djohns19 And Trim-Tabs

[Hooty]

I don't understand your reasoning moving the trailing edge of the trim-tab in the direction the boat pulls to. Seems like it should be the other way.<br />?<br /><br />c/6<br /><br />Hooty

 

[DJ]

Re: djohns19 And Trim-Tabs

Hooty,<br /><br />Considering the engine is on the rear of the boat: And you are steering it, you actually are moving the front of the engine (tiller arm or steering arm) in the opposite direction of the direction you want to turn the boat. Push the tiller arm to the left-boat goes right, and visa versa.<br /><br />The steering trim tab is acting like an extension of the boat seering wheel.<br /><br />Let's say that the boat wants to go right (starboard) all the time. The front of the engine is wanting to go left. If you move the trim tab (trailing edge) to the right, then the front of the engine will want to go to the right.<br />If you turn the trialing edge of the tab in the direction of the pull-it will make the engine want to go the other way.<br /><br />Think of the bolt that holds the trim tab to the cavitation plate as a pivot point. The front of the engine will want to go the opposite way of of the trailing edge of the trimtab. The reverse would be true if the tab were on the leading edge in front of the engines steering pivot point.<br /><br />Did I completely confuse you?

 

[suzukidave]

Re: djohns19 And Trim-Tabs

Djohns, I'm with Hooty on this one which means I'm confused but not saying you are wrong. <br /><br />Let's start with a rudder on a small sailboat. If the trailing edge of a rudder is pointing to starboard, the boat will steer to starboard. Same thing with an outboard: if the back of the leg and prop is pointing to starboard the boat will steer to starboard.<br /><br />Now if the trim tab trailing edge on the outboard is pointing to the starboard, isn't it just like a little rudder attached to a big rudder and won't it do the same thing as the big rudder and thus exaggerate the effect of a turn of the big rudder (engine) to starboard and diminish a turn to port?<br /><br />Therefore, don't you want to point the trailing edge of a steering tab in the opposite direction to the way the boat is pulling? <br /><br />I'm interested to understand this. It may redeem me for my grade 11 physics grade. <br /><br />By the way Hooty, what does the "C/6" at the end of your posts mean?

 

[Down South]

Re: djohns19 And Trim-Tabs

Djohns is right. The trim tab is easy to get confused on which direction it should be positioned. I've had to sit down at the back of the motor and think about it more than once before I got it right. Anyway it's not the boat you are trying to turn, It's the motor- Motor turns one way and boat turns the other way.

 

[blifsey]

Re: djohns19 And Trim-Tabs

I've been reading these threads and not wanting to admit I was also confused Down South, your last comment that the trim tab should control the motor, not the boat not makes it all clear. Now, if I can only remember that when I have need to adjust the thing!<br /><br />BL...

 

[DJ]

Re: djohns19 And Trim-Tabs

Hola, Hooty, Suzuki Dave.,<br /><br />Down South is right. It confused the bejeebers outta me to the first time I fooled with one.<br /><br />In your sailboat example. If you push the tiller left-the boat goes right. True, the trialing edge of the rudder is pointing right, but the tiller handle is pointing left. Same as an outboard or I/O prop.<br /><br />The trim tab throws another pivot point into the mess.<br /><br />Thanks, DS!

 

[Hooty]

Re: djohns19 And Trim-Tabs

Hooty concurs with djohns19. Trim-tab changes attitude of engine which changes attitude of the boat. Gotcha.<br />Thx.djohns19<br /><br />c/6<br /><br />Hooty

 

[DJ]

Re: djohns19 And Trim-Tabs

Hey there Hooty,<br /><br />Still didn'nt tell us what c/6 means??

 

[Hooty]

Re: djohns19 And Trim-Tabs

c/6 = check your six

 

[DJ]

Re: djohns19 And Trim-Tabs

Hooty,<br /><br />Got ya, will do!<br /><br />THX.

 

[GarageGuy42]

Re: djohns19 And Trim-Tabs

Gentleman I have a question on this trim tab issue.<br />I have a friend that has a Bravo2 I/O with a dual stainless prop and it doesn't have a trim tab. He has power steering but I wouldn't think that would matter. The prop is another question, HE say's they turn independently of each other. One right and one left on the same shaft. Is that true or is he pulling this info out of his butt.<br />Someone enlighten me please!

 

[DJ]

Re: djohns19 And Trim-Tabs

GarageGuy42,<br /><br />Your buddy is 100% correct. In theory, no need for a trim tab. <br /><br />Power steering is necessary because turning the angle of thrust on high horesepower units can be difficult.<br /><br />Actually that unit is a Bravo 3.<br /><br />The dual props were pioneered for recreational boats by Volvo, they call it DouProp.