Outboard Motor, Tilt&Trim and boat performance

WyattEarp · September 03, 2019, 10:26:59 PM

So, I have a Nitro 640lx, 60HP with tilt and trim.
A few questions from a novice -

With the outboard running at about full throttle - The boat seems to lean a bit to the left, I am being told that you can correct this by trimming the motor either up or down.
Can anyone confirm this?

Secondly, the motor, which I figured would have a steel rod/ stainless rod on the outboard motor support so that when the motor is trimmed all the way down, it goes down to the same place every time. This motor mount is drilled, but no rods are in place? so the motor is trimmed down to the transom basically. I remember my father in laws old Monarch boat which did have a tilt and trim, but there was a rod that went through the mount to stop the motor at that location.

Hope that makes since....

Ron Fogelson · September 03, 2019, 10:55:04 PM

Yes adjusting trim will not only level your boat but also make it easier or harder to turn.

Start trimmed all the way down and hit the gas, once you go wide open then start trimming up to see/feel how the boat acts, pay attention to how high you have to trim it to get max speed, how high to gain the best handling and then you can adjust the trim as you take off and slow down to help stay on plane best. I would not offer this recommendation with higher HP motors but as you stated your new and with the low HP you will be fine just remember if the boat starts to feel like its getting away, pull back on the gas.

As far as the rod those are on smaller older motors, its there to set the trim in the best plane and running position because there isn't a tilt trim on the motor. Basically they set it and that's it yours you trim all the way down to take off then trim up as needed to best match your throttle speed

WyattEarp · September 04, 2019, 01:29:07 PM

Thanks Ron.
I had one of the rods on my old 9.9, but the father in laws boat was around 75 maybe 80 HP and his had the rod as well.
I will try your suggestions next time I take it out

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WyattEarp · January 27, 2020, 05:51:26 AM

I have had this boat for a few months now and had it on the water many times.
I am by no means an experienced boater, but I have learned a few things while navigating this small boat.
I can maintain this boat to a certain extent but I do not think the set up is correct, the boat is very uncontrollable, it has a serious lean that can somewhat be corrected with the trim, but even then the boat is not stable. I recently added a hydrofoil to the motor because I was told it would help with the leaning and stability once on plane, but this thing had a negative impact on the boat. It would get on plane much faster, but once on plane the leaning was much worse and trim had no effect on it.

I am looking for suggestions on how to correct this problem, before I throw my hands up and go to another boat.
The outboard is a 60hp, it is mounted on the upper most holes on the mount, but the cavitation plate appears to be even with the bottom of the boat. I would raise the motor if I thought it would help.
I am not sure the pitch of the prop but it is 3 blade, I would assume it is the OEM prop.

Before the hydrofoil was installed I had a slight lean to the right which I could correct via the trim, but the boat was still hard to control and seemed unstable. After adding the hydrofoil, the lean was to the left and severe to the point that it was scary. The trim tab on the outboard is fairly close to mid position and maybe adjusting that would help ?

Any suggestions appreciated.

Mike Cork · January 27, 2020, 02:53:13 PM

Something is really not jiving. The Dolphin Tail should never make it worse. Starting to wonder if you don't have some de-lamination on the bottom of the boat causing issues.

There is a possibility that the motor is too high. We always raise them to get more speed and performance out of them but there is a point when the motor is so high that it can't hold the noise of the boat. This creates a very squirrely situation.

Maybe try lowering the motor and see happens.

Most boats run 2-4 inches below pad. Meaning the cavitation plate sits 2-4 inches below the bottom of the hull. Super light boats like bullets or Allisons can run at or above pad.

Bud Kennedy · January 27, 2020, 03:06:25 PM

Just wondering if it could be the low unit trim tab adjustment?

WyattEarp · January 27, 2020, 03:13:26 PM

The motor is sitting as low as it can possibly be mounted without adding a jack plate.

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WyattEarp · January 27, 2020, 03:17:03 PM

Side view

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Mike Cork · January 27, 2020, 03:41:04 PM

I miss typed before, it's the prop shaft that's measured, not the capitation plate... Sorry about that.

Looking at your photos the motor mount looks fine.

I'd look closely at the transom mounts and make sure everything is solid, and I'd climb under it and look around as best you can.

What year is the boat? Not to start any issues but I know if two nitro's that have had serious separation issues. Your leaning issues, especially since they are changing from side to side, make me wonder if you don't have a stringer separation issue.

Bud Kennedy · January 27, 2020, 04:00:38 PM

Here is the process to measure prop to pad.

WyattEarp · January 27, 2020, 04:45:31 PM

The Nitro is an 06 model.

Before the hydrofoil, the lean was minimal to the right, I was able to correct it with the trim.
With the hydrofoil, the trim made no difference whatever.
The trim tab just above the prop was turned a bit more before I added the fin, but I thought this was only there to help adjust the steering tension one way or the other, would it also have an affect on the lean?

Princeton_Man · January 27, 2020, 07:36:54 PM

Quote from: Bud Kennedy on January 27, 2020, 03:06:25 PM
Just wondering if it could be the low unit trim tab adjustment?

I think you're right Bud. The trim tab appears straight in that picture.

Bud Kennedy · January 27, 2020, 08:19:26 PM

Quote from: WyattEarp on January 27, 2020, 04:45:31 PM
The Nitro is an 06 model.

Before the hydrofoil, the lean was minimal to the right, I was able to correct it with the trim.
With the hydrofoil, the trim made no difference whatever.
The trim tab just above the prop was turned a bit more before I added the fin, but I thought this was only there to help adjust the steering tension one way or the other, would it also have an affect on the lean?

I think it is possible as a contributor to the condition. Kinda hard to explain without actually feeling it myself. I still believe also that your boat is a wee bit under powered. Your HP is within the recommendation for motor power but on the low side. I think your max hp rating for that boat is 90 HP. So couple the motor power with what appears to be a too deep motor height you might be able to improve the overall performance. It kinda depends upon what your actual Prop to Pad measurement turns out to be.

Do I remember correctly that at some point along the way, did you mentioned that you are a pretty big guy? Weight distribution might have an impact on what you describe as lean. especially for a small boat like yours.

WyattEarp · January 28, 2020, 03:46:25 PM

Define big -
I am 6'2" 225lbs.
So not oversized, but I carry some weight.
What is odd to me, the reason I installed the fin was simply to help get on plane a little faster and it does that. If that little trim tab on the outboard has that much affect on the lean I would be surprised.
But I will move it next time out and see what happens.

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Princeton_Man · January 28, 2020, 06:12:25 PM

The trim tab will control torque on the wheel, not too sure having any effect on the lean and since the lean is to the port/left side, I doubt the operator's weight would have any influence that would make it lean left. How does it set in the water?

Bud Kennedy · January 28, 2020, 06:14:48 PM

Quote from: WyattEarp on January 28, 2020, 03:46:25 PM
Define big -
I am 6'2" 225lbs.
So not oversized, but I carry some weight.
What is odd to me, the reason I installed the fin was simply to help get on plane a little faster and it does that. If that little trim tab on the outboard has that much affect on the lean I would be surprised.
But I will move it next time out and see what happens.

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Nope, you must not be the guy. Someone a while back with a similar question stated he was 6'5" and weighed 350 Lb. So, no, I would not put you anywhere near that category.

Oldfart9999 · January 29, 2020, 08:48:38 AM

try putting the trim tab back to where you saw it then try it. Try moving it one notch away from center then and see if that helps. Also, check and make sure the transom is solid, if it moves when you turn the motor by hand or you lift the lower unit get another boat, the transom need to be replaced and you really don't want to do it or pay to have it done.
Rodney

WyattEarp · January 29, 2020, 02:50:12 PM

The transom on this boat is solid as a rock. The boat is in great shape other than this problem.

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Bud Kennedy · January 29, 2020, 03:48:30 PM

Running out of ideas. Lets ask a couople more questions. With the boat sitting in the water without the motor running, does it Lean? Or is it only when you are underway, under power. Does it happen at Idle speed or on plane.

What I am leading to is a torque effect deal and to assess just how much does the boat Lean Still very curious about what your prop to pad measurement is and what is the pitch of the prop you are using. If it only happens when on plane or going on plane what rpms are you making?

Please forgive my line of questioning, I am just trying to get a mental picture of what you are dealing with. I am now suspicious of how much lift you are getting from your overall set up with regards to proper motor height an/or prop selection. If as you say the boat is in great shape then I would assume something is amiss with the total overall set up.

WyattEarp · January 29, 2020, 09:45:29 PM

Quote from: Bud Kennedy on January 29, 2020, 03:48:30 PM
Running out of ideas. Lets ask a couople more questions. With the boat sitting in the water without the motor running, does it Lean? Or is it only when you are underway, under power. Does it happen at Idle speed or on plane.

What I am leading to is a torque effect deal and to assess just how much does the boat Lean Still very curious about what your prop to pad measurement is and what is the pitch of the prop you are using. If it only happens when on plane or going on plane what rpms are you making?

Please forgive my line of questioning, I am just trying to get a mental picture of what you are dealing with. I am now suspicious of how much lift you are getting from your overall set up with regards to proper motor height an/or prop selection. If as you say the boat is in great shape then I would assume something is amiss with the total overall set up.

Bud

Sitting idle the boat seem pretty level - with the exception of a slight lean to the driver side, I assume this is my big butt that causes this and it only slight.
Before adding the hydrofoil when coming up on plane the boat still had a lean to the right, I could trim up just a bit and it leveled out but seemed to drift a bit and took a good while to get on plane with this motor.

I added the hydrofoil to help get on plane faster and I assumed it would also help stabilize the boat once on plane. Getting on plane much faster now, but just as soon as you have any speed on the boat it starts the lean - now to the passenger side which should be the lighter side of the boat when I am alone, the faster you go the more it leans until it gets scary and I get out of it, the max speed on this boat with the 60HP is probably only around 30 if that - so I am not going fast by any means.
Trimming with the hydrofoil has no effect on the lean at all.

I took a straight edge and came off of the bottom of the boat to the hydrofoil to check and see if it was level with the boat and I could not get 1/16 difference from side to side, it was probably within 1/32.

I am considering trim tabs, but I dont want to just keep throwing money at it not knowing the cause, if I can find the cause I can find the cure.

Thanks to everyone for their suggestions, should be a nice day Sunday to try to figure it out

Bud Kennedy · January 30, 2020, 08:03:53 AM

Wyatt, it is beginning to look like it is just the nature of the beast so to speak. Might have to be something you will just have to deal with. Certainly something is not right but who know what it might be. I still encourage you to perform the prop to pad measurement. and it may just help to understand why the craft is falling off the pad.

Wizard · February 02, 2020, 01:42:22 PM

Not being an ass but if you carry a lot of gear in a boat and don't balance the gear both forward/rear AND right/ left, you can put ride and control problems into a boat. I've had 17 bass boats from a Star 14' fiberglass/40 hp Merc to a BassCat Puma 20.5' with a 225 Merc. With a tournament load, I balance even the Puma. You have a smaller boat with a 60 hp. The big adjustments such as motor height or prop change are the first things we think of when doing adjustments. Often the small adjustments solve the problem.
I had a guy ask me to look over his boat at a derby because it had a lean to it. I looked at his load balance, trim tab, everything I could think of without success. Finally, I looked up and the problem was right in my face. The owner weighed in at 280 lbs. and his partner had the nickname of "Stringbean".

Wizard

WyattEarp · June 16, 2020, 09:20:37 PM

So its been nearly a year since I bought this boat - or should I say started making payments on this boat...... I am on the water nearly every weekend rain is not in the forecast and some weekdays, now that we have longer days.
I think I have figured this problem out although I still believe the motor could be lifted a little..

I trim all the way down and throttle up - the boat begins to lean at around 3000 rpm, I start trimming up at that point and throttle on up to around 4000 and the boat levels out and runs straight.

Guess I just needed to some experience in the boat, although it is totally different with a passenger.
Still learning

Deadeye · June 17, 2020, 07:55:50 AM

That boat is about the Time when they were starting to switch over to the Z-6,7,8 Models.

I was looking at a Z-6 Model at one point that was one of the earlier models. What I found by doing Research was that There were Several Years that the early Models of Z-6 and the Comparable Models that had a Severe Lean Issue. At first it was Denied by the Manufacture but there were so many Owners that reported the exact same issue that they had to address it.

I do not know of any "fix" for the Lean that I was ever able to find, and that was the very reason I passed on several otherwise very nice looking Boats with ow hours on with a great prices, I simply did not want to take the Chance of being one of the ones that got a "leaner".

Just To Be Sure, this is NOT a slam on Nitro by any means. Today thy make IMO an awesome boat. But they did have some documented issues with certain models in the past.

All I can suggest to you is to do some research on your Model and read what the Forum Hits have to say about it. You may find the answer you are looking for. Good Luck.