Hard to steer to starboard

[7228sedan]

I have a 28 foot Luhrs with a single engine inboard. As the speed increases the boat becomes harder to turn to starboard. Is this due to the thrust of the prop? She turns to port with next to no effort, however starboard is a different story. RH rotation on the prop & no power assist. This is my first inboard boat, I'm not too sure what to expect.

[gonzo]

It may be a misaligned shaft. Do you have any history on the boat?

[7228sedan]

This is the boat that I had to replace the transmission in & I replaced the motor mount bed with; If you recall. Your assistance has been a tremendous contribution to why it is in the water & running right now (thank you). So I know there was 1) rotted mounting timber. 2) burned up V-drive. Gould my aligning of the transmission cause that? I assume you're referring to the alignment of the strut to the hull? If the strut was too far to port; I see how that would cause this.

Yes, it is due to the thrust of the prop. It is a right-hand prop, no?

[7228sedan]

Originally Posted by mark775

Yes, it is due to the thrust of the prop. It is a right-hand prop, no?

Yes it is a right hand prop.

right hand props push the stern to stbd. (in forward), thereby making it harder to push it (the stern) to port with the rudder. The more thrust (the faster you go), the more effect this has.

[7228sedan]

That's what I thought & hoped it was, as Gonzo referrenced earlier in the thread; I was concerned with a missaligned shaft. I assume the only way to correct this is a power assist system?

[gonzo]

You can install a trim tab on the rudder to compensate.

[7228sedan]

Originally Posted by gonzo

You can install a trim tab on the rudder to compensate.

I'm assuming it would be a horizontal tab? Where on the rudder would it be located?

[Bglad]

It would be a vertical tab and does not have to be very large. Attach it to the side of the rudder along its trailing edge then bend it to counteract the force from the prop. It does not have to be very large in fact on ski boats they grind the trailing edge to decrease pressure on one side or the other. Advantage of a tab is you can jump over with a crescent wrench, pliers or a hammer and tinker until you get it how you like it. I think a tab that was 2 to 3 inches tall hanging an inch aft of the rudder blade would be plenty to trim the rudder. If the trailing edge is thin enough to work with a hammer you might be able to roll it and accomplish the same thing without a tab. If you want the rudder to go right roll the trailing edge to the left and vice versus.

On a rudder with a flat edge on its aft end I once installed a trim tab by drilling and tapping the trailing edge and installing a slotted plate that projecte out from the trailing edge of the rudder. It only had to project about 3/16 to 1/4 inch to have the desired effect.

[7228sedan]

Originally Posted by Bglad

It would be a vertical tab and does not have to be very large. Attach it to the side of the rudder along its trailing edge then bend it to counteract the force from the prop. It does not have to be very large in fact on ski boats they grind the trailing edge to decrease pressure on one side or the other. Advantage of a tab is you can jump over with a crescent wrench, pliers or a hammer and tinker until you get it how you like it. I think a tab that was 2 to 3 inches tall hanging an inch aft of the rudder blade would be plenty to trim the rudder. If the trailing edge is thin enough to work with a hammer you might be able to roll it and accomplish the same thing without a tab. If you want the rudder to go right roll the trailing edge to the left and vice versus.

On a rudder with a flat edge on its aft end I once installed a trim tab by drilling and tapping the trailing edge and installing a slotted plate that projecte out from the trailing edge of the rudder. It only had to project about 3/16 to 1/4 inch to have the desired effect.

So in my particular situation, as she is hard to turn to starboard; I'd need to attach the trim tab on the trailing edge of the rudder & bend it toward the starboard side slightly? Would it matter what side of the rudder it was attached to? I assume the starboard side would be preferred. I'm picturing more or less an adjustable wedge on the side of the rudder that extends slightly beyond the trailing edge.

[Bglad]

Right on your wedge thought but reversed on the bend in the tab. Use the tab to steer the rudder the direction you want it to go. Bending the tab to the left will push the back end of the rudder to the right aiding your right turn.

[tunnels]

Is the rudder directly inline with the prop shaft ? also what is the shape of the rudder ? any pictures of whats there .

[7228sedan]

Yes the rudder is directly behind the prop. Sorry I don't have any photos of my actual rudder; however I was able to locate a picture of a sister ship with the same rudder. This boat in the photo is a twin engine, while mine is a single. The rudder is however a perfect match. Following is the link to the page; if you coppy & paste this address, it'll take you right to the photo.

http://www.yachtworld.com/core/listi...FUnited-States