Rudder Alignment

[chris piazza]

I noticed yesterday while walking around the boat that the rudders appear to be out of alignment. While standing in-line with shafts for reference I noticed that the port rudder was straight in line with the shaft, however the starboard rudder was turned out maybe 1-2". I had noted before I put the boat away it was handling a little different, sort of sliding to the side during slow speed docking, I wasn't sure but it just did'nt feel right. I did'nt hit anything or ground it so how would this get out of alignment? I'm sure there is an adjustment on the steering to correct it but I would like to know how it happened. Does anybody know the correct measurement for center to center on the rudders?

Chris
Superior Nights 53C

 

[bostonhatteras]

different hulls and different speeds dictate the settings, however what do your rudders measure out to if you center both of them? could it be that they both have a certain amount of toe, but becouse one is inline with the shaft the other looks way out? what happens when you line up the rudders according to the autopilot centering info? the rudders usually are not aligned with zero toe for vibration purposes i believe and 10 degrees toe in is probably a decent estimation for your boat. the rudders are aligned via the transmission rod that is between the tiller arms that are keyed to the rudder posts. the transmission rod has a treaded section with lock/jam nut and this is where any adjustment is made.
dont forget to center the hydraulic steering before you make any adjustments and also the auto pilot feedback needs to be realigned after this work.

 

[rwetherington]

Chris,

your rudders should both look alike. align you rudder straight, then measure the front of your rudders from one rudder to the other, then measure your rudder in the back from one to the other. Now you will need to move both rudder in at the front 3/8 of an inch so that when you measure the back of the rudders and the front of rudder again you have a 3/4 toe in on your rudders. just look at your feet and put them straight and then move your toes in to get the picture of what i mean by toe in.

 

[chris piazza]

Okay so what your saying is both rudders should have a 3/4" toe in? Or is it 3/4" total. I thought I had read somewhere that they indeed had to have a toe in to stop "rudder flutter" (kinda sounds like a medical condition). If that is true the way mine currently are, toe out, would cause a big handling issue. I have only briefly looked at the steering system in boat. Is it just a matter of adjusting one of the steering shafts out to get the proper toe in?

Chris
Superior Nights 53C

Boston hatt I just re-read you post and that answer my question thanks

 

[MikeP]

Ask Hatteras; they will tell you the specs for your specific boat.

I asked them 3 years ago and posted this message in this forum. the following is the message I posted including their response:

"I just received the toe-in info I requested yesterday eve for the 53MY from Hatt. Here is their email response:

You need to have 3/4" to 1 1/2" of difference between the leading edge
and the trailing edge either in or out.

Best Regards,

Hatteras Yachts Customer Service Department

It's interesting that their post clearly indicates that it doesn't matter whether the rudders toe in (wider at back) or out (wider at front)."

The thread is here: http://www.samsmarine.com/forums/showthread.php?t=3798&highlight=rudder&page=2

 

[chris piazza]

Mike,
If I understand what your saying than nothing is wrong with mine the way it currently is? If i center the steering than I would have about 1/2"-3/4" toe out on each side. Per Hatteras toe out is just the same as toe in as far as performance, plus if I leave it toe out I will get more stern lift per Karl. So I guess it fixed it self, I like it when that happens.

Chris
Superior Nights 53C

 

[rwetherington]

Chris,

Hatteras does toe in Viking does toe out. You should have a 3/4 total toe in. Only the Hatteras's that go over 30 kts have more toe in. Worked there 37 years last 10 in service and that is all I ever told anyone. Never have done one any other way.

 

[MikeP]

Interesting. Did Hatt change the recommendations since you worked for them? Or was there different "opinions" within the service dept?

 

[Jackman]

Wondering how it would differ for a 32' FB? I have to check mine. Since my repower I significantly increased my speed and wonder if I have to change the toe in ect for the rudders?

 

[rwetherington]

on the answer form Hatteras did you tell them what model you had? Again the newer boats do have as much as 2 1/2 inch toe in, but the older models only used 1/2 to 3/4. So I check with one of may older friends in the service dept. and he agreed with me 3/4.

On the 32 if you picked up speed and the boat is a little squirrely then you may want to increase the toe in.

 

[REBrueckner]

I believe my 1972 YF rudders are slightly off center relative to the shafts...to permit the shafts to be extracted without removing the rudder. I don't remember if the rudders were inboard or outboard relative to the prop shafts, I think slightly outboard....I would think that position would dictate whether toe in or toe out....anybody know???

 

[Trojan]

The leading edge should be pointing out. It will work ether way. But with the leading edge pointing in on some boats, will cause the boat to over steer or wander. One inch of toe is more than enough in most cases.

BILL

 

[Sonny]

I believe my 1972 YF rudders are slightly off center relative to the shafts...to permit the shafts to be extracted without removing the rudder. I don't remember if the rudders were inboard or outboard relative to the prop shafts, I think slightly outboard....I would think that position would dictate whether toe in or toe out....anybody know???

The rudders are off centre of the prop shafts to permit shaft removal without having to remove the rudder. On slower single screw boats the rudder actually has a hole in it to accomodate this. If the rudders have "toe in" this means the leading edge of the rudders will be closer to each other than the trailing edges. If the rudders are parallel to each other, they have no toe in or out. From my understanding of the toe in/out of rudders, the benefit is in smoothness. Imagine a flag on a flagpole in a stiff breeze. It whips side to side. Imagine that in your steering gear, all the minute tolerances working themselves back and forth until they become wide gaps. Now imagine you grabbed the flapping end of that flag and moved it off centre then the flag would be more like a sail on a properly trimmed sailboat - smooth and no flapping. If you move the rudder off parallel from the keel you effectively "fill the sail with air", but the opposite rudder must have an equal and opposite setting to maintain neutral handling.

I in no way condone sailing despite the sailing analogies

 

[Genesis]

The idea is to maintain some preload on the steering system no matter the rudder position. As noted the rudders are offset from the centerline of the wheels so the shafts can be removed without having to drop the rudder involved.

If you have absolutely straight rudders you can get a "fluttering" condition when the rudders are dead straight. This both creates vibration and is hard on the equipment.

If there is a small amount of toe in or out then there is always some load on the system from water movement in a consistent direction irrespective of where the rudders are set, avoiding this problem.

If the rudders are set to toe out slightly there will be a small additional amount of stern lift applied, as the rudders will act when straight ahead to "funnel" the water coming off the wheels towards the centerline of the vessel between the two rudder blades. Whether this is desireable or not depends on the boat. Some hull designs run a bit better with toe in, some with toe out.

 

[chris piazza]

Karl, my boat is a 53C, so what your saying is if I want a little stern lift I need to toe out? And the toe out would be on the trailing edge (rear) of the rudder?

Chris

 

[Genesis]

If you want a bit more stern lift you want the TRAILING edges inward slightly (toe OUT; the "toe" being the forward part of the rudder) Don't go overboard with the adjustment; more is not better as you lose efficiency; what you're doing is choosing which way the (necessary) preload is vectored, not trying to intentionally create lift. In other words you're picking the side effect to a necessary thing.

Think "nozzle"; you are concentrating (slightly) the prop wash together towards the centerline. Its not a big change but you should see a (small) difference in handling on plane. If you pass the same volume of water through a smaller space the velocity increases.

Whether this will be an improvement for your boat depends on how it runs now. There's only one way to know for sure and that's to try it.

 

[stormchaser]

Hummm....53MY could always use a little moer stern lift. I'll have to check it this spring. If it's trailing edge out, I think I'll switch to trailing edge in. What effect does this have on low speed maneuvering?

 

[SKYCHENEY]

Before we all go changing to toe-out, let's find some others who have done it. Anyone?

It would be nice to know if they see any advantage to changing before you go to the work of trying it and perhaps then changing it back.

 

[stormchaser]

Agreed...but if nobody has been the guiney pig, I will volunteer. I get 3 free short-hauls a year at my marina...so it's a no cost thing, even if I have to haul a second time to undo it. The only problem would be that I have limited experince with my baoat, so i don't know that's I'd see/feel the difference.

I do know that to get Saraswati to plane off, I need full throttle and full bow down on the tabs and it still takes a while to get that nice flat wake and 17+ knot top speed...once she's on plane, I can back down and she stays "up." With a little more stern lift, I would HOPE to be able to stay up at a slightly lower RPM or get a little more speed at the same RPM?

 

[Sonny]

Storm you don't have to haul the boat as all adjusting is done inside the boat, unless the water is too cold do do a dive to get the initial measurement. Once toe in/out has been determined all you have to do is measure the length of the tie bar, which is what you would adjust to alter the toe.