rudder alignment

[the kuz]

Don's thread on prop offset got me thinking about running gear. If I remember right, the rudders on my 36C are towed in about 5 -10 degrees (will measure next time she is out). How much tow in should be there? Boat turns well in both directions. Thanks, Bob K

[SKYCHENEY]

Don's thread on prop offset got me thinking about running gear. If I remember right, the rudders on my 36C are towed in about 5 -10 degrees (will measure next time she is out). How much tow in should be there? Boat turns well in both directions. Thanks, Bob K

Call Hatteras and they can give you the specs for tow-in on your particular boat.

[Avenger]

For my 36C Steve at Sam's had me contact a former Hatteras employee about that. He told me 1/4 to 1/2 inch of toe-in (stand in your boat facing the bow, look down at your feet, it means exactly what you think it does). He was very specific about the toe being in instead of out, said the boat would track better and not overwork the helmsman or autopilot. Hope this helps.

[the kuz]

Thanks, I guess I have some work to do next time she is out. If I'm following you right, when I stand behind the stern and face the bow my rudders are towed OUT about an inch ( stern end of rudders closer together than at the posts). I have been blaming that old Wood Freeman for the little bit of slow weave I get on auto pilot, although she tracks fine from the helm. Thanks again, Bob K

[TedZ]

Toe in is to prevent vortex oscillations...the antenna in the wind, the marker in the current, the double triangles on the phone lines etc. etc.

Any tiny bit that prevents them from shaking (oscillating) is plenty. More and you scrub speed.

Ted

As a sort of off topic PS the formulae the engineers were using up until the late 80's to calculate frequency and amplitude of the oscillations was wrong. Corrected by a Cambodian Princeton engineer who got fired for releasing a white paper on the topic without going through "channels!" Of course, he was right! When they tried to hire him back, guess what he said!!

[Avenger]

Bob,

You're welcome, and correct re: toe-in/out. I'm battling similar issues with mine. As received mine currently has almost five inches of toe-in. Looks like the speed-brake on the Space Shuttle when you stand behind it. Be aware that the rudder arms have a seven degree offset on the keyways, so if you flip them over you get quite a change. If I flip mine over I end up with about an eighth of an inch of toe-out. The big problem is that Hatteras used tapered pipe thread on the tie-rod so it's not adjustable. No offense to any plumbers out there (in fact I give them a lot of credit for working with this stuff) but pipe is just crude, crude, crude. I'm working on setting it up with some kind of straight thread and locknuts so I can fine tune it. As Ted pointed out straighter is better, so I'm aiming for that 1/4 inch. Good luck with your project.

[yachtsmanbill]

See if you can retrofit an automotive toe adjusting sleeve--like a turnbuckle--L&RH threads. You will still need to make an initial adjust on the drive vs. the drag link.

[MikeP]

It may be interesting to note that I asked that specific question of Hatteras re our 53. This was their e-mail back to me:

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

I found it interesting that whether it was toed in or out was not an issue. I checked it and found that it was 1" with the trailing edge of the rudders an inch further apart that the leading edges. I think I'd call that toe-in but some say that's toe OUT and the opposite would be toe in. Oh well, per Hatt, it doesn't matter which way it is on a 53.

[Boss Lady]

Since we are not talking about adjusting the steering of ferrari, I plan to start my rudder alignment exactly straight, and then add little bits of toe-in until there is no oscillation. My rudders came setup like a speed brake too.

[luckydave215]

Think about rudder induced drag for a moment.
What direction is the apparent water flow as it leaves the transom of your individual boat? Is the flow still diverging, (like it is at the bow) or is it converging toward the centerline?
If the flow is diverging, it makes sense that there would be less rudder induced drag if there was toe in (point your toes at each other, pidgen toe style) and less drag with toe out of the flow is converging.
The rudders shouldn't be aligned straight because you want some constant steering linkage load to prevent slack in the gear, and the rattling and wear that would result.
It also makes sense that , just like vehicles, you want some toe in in the rear steering gear (rear suspension on a independent rear suspension car) to make the vehicle (in this case boat) wander less.
Anyway, regardless of boat speed, less drag is better.