cheerleader, I am surprised you remain so ignorant of the products they offer.

Just substitute the 82277Q 1 Trim Tab ("For applications where the extra clearance is required for high rake propellers.") for the 3164Q 4 Trim Tab you have now and away you go with the Enertia or the Revolution 4.

Interestingly, I have yet to encounter a clearance problem on any OMC or BRP outboard motor with any high rake propeller.

You are correct, however, about twin counter-rotating outboards not requiring trim tabs at all. The steering torque of each counteracts the other resulting in mostly neutral steering forces at the helm.

However, if you start reading at the top of this thread you will realize we are not talking about a twin counter-rotating Whaler, but Jim Haupt's Outrage 18 with a single 150 that he is trying to quell the steering torque of.

Tom W Clark posted 10-04-2012 01:05 AM ET (US)     Profile for Tom W Clark  Send Email to Tom W Clark     
Jim -- I presume you mean that you feel great resistance to turning the wheel to port and not actually a pull to starboard. Hydraulic steering systems do not allow the motor to pull the wheel at all unless something is wrong with it, but you can certainly feel added resistance in one direction versus the other if your trim tab is not adjusted correctly.
hauptjm posted 10-08-2012 01:52 PM ET (US)     Profile for hauptjm    
Tom,

I actually have a real pull to starboard. If I remove my hand from the wheel at speed, I'm going to starboard - hard!

Since, this is the first time I'm replacing the motor on this hull, this is new to me with regard to the pull. My previous motor didn't pull at all. It's the same Sea Star system that controlled the old motor and nothing seems out of the ordinary.

I did have to disassemble the steering to remove the center console and deck when I replaced the internal tank, but the engine dealer reinstalled it when they installed the new motor. There is no leaks and it retains fluid and moves the engine just as well as before. The one difference is this strong pull to starboard at speed.

I haven't been able to play with it since originally posting as I'm chasing a kid around the country sailing an Optimist, but will reinspect the entire system.

You state that the system should not allow a "pull" to starboard, but rather a resistence to port. What should I be looking for on inspection? As I stated, I certainly don't see any indication of a leak.

Jim

Whalrman posted 10-08-2012 03:34 PM ET (US)     Profile for Whalrman  Send Email to Whalrman     
You had to remove the steering to take the console out,correct? I'll bet the steering system needs to be bled some more to get the rest of the air out because, as Tom said, it should do what you're saying it's doing.
Tom W Clark posted 10-09-2012 10:07 AM ET (US)     Profile for Tom W Clark  Send Email to Tom W Clark     
Jim -- You're say that if you let go of the steering wheel, the wheel will spin?

That is not right and means a check valve in the helm is malfunctioning.

hauptjm posted 10-09-2012 03:48 PM ET (US)     Profile for hauptjm    
quote:
Jim -- You're say that if you let go of the steering wheel, the wheel will spin?

That's exactly what I'm saying! When you refer to the check valve are you referring to the Relief Valve? Are these accessible? And if so, how?

When I look at the exploded illustration of the helm pump, I don't even see them referenced. Further down in the spec sheet of the manual, there is mention of the Relief Valve being 1000psi(68 bar) at the helm pump. Draining the system should not damage these valves, so I'm confused how it would have happened.

Whalrman posted 10-09-2012 04:17 PM ET (US)     Profile for Whalrman  Send Email to Whalrman     
Ment to say ..."it shouldn't do what....." May have a piece of debris in it from the removal or reinstall.
Tom W Clark posted 10-10-2012 11:15 AM ET (US)     Profile for Tom W Clark  Send Email to Tom W Clark     
Jim -- I'd call Teleflex Marine Customer Service and describe the behavior of your steering system. That is not right; the SeaStar (like all hydraulic systems) is a no-feedback (NFB) steering system.
sosmerc posted 10-10-2012 11:29 AM ET (US)     Profile for sosmerc  Send Email to sosmerc     
I concur that there is something wrong with the steering system. There could be debris in the system somewhere that is letting fluid leak by an o-ring or check valve...it could even be in the cylinder itself.
I once had a brand new system with a problem in the cylinder...in order to maintain a straight line I had to be continuously turning the wheel to port...that was a fun one.
Teleflex replaced the front-mount cylinder without any questions. They are a good company to deal with.
hauptjm posted 10-22-2012 11:11 AM ET (US)     Profile for hauptjm    
At this point, I'm in touch with Customer Service at Teleflex. The most recent reply stated the helm pump is "shot" and needs replacement. I have an inquiry in to determine if the helm can be rebuilt or in fact has to be replaced (and which is most cost effective).

I have to say, the customer service department of Teleflex is very responsive and timely. I'm impressed!

hauptjm posted 10-22-2012 11:14 AM ET (US)     Profile for hauptjm    
Wow! Just heard back from Teleflex (they are fast). Helm should be replaced not repaired. All things being equal, it sounds like more of a safety concern than anything else. I'll follow their recommendation!

Thanks for the comments.

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