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Author Topic:   Montauk leveling problems
Andre C posted 01-21-2004 10:22 PM ET (US)   Profile for Andre C   Send Email to Andre C  
I have a Montauk 17 that leans to the port side while underway. The faster I go the more the lean. I tried shifting the weight around ie. batteries and livewell and found no change. Is this a typical Montauk characteristic? Any help would be appreciated.
JohnJ80 posted 01-21-2004 10:43 PM ET (US)     Profile for JohnJ80  Send Email to JohnJ80     
don't know for sure, but i bet this is due to prop torque. is it affected by trimming the motor up at all? is this happening with your motor all the way down?

J

Andre C posted 01-21-2004 10:47 PM ET (US)     Profile for Andre C  Send Email to Andre C     
It gets better when trimming up until the porposing starts. Should I start by trying to adjust the torque fin on the lower unit?
Tom W Clark posted 01-22-2004 12:28 AM ET (US)     Profile for Tom W Clark  Send Email to Tom W Clark     
Andre,

Yes, this is typical Montauk behavior. As John points out, it is caused by the propellor torque of the outboard motor. There have been detailed explanations of this phenomena here that you can search out with the search engine, but suffice it to say that adjusting the weight distribution will be your best method of keeping an even keel while under way.

The trim tab on the outboard's lower unit can affect the list of your boat. It is important that it be trimmed so that the steering feedback is neutral when the motor is trimmed to it normal angle of trim.

If you have a No-Feed-Back steering system, it is entirely possible the trim tab is significantly out of whack and may be exacerbating the list you are experiencing.

Andre C posted 01-22-2004 08:50 AM ET (US)     Profile for Andre C  Send Email to Andre C     
The trim fin is set at the 0 position. I will try some experimentation this weekend. I do have the no feedback steering.
Bigshot posted 01-22-2004 11:19 AM ET (US)     Profile for Bigshot  Send Email to Bigshot     
If torquing to the right you want to move it clockwise(left). If the tab is in the 6 o'clock position, try the 7, not the 5.
JayR posted 01-22-2004 12:01 PM ET (US)     Profile for JayR  Send Email to JayR     
I tried numerous times to remedy this problem to no avail...
Went so far as to purchase and install the trim fins on the hydrofoil. That too was ineffective.

A back injury has left me with one leg in spasm (sciatica). Now, the only place I can stand up straight is in that boat while on plane :-).

It was my observation that surgically shortening ones leg to be an easier fix... ;-)

JohnJ80 posted 01-22-2004 03:12 PM ET (US)     Profile for JohnJ80  Send Email to JohnJ80     
I think you want to adjust the torque fin at the appropriate trim setting for a mid range speed. Most outboard trim units can actually trim the motor in a few degrees farther than would be a neutral setting.

When my motor is all the way in, steering is hard and it has a tendency to do exactly as you describe. I find that when I trim out to the point the NFB steering is neutral (the internal clutch is not engaged), then that boat tracks well, the steering is easier and the list is gone.

So, I would find that trim spot carefully, then go adjust at that point (or at least evaluate your torque fin adjustment at that point).

J

John W posted 01-22-2004 09:28 PM ET (US)     Profile for John W  Send Email to John W     
You are definitely dealing with prop torque. All single engine boats face this to one degree or another, but if it's a pronounced heel to port, something's not quite right. Try adjusting the trim angle and also the little trim tab on the motor as others have suggested, but if that doesn't help, you may need to try a different propeller.

A four bladed propeller will produce less prop torque than a 3 blade prop will. I had a pretty noticeable heel to port at speed on a Mako I used to own, and a 4 blade prop eliminated it. Trying different props (even different 3 blade props) will make a difference as to how much heel to port you're dealing with.

The final solution if all else fails are hydraulic trim tabs.

Sal DiMercurio posted 01-22-2004 10:13 PM ET (US)     Profile for Sal DiMercurio  Send Email to Sal DiMercurio     
The main function of the trim tab is not trimming the boat because it leans to one side.
The main function is to correct the steering if it pulls [ not leans ] to one side.
If you let go of the wheel & it immediatly wants to pull the boat to the port, [ not lean to port ] then the tab needs to be turned very slightly in the direction the boat is pulling to.
You can adjust that tab all you want & it wont cure a lean, but it will stop the wheel from pulling in one direction.
Theres a difference between leaning to port & pulling to port, the trim tab corrects the pull, but not the lean.
Sal
jimh posted 01-23-2004 03:54 AM ET (US)     Profile for jimh  Send Email to jimh     
Also see this previous discussion on the topic:

Montauk list to port
http://continuouswave.com/ubb/Forum4/HTML/000380.html

Andre C posted 01-24-2004 10:21 PM ET (US)     Profile for Andre C  Send Email to Andre C     
The trim fin adjustment did the trick! Thanks guys!
JayR posted 01-25-2004 12:09 PM ET (US)     Profile for JayR  Send Email to JayR     
What do you have to say to that Sal???

Go figure...

Andre C posted 01-25-2004 05:09 PM ET (US)     Profile for Andre C  Send Email to Andre C     
I'm getting 44 MPH according to the GPS @ 5500 rpm trimmed up. Running a 90hp Johnsonrude 2 stroke. Propped with a Viper 13 3/8 17p. I'm not complaining.
Sal DiMercurio posted 01-25-2004 06:07 PM ET (US)     Profile for Sal DiMercurio  Send Email to Sal DiMercurio     
Jay, i'd say he had a pulling problem, as all outboard boats have a little or alot of torque lean.
He has nfb steering so he couldn't tell if it was pulling or not.
Theres a difference between pulling & torque lean.
If he didn't have nfb steering & let go of the steering wheel, he would have gone around in circles immedietly
Sal
Andre C posted 01-25-2004 06:50 PM ET (US)     Profile for Andre C  Send Email to Andre C     
Even with the NFB steering you can feel torque pull when you move the wheel underway. The wheel does not move with the pull, but you can feel it when you steer either way. Lets be cordial here. We're all trying to help!
Tom W Clark posted 01-25-2004 07:17 PM ET (US)     Profile for Tom W Clark  Send Email to Tom W Clark     
Andre,

I'm glad you've worked out your list problem. Your boat is no slow poke either, now is it?

Jason,

I'm not sure your comments were necessary. Most of what Sal says is absolutely true:

The main function of the trim tab is not trimming the boat because it leans to one side. Yes, this is correct and undisputed.

The main function (of the trim tab) is to correct the steering if it pulls, not leans, to one side. Again, true and undisputed.

If you let go of the wheel & it immediatly wants to pull the boat to the port, not lean to port, then the tab needs to be turned very slightly in the direction the boat is pulling to. Well, this is true also.

You can adjust that tab all you want & it wont cure a lean, but it will stop the wheel from pulling in one direction. Now we have a disagreement. This statement is only partially true, and in fact, has been disproved by Andre's own recent experience.

The fact is that while the trim tab is there to correct a steering pull caused by the outboard, it can and does have an effect on how the boat lists while running under power.

Theres a difference between leaning to port & pulling to port, the trim tab corrects the pull, but not the lean. Again, only partially correct. The reality is that having a trim tab out of adjustment not only affects the steering, it can also affect the degree to which a boat like this can list. Here's how:

We all know that when you make a turn in an outboard powered runabout like a Montauk, the boat leans into the turn (assuming the boat is running on plane). Why does this happen? It is primarily because the thrust from the outboard is no longer aligned with the keel, it is angled to one side or the other so this lateral component of thrust pushed the lower unit of the outboard to one side and the reaction of the hull to to lean away from this lateral thrust.

We also know that a Montauk will tend to run with a list to port caused by propellor torque. For a detailed explanation of this phenomena see:
http://continuouswave.com/ubb/Forum4/HTML/000351.html
If the trim tab is significantly out of adjustment it will try to "steer" the outboard to one side or the other and thus there will be slight lateral element of thrust that, is it is to port, will exacerbate the list caused by the propellor torque.

I agree with Sal that adjusting the trim tab will not necessarily solve a list to port but it certainly can reduce it if the tab is out of whack. It's a secondary effect of the tim tab, not what it is there for, but very real none the less.

Now we can argue all we want about physics, theory and all that, but I have owned two Montauks powered by Johnson 90s and can attest to the fact they will tend to list to port and that's just part of the deal. Adjusting the weight distribution in the boat is the first and foremost thing one can do to try to maintain and even keel, but if you have a NFB steering system, you still need to adjust the tim tab on your outboard for neutral steering pull.

If anybody doesn't believe that the trim tab can have an effect on how a Montauk lists while under way, I suggest you go throw your trim tab out of whack, run the boat and then come back here and tell us how it ran.

Andre C posted 01-25-2004 08:19 PM ET (US)     Profile for Andre C  Send Email to Andre C     
Amen brother! Just another problem solved. Glad I didn't have to buy another prop. I just bought the boat virtually new. (18 hours) Its a 1998 model sold new in 2000 and garage kept. I paid $11k and thought it was a bargan. I wanted the classic montauk and not the new 170.
I am very happy with my purchase. If anyone has a site to link up pictures I'll show it off.
Andre C posted 01-25-2004 09:53 PM ET (US)     Profile for Andre C  Send Email to Andre C     
Another thing. This boat must have been rigged by a whaler dealer and... The trolling motor and battery was rigged on the port side. The transducer for the depth finder was rigged on the starboard side. Can we make matters worse? Just thought a whaler dealer would have known....

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