Rudder Rebuild Advice Needed

[Jumping Flea]

Hi Guys,

My rudder of my CD30 was badly split, so I removed it, split it open, and chiseled out the filler.

[img]http://www.capedoryaja.com/swrudder1.jpg[/img]

[img]http://www.capedoryaja.com/swrudder2.jpg[/img]

Lots of fun.

[img]http://www.capedoryaja.com/swrudder3.jpg[/img]

I was surprised to see the rudder post was only a "J" shaped rod.

[img]http://www.capedoryaja.com/swrudder.jpg[/img]


I looked through the online manuals for later versions and anything that was pictured was of the same design.
Really late models didn't show the rudder post.

I know it has lasted 30 years, and, with only a little surface rust which can be brushed off, it is still solid.
The rudder shell is in good shape as well.
I thought about just filling it back in and sealing it up but since I have come this far, should I "beef it up"?

If so, what are your recommendations?

Thanks for your input,
jf

[SPIBob]

Judging from the drawings in the various CD owner's manuals that are viewable on this site, only the CD's w/o propeller apertures have straight rudder shafts that require beefing up by welding flat stock to the shaft that extend back into the plane of the rudder blade to increase torque resistance.

With the CD 25D and on up, this torque resistance extension back into the plane of the rudder blade is accomplished, not by welding on additional structures, but by bending the shaft itself, first running aft and down into the plane of the rudder (the bend beginning at the very top of the rudder) and then back again toward the front edge of the rudder (the arc at the very end of the shaft), again in the plane of the rudder.

It seems that this bending of the shaft within the plane of the rudder blade is actually an improvement over the welded-on extensions in terms of providing beefed up torque resistance. With the welded-on extensions method, the weldments themselves can become a problem in terms of cracking, corrosion, poor quality welding, etc. With the bending method, this is not an issue.

If one agrees with this analysis, I think the answer to your beefing up question is "No, it's not necessary. Just clean up, refill, and reseal the two rudder blade halves." IMHO

Good luck, Bob

[Matt Cawthorne]

If your aperture is anything like the CD-36 I would do a nicer job of fairing the leading edge of the rudder in the aperture when you rebuild. The front of the 36 rudder is very blunt. It just has to be a drag and rudder effectiveness issue.

Keep a serious eye out for pits in the metal, particularly in the region where it would be close to the edge of the glass. Such pits would be due to crevice corrosion and, if large enough could contribute to an early fatigue failure some day.

The J shaped tube generates a prying action between the two halves of the rudder. You mentioned that the rudder was split. Was it the two sides separated from one another? Was there a failure of the glass that joined the two halves? Was there any glass joining the two halves? I would certainly beef up whatever split!

[tartansailor]

Previous posts referring to clean up and put back together, also bending to a "J" seem to me to be all quite workable.

Here is what happened to me: the yard ape hoisted my CD-25 with a strap under the rudder, twisting it, and the shaft.

A skilled artisan welded a 3/16" plate the exact profile of the rudder to the straightened shaft. He then filled and faired with epoxy & glass.

Yes there is more weight, but the weldment runs the full length of the blade, so the concern of dropping the rudder during a cruise is a thing of the past.

I believe, but not positive, that I posted pics about a year ago.

Dick

[johnny of STORK]

Lots of fun, indeed! I did exactly this same job last year on STORK, although the internal cracking wasn't quite as bad. I went ahead and had a couple of heavy straps welded on, one across the "j" and back toward the rear edge, and another across *that*, the "j", and out into the lower corner. Don't know if this will help in the long run, and if I had known what I know now, I probably wouldn't have opened it up in the first place. I sure feel better in heavy night crossings, when visions (and noises) of stuff falling apart are the worst.

Johnny

[Jumping Flea]

In response your questions & comments-

It seems that there was no tape across the top edge of the rudder - this is where it split - about an inch deep. I knew water had gotten in there and that is bad so we cut the rudder open with a sawzall and pried it apart.

Haven't inspected the metal too carefully yet, but I will. I am still considering welding something on to it - but will probably reassemble as is if the rod looks good.

I will take your advice about fairing the forward edge of the rudder for better perfromance.

Thanks!