Propeller problem or Trim tab problem? 2001 90HP

Hello all,

I was wondering if someone could enlighten me on a little issue I'm having with my boat and port steering.

My boat is a Flare 1981 with a 2001 Mercury 90HP, engine is in great working condition, I recently took it out for a spin after a few years on the bench and the boat leans to port side as you gain speed. My questions arise from this point on, the boat literally after probably 12-14 knots goes on a steering frenzy where I have to pull as hard as I can on the wheel for it not to go completely port, the boat itself lifts its starboard side 20>30 degrees while still managing to go somewhat straight (me pulling on the wheel), regardless to say this is a pretty dangerous stunt i'd like to avoid repeating.
So:
- Is it a propeller issue? When I bought this boat, the old man who owned it gave me an aluminum 3 blade propeller he had laying around from his other boat, specifically said that it did not belong to this boat, however to me it is neither too big not too small. I'm wondering if maybe the pitch or the entire propeller setup is wrong, I cannot even get to full rpms since at 14 knots I'm pretty much doing a Captain Morgan kind of stance. Buddy of mine swears this is my problem and that I should take it to a prop shop.
-Second question would be: is it a trim tab issue? My trim tab (Sacrificial Node) has been slowly devoured by corrosion and its pointed straight down. I've been doing some reading and aside from replacing it, I was thinking on rotating a few clicks to the left and observe the change. Could this adjustment fix my issue?

I have attached some pics of my current trim tab condition.

The trim tab is not set properly. Take along with you the tools to adjust it, and try different settings until you are happy. I suggest going huge on the setting at first, to see which way it should go.

Jeff

PS: There's a rule on which way to turn the tab, but I can't remember it. Anyone out there know it?

that tab needs replacing...if the boat pulls to starboard move the trailing edge to starboard and vice versa...but there is more to it than that....the position of the motor has a lot to do with it..do you have power trim? 920-929-5040 is the number for mercury assistance...i would call them on the prop question...if nothing else find out what prop they shipped as standard on that engine...if they dont ship with props then talk to your local dealer as they normally rig out with a prop depending on the boat...you got to have the correct prop or close to it to even get started..
on the tilt to the left..the motor must be mounted correctly to start with...square with the transom...the boat bottom should have no hook etc...
the boat i am running now had a tilt to the left the faster i went...it was a new boat in 1994 with a 90 evinrude with power trim...by the time i realized i had a problem the dealer was out of business...i added trim tabs and overcame the problem...ran the boat til 2010 with no problem except the tabs cost me about 4 mph...then i replaced the motor with a efi 4 cycle 60 merc..same weight as the 90 but the boat sets about an inch higher at the transom with the 60.....needless to say i know the boat well..it runs different..i dont think i would have need the tabs to start with if i had started with a 60...the only thing i can figure was the torque was higher on the 90 and possibly a defect in the bottom of the boat...the boat is rated for 100 hp...both engines top out at the rated rpms...

Thanks, will try adjusting a new tab today and see how it goes. It does have a power tilt/trim but it didn't matter much for the setting, I tried different positions and still angled out to the left. Once I adjust the trim I will update. Hopefully I don't need trim tabs its not a really big boat -16ft

I tried a new tab today, I realized that it pulls to starboard instead of port so I moved the tab all the way to the right. It helped a bit, now it got up to 24knt without me struggling too much, however it still does it if you let go of the wheel, always have to be leaning the wheel to the left.
Do you think I might need some trim tabs?

lets go back and discuss just how to adjust that tab...first of all..if you have to go all the way to the right then something is wrong...
do you get the boat up on a plane?where is the motor trimmed to with the power trim...if you get the boat up on a plane can you use power trim to lessen or get rid of the pull to the right..
lets start with a boat setting dead in the water...you are going to give it some gas and bring it out of the hole...you have guessed at your power trim setting as you have no gauge....you apply power...the boat come up on a plane and pulls to the right..at that point you should be able to use your power trim and get rid of the pull..you should be able to loosen your grip on the wheel and the boat should run straight...now you increase rpms til the boat is at your cruising speed...that could be 4000 or 4500 or 5000 rpm or wot..i dont care which...at that point adjust your power trim til the boat just starts to porpoise..back off slightly til the boat does not porpoise...the boat should continue to run true with no pull...it should run like that all day..on most boats you can stop and fish and when you move there is no reason to touch the power trim..the boat should come out of the hole reasonably well and run true...if it still pulls then you want to adjust the little tab...the starting point for that little tab is about what is pictured in your picture..the rear of the tab about 20-30 degrees to the right..
you should not have to adjust that tab all the way to the right...on a boat with the motor mounted correctly and nothing drastically wrong with the hull and somewhere near the proper prop the above procedure should work...
please attach a picture of the boat....i am having trouble finding one on the web....

Don't usually do this but you might??? Benefit from the Whale Tale or Dolpin Tale they install on some outboards.
Is the motor set up right on your boat?
The cavitation plate even or real close to the bottom of the boat.
It should be even with the bottom.
Is it absolutely straight up and down?

@Papyson: Before I adjusted the tab I took it out and around 12 knots it pulled to the right and actually lifts up the starboard side almost completely out of the water. I did as fastjeff suggested before, seeing as adjusting it all the way to the right and then try the settings in-between till i get the correct setting, however once I did all the way to the right the boat actually planes faster, when I'm accelerating it pulls slightly to starboard and once it planes it becomes a little easier but it still feels like if I let go it would go to the right. I adjusted the trim down till I felt comfortable with it, if I put it too down the boat noses up and takes longer to plane so my guess is somewhere halfway, I do not have any working gauges but the gas gauge, I cant see the RPMS, it just marks 2000 once I accelerate, it doesn't fluctuate if i go faster or slower so I just "feel" the engine. I have a SE sport 300 hydrofoil, this helps out with the planing but has not in any way affected the steering issue, the issue was there before the hydrofoil.
Here's a picture of the boat:


I took a video of the issue, it was too big so I tried to compress it to the gif below, you can see how it starts steering to the right and the boat itself looks like its tilting from the right. This is accelerating from about 6knts to 15knts and then it remains tilted like that until plane. (this was shot with the trim tab all the way to the right, the issue was way worse before) You can see how it goes straight but tilted, the tilting is what pulls on the steering. Once it planes it becomes easier and as you said I adjusted the motor trim and the steering got nice and easy then as i revved it up more it started tilting a little bit.
via Imgflip GIF Maker

@jerry: I will check for the position of the cavitation plate with the bottom of the boat.

I bought the boat with the motor installed, I don't know how to check if it is properly mounted. I guess checking the cavitation/hull alignment should tell me.

what is the diameter of the prop?are there any numbers stamped into it....

have you called mercury and talked to them about the proper prob for the rig?

Sorry didn't notice the whale tale in the pics.

A trim tab adjustment only works for a narrow range of speed. Set it up right for WOT and it will pull like crazy at cruising speed (and visa versa), Most people set 'em up fore cruising speeds and live with the WOT torque reaction.

Jeff

that has not been my experience but it may depend on the boat....all my boats have been either flat or a 5 degree V......run straight at 4k and WOT...

You are lucky! (Just kidding.) My old 28 foot Bayliner would pull to one side like crazy at full throttle, but you could take your hand off the wheel at cruising speed.

Jeff

Ok, called Mercury, engine didn't ship with a standard prop as another manufacturer installs the "bolts?" I will try to find out the diameter and pitch today looking for a stamp. I was also wondering how to fix the RPM gauge, could someone point towards which part of the engine would that be connected to? I'd like to make it work in order to find out WOT.
Here are the pics of the engine:
pic 1
pic 2

This is the propeller I currently have, I looked up some youtube videos on identifying the prop but I don't know if I have it right, the diameter is 13 and the pitch is 15? If so is this too big for this boat/engine combo?

Much depends on the boat. You need to get the tach fixed to see what kind of RPMs you get a WOT. The prop should allow it to get to the max RPM for the motor at WOT. Anything too far over or under means you have the wrong prop.