Rudder Offset ~3 degrees

[svonadym]

Hi everybody! I've come to find that the rudder on my 1983 Cape Dory 25D is offset to port about 3 degrees from that of the tiller. I was hoping that it was the tiller that was offset from the shaft, but the key is sound and the alignment with the shaft is correct. So now I'm thinking the fins radiating from the shaft into the body of the rudder are bent. I have no idea how this might have happened; it was before my ownership (honest) and at this point it doesn't really matter. The steering overall remains solid as far as I can tell, but I don't want to take any chances.

My question is: Do any of you have suggestions for actions that might help me understand the trouble more before tearing apart the rudder? I have not yet discussed with a surveyor, but expect to do so with my next haul out.

Thanks in advance for your thoughts on the matter.
- O

[tkeithlu]

You've got a really well protected rudder, so unless the boat slipped off the trailer backwards, I'm not immediately thinking impact damage.

Important question: Is there any play in the system? If you lock the rudder, can you move the tiller even a little bit? If you can, then proceed to find the source. Is the tiller tightly mounted, or has it worn? Are the gudgeons and pintles worn? Can you move the rudder when the shaft is locked?

Second area of interest: Is there any evidence of an impact? Bruise on the bottom of the rudder? Cracks in the geloat around the shaft log? Cracks whre the rudder attaches to the shaft?

Third area of interest: Is anything else out of line? Is the keel straight? Is the rudder straight on the keel?

Three degrees is a lot for a manufacturing error, but it does happen. It is possible that the rudder itself was not correctly aligned with the shaft.

That's all the ideas I have today. Time for a cold beer and a chat with my wife. Good l;uck with it.

[svonadym]

Thank you for your quick input. The only reason I noticed it at all is I had to push the tiller from centerline to port a small bit to keep the boat tracking straight. I don't have any answers to offer yet other than that an underwater visual and scrubbing of the hull and rudder didn't reveal any obvious trouble, nor did I detect lateral movement of the rudder - but harder to tell in the water. I'll look at all of the things you mention once the boat's hauled.

[Manateeman]

The green frog is spot on as always. Our guess...something loose inside the rudder. Just a guess. Follow what the frog said to check..his pad may have low freeboard but he’s a happy frog cause he’s not dinner in Louisiana tonight.
The manatee crew ...too big for a one pot meal.

[GordMay]

Could it just be normal lee/weather helm?

Weather helm is when you have to pull the tiller to weather (toward the wind), in order to keep the boat going in a straight line.
Lee helm is when you push the tiller to lee (downwind) in order to keep the boat going in a straight line.

[HeywoodJ]

Adding to Gord's post/question, when you noticed this what it under sail or under power? Under power, always having to put the helm one direction (at least a small amount) is entirely to be expected. The rotation of the prop, particularly in an aperture installation between keel and rudder exerts some uneven forces on the rudder and the underbody. For reference, our own boat requires 2-3 degrees of port rudder when motoring. Under sail it requires from zero to 5 degrees in either direction depending on how we have the sails balanced.

[tkeithlu]

QUOTE: "The only reason I noticed it at all is I had to push the tiller from centerline to port a small bit to keep the boat tracking straight."

That changes the entire question. If the "problem" appears when sailing but not under power, Gord has got it. When you have the boat out of the water, set the rudder straight and look at the tiller.

A weather helm just means that you do not have the trimming of the sails and balance of the rig quite right, and 3 degrees may be the best you can hope for.

A small helm could also be present under power. You have just one prop, and it is trying to flip the boat opposite of its turning.

[GordMay]

Originally Posted by tkeithlu

... A small helm could also be present under power. You have just one prop, and it is trying to flip the boat opposite of its turning.

Propeller walk [aka: asymmetric thrust] is the term for a propeller's tendency to rotate about a vertical axis [aka: yaw motion]. The rotation is in addition to the forward or backward acceleration.

Knowing of and understanding propeller walk is important, when maneuvering in tight spaces. It can be used to one's advantage, or it can complicate a maneuver, if the effect works against the helmsman.
A right-handed propeller, in forward gear, will tend to push the stern of the boat to starboard [thereby pushing the bow to port] and turning the boat counter-clockwise, unless the rotation is corrected for.

“How To Use Prop Walk for Single-Screw Boat Handling” ~ by Tor Pinney
➥ https://www.passagemaker.com/technic...-use-prop-walk

[svonadym]

Thanks to all for your comments. To clarify: I *first* noticed it when underway. After investigating further, I found the offset. I did this by securing the tiller to center and then jumping in the water to check the position of the rudder. Finding the rudder offset to port, I removed the tiller hoping it was cockeyed on the post, but no such luck.


My concern is that, while the tiller/rudder currently feels solid, there is internal damage that will reveal itself when least convenient. I'll use tkeithlu's suggestions, hoping they reveal clues to help me determine next steps. Thanks again

[tkeithlu]

I suspect that you have done what you can in the water. The concern that you've got is right on the point. If it's just an assembly misalignment, you can live with it. But if the rudder is internally hemorrhaging, you need to know that, because having the rudder break loose as you come about or the bilge suddenly fill with water could spoil your whole day.

[TrentePieds]

svonadym said: " I *first* noticed it when underway."

"Underway" just means not at anchor and not moored. We need to know if you were underway under engine power alone, under sail power alone or if you were "motor sailing"

Your first test should be under sail alone, first on one tack and then on the other. If you sail trim is correct, you should have about a 3º offset of the tiller to the weather side of the boat. The offset should be about the same on each tack. This is what is called "weather helm" and is to be regarded as a safety measure.

If when under sail alone you tiller is "offset" to the leeward side of the boat you have what is called "lee helm" and that indicates that your sail trim is NOT correct. By altering the trim so it IS correct, the boat show "weather helm". Normally lee helm is to be taken as an indication that your sail trim is grossly outta whack :-)!

When proceeding under power alone, provided your boat has an inboard engine, which I don't think was the CD25's native configuration) with a propeller in an aperture just forward of the rudder, the "prop water", because it forms a spinning vortex will tend to deflect the rudder on one side. The boat will then tend to turn ever so slightly to the side to which the rudder is deflected, and yu will have to apply "opposite" helm to keep a straight course.

A deflection of the tiller of 3º would be perfectly normal in this circumstance, and it will, obviously always be a deflection to the same side.

If you are "motor sailing" the latter condition obtains but will be interfered with by the effects of carrying sail.

If your power is an "egg beater" on the transom, there is no way of knowing what is going on.

The way your rudder is constructed, the rudder stock, to which the tiller is attached, goes all the ways down through the rudder and terminates in a "gudgeon", a female part of the hinge, which is part of the keel. Impact damage is very unlikely, and that the tangs within the blade where they are welded to the stock should be broken as a result of corrosion is also unlikely, though not impossible.

All the best,

TrentePieds

[Searles]

You may have a slightly twisted rudder stock, not unknown,especially if everything feels tight .⛵️⚓️

[davegrillo]

Hi. I have the same. Had you solved the problem if it was a peoblem at all?
Thanks