Trim problem 20HP Mariner

J

jayson27

Cadet
Joined
Aug 16, 2004
Messages
15
I have a 20HP Mariner when the throttle is opened the engine swings hard left. The trim tab is adjusted all the way in the correct position but has little effect. The motor is installed on the boat as per the Mercury owners manual. I have tried shimming it in all directions but still acts the same. Very hard to keep in a straight line at full throttle.<br /><br />Any suggestions would be appreciated.<br /><br />Thanks.
 
sangerwaker

sangerwaker

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Jul 29, 2004
Messages
2,059
Re: Trim problem 20HP Mariner

Is the motor mounted in the center of the transom? What type of boat is it on? If it is an aluminum, you may have some dents that are causing your steering problems. I have seen some aluminum hulls that have a twist in them that cause stuff like this too.<br /><br />Good luck!
 
J

jayson27

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Joined
Aug 16, 2004
Messages
15
Re: Trim problem 20HP Mariner

It's a 16' fiberglass. The motor is mounted dead center but I've shifted it both ways to see if it helps......it doesn't. even at low speeds the motor wants to turn the boat to the right.
 
sangerwaker

sangerwaker

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Jul 29, 2004
Messages
2,059
Re: Trim problem 20HP Mariner

Man, that does sound weird to me, bailer. Is the skeg straight? Is the skeg broken off? No holes in the hull are there? I am stumped (easily done). I would keep reposting here as that will keep your topic near the top of the list. Maybe someone with more expertise will answer you. Just a simple ^ or something. A lot of people just type "bump". Sorry I can't be of more help! Best of luck!
 
K

KCLOST

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Joined
Jun 22, 2002
Messages
2,095
Re: Trim problem 20HP Mariner

First you say it goes to the left, then you say it goes to the right....<br />Which way is it...<br /><br />And in regards to the trim tab, you need to turn the trailing edge in the direction of the turn (when looking down on it from above) to counteract steering torque.
 
J

jayson27

Cadet
Joined
Aug 16, 2004
Messages
15
Re: Trim problem 20HP Mariner

The tiller moves to the left. The boat turns to the right. The tab is positioned all the way to the right with some effect but not enough. Someone mention the tilt adjustment??? I'll try anything at this point.....
 
M

makoman515

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Joined
Sep 8, 2004
Messages
8
Re: Trim problem 20HP Mariner

i could suggest trying a different prop. since prop walk in inherantly to the left. im no expert but it seems worht a shot
 
Chinewalker

Chinewalker

Fleet Admiral
Joined
Aug 19, 2001
Messages
8,902
Re: Trim problem 20HP Mariner

Turn the trim the the OTHER direction. It's counter-intuitive...<br />- Scott
 
R

randallwquirk

Cadet
Joined
Jun 27, 2004
Messages
11
Re: Trim problem 20HP Mariner

Trim will definitly make a difference. On a 20 HP tiller, you should have the motor trimed out to about the 3rd hole, if it's not out that far, try it. If you are trimmed all the way down, that's your problem.
 
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