CD33 - where/how is the rudder load carried?

[davidmcq137]

Hi All,

We are nearing completion of a major refit of a 1981 CD33. The driving change was to remove the original MD-11C diesel and go with electric propulsion (Bellmarine 15W), backed by a 6kW WP generator.

As part of the steering system rebuild, we were wondering how the vertical load (the weight of the rudder) is intended to be carried. We are guessing the pintle/shoe at the bottom aft end of the keel .. but there is also a rather beefy collar that is held to the rudder stock with a grub screw ... it sits on top of the pillow block near the top of the rudder stock.

That collar and the pillow block don't look to be designed to carry any vertical load .. but I am curious if anyone here has more insight on this question. It would be possible to slightly raise the rudder from the pintle and have the collar and pillow block carry some load .. but that does not seem right to us...

Any insights would be appreciated. Happy to post more on the refit if there is interest.

thanks
Dave McQueeney
Owls Head, ME

[Paul D.]

I've no experience removing my rudder but I know the shoe at the bottom of the keel is a pretty stout bronze fitting. I have worked extensively around the rudder shaft/quadrant area replacing steering components and reglassing the below decks autopilot mount behind the quadrant but I've not removed the rudder stuffing box fittings. I don't think there is any sort of collar holding weight in that section. Here is what my original 1982 CD 33 manual says about its construction.

"The rudder assembly consists of two pre-molded fiberglass half shells completely fi l l e d with a reinforced polyester compound. This compound surrounds the pre-formed rudder shaft creating a solid rudder of exceptional strength. The blade is further reinforced with two layers of glass tape applied to the shell joints.

The rudder shaft is a solid bar of type 304 stainless steel, 1-1/2" in diameter bent to fit inside the rudder shell. A bronze gudgeon casting is imbedded in the bottom of the rudder to accept the bronze pintle casting which is attached to the keel. The pintle is set in polysulfide bedding compound and fastened onto the hull with bronze rods passing through the solid heel portion of the keel. The entire casting is then faired with polyester putty and glassed into the keel. This eliminates the electrolysis problem commonly found when stainless steel weldments are used in seawater."

[davidmcq137]

thanks Paul, appreciate your own experience and the quote from the manual.