New Boat owner 1975 merc 165 straight 6 steering problems

I have never owned a boat before and I just bought a 1975 merc 165 with a straight 6 and I am having some steering problems at low speeds it seems like the boat doesnt want to turn all the way or keep straight when I give it some gas the steering tightens up and I can turn better but it still wont drive straight I looked at the cable and everything looks fine I can turn the wheel and see everything work any ideas would help like i said i have never owned a boat before and dont know anything. if you need more info please ask

Re: New Boat owner 1975 merc 165 straight 6 steering problems

All single engine i/o's do that wander.

Solutions:
1. Learn to live with it.
2. Buy a boat with twin engines.


If you had trim tabs you can drop them all the way and it somewhat helps.
Doubt you do.

Re: New Boat owner 1975 merc 165 straight 6 steering problems

First off, using puctuation in your posts makes it a lot easier to decipher what you are describing.
If I got it right, you are saying that your boat wont keep a stright line when going slow. At idle speeds and flat wake zones, correct?
Welcome to boating.
The slower you go, the less pressure (friction/drag) there is against the straight lines of your hull. (keel, and chines) less pressure equals more drift or "yaw".
Plus there is a certian ammount of play in every steering system. In boats this is especially true. As a boat gets older, the amount of play gets worse.
The drive unit is your rudder, going slow also lessens the amount of pressure against the sides of it, allowing the torque of the spinning prop to "wag" your drive like a tail.
And the shorter a boat is, the more pronounced the effect becomes.
By adding a little more throttle, the thrust of the prop increases the pressure against these straight lines, and that effectively overpowers the props torque effect.

This concludes todays lesson on the physics of hydro-dynamics

Re: New Boat owner 1975 merc 165 straight 6 steering problems

Thanks for your replies. After looking at it more I noticed that the steering wheel insn't straight when the prop is. So I think that was most my problem.

Can I take off the steering wheel and then put it back on straight or do i have to do anything else?

When I was loading the boat back up it made it really hard to keep it straight going on the trailer any advise would help.

Thanks for anyones help

Re: New Boat owner 1975 merc 165 straight 6 steering problems

Ayuh,... Wrap a piece of tape to the Top if you can't Remember...
Fixin' it Ain't worth the effort involved....

Re: New Boat owner 1975 merc 165 straight 6 steering problems

Really cause it looks really easy cant i pull the nut off the steering wheel then repostion the wheel so its straight and then let her fly or is there something im not seeing.

And if anyone can help me I have 2 internal gas tanks
the guy I bought this boat from said i needed to fulsh the tanks

i took off the gas line and poured gas into the tank but nothing came out i then blew air into the lines and didnt hear anything

any advise

Re: New Boat owner 1975 merc 165 straight 6 steering problems

Really cause it looks really easy cant i pull the nut off the steering wheel then repostion the wheel so its straight and then let her fly or is there something im not seeing.

Click to expand...

Ayuh,... It's a Keyed tapered shaft,.. Not splined....

As for the fuel tanks,... Ya just gotta LOOK.... All hulls are so different...
Follow the hoses... removing the tanks might be possible, or Not...
Ya Gotta LOOK..

Re: New Boat owner 1975 merc 165 straight 6 steering problems

for the steering. agreed with above posters. at slow speed, a vhull wanders. very minor steering input is required if ya wanna go straight and ya gotta plan ahead of the yaw to counter act it or you'll weave even worse. in time, you'll get used to it and be able to keep a straight line. when at speed, you should have a trim tab on the drive too. this can be adj. to make the steering feel evenly tight when turning port or starboard. but the tab is adj. for whatever your favorit speed and load and trim is. anything other than that, the steering will likely pull one way or the other.

as for the steering wheel not being straight. you'll get used to that too. mine ain't straight either i don't think. in time, you'll get used to it and it won't matter the steering wheels position. if it bothers you, put it on straight.

as for the fuel tanks. the reason ya take them out is to clean or replace them. usually rust is the enemy that your fighting. it'll plug up your fuel system. if the rust is bad, you'll have no choice but to remove and clean them. if it's minor. ya may get away with R&Ring fuel filters repetitively. my boat had the rustys in the fuel tank when i got it. it's taken about 3 years of many tanks of fuel. but i'm now down to 1 fuel filter a year. compared to 3 or 4 the year i got it. i took my chance on flushing out the rustys that way, but it appears to have worked since i'm down to 1 filter a year.