MacGregorSailors.com

Ross

And whoever else may be interested

RUDDER BRACKET BUSHING for the 26M
13 photos

http://s1224.photobucket.com/albums/ee3 ... 20bushing/

Happy Power Sailing

Octaman

Now that's what I'm talking about! Thanks Okky (that's Australian for octopus)

Did you make the custom rudder post arm or did that type come with your model?

Let's post and discuss design mods for our dodgers before winter is out.

Regards ..... Ross

<<Did you make the custom rudder post arm or did that type come with your model?>>
No, that was standard on my 2004 model.

<<Let's post and discuss design mods for our dodgers before winter is out.>>
Sure thing.

Best wishes,

Octaman

Very well done, Octaman! I like it.

I did nothing to address the bushing at the lower pivot point on mine. (Err...yet).

The upper bushing itself looks similar to what I did, (actually, the dimensions look identical) except I placed a second “seal” (interference fit) made of 1/8” thick urethane on top of that bushing (where you have masking tape), which seals both water out and resin from seeping in between the shaft and bushing. I also grooved the bushing (vertically, with a grinder) so as to "captivate" it from turning within the resin matrix, which was probably not necessary.

I then cut the bottom out of a yogurt-type container (only transparent, so I could see the level as I filled it), inverted and taped that over the whole affair, and poured polyester resin into it. After it hardened, I removed the "forms", which left a shiny tapered post to support the bushing and seal. I will probably put some fibreglass matting over the outside of that this spring, to make its attachment to the boat more robust.

Then I will asses my lower pivot points, now that you’ve got me thinking about it!

- Brian.

Guy's, what method did you use to open up the top area for the bushings? Hole saw? How much?

Ross

I didn’t open up the top existing hole. I just fibre glassed the bushing onto it.

Ditto. The top hole just becomes "clearance" for the shaft. It's one reason I did this immediately before my boat hit the water and the hole got worn enough that the original position was more difficult to determine. But I'm sure that wear would take years to become significant, even on Lake Erie.


There is only so much space above the shaft where the bushing can fit, without interfering with the steering arms, and that's what dictated the maximum dimensions of the addition.

Adding the bushings to the lower stainless steel brackets is on my to do list. In my boat the factory fiberglass torque tube towers in the hull of the boat had become pretty worn and as a result noisy when floating in the water with the rudders down. (click clack all day long).

It was very easy to fabricate a friction fit delrin bushings to the tower tops, I posted this modification in the mod section this past summer:

http://www.macgregorsailors.com/modt/in ... ?view=1508

I cut the bushings square, out 3/4 inch material. There in no way that it could ever rotate. I used a hole saw to drill them undersized and then a set of precision reamers and a little sanding to get a friction fit. You can see the installation process in the link.

Chris.

Chris,
Very nice.
The only drawback I see in your technique is that when the delrin bushings become worn and need to be replaced you need to dig them out of the fiberglass encapsulation.
The reason why I used an SS ring and then put the tough plastic bushing into that was so that the bushing can be easily replaced when it gets worn.
Just a thought.
Happy power sailing,
Octaman

Either way, have you noticed any significant change in looseness, or tightness when the temperature varies from hot to cold? I've looked at stainless steel thrust bearings for the top position but inserting and properly positioning seems too much of a hassle now that the rudders have been dropped two inches, and most of the free space used up.
How good do you think Delrin is over time? When I did my rudder mod(s) I noticed - but didn't record - that the tubes were very slightly out of round. Not a large amount when I used my micrometer but perhaps of some effect if I try to bore a Delrin bushing to fit.
I suppose, by comparison, anything in opposition to the silly fiberglass holes will be far superior!

Ross

Greetings!

Delrin (I have first-hand experience with its use in various industrial applications) is an excellent choice of material for the bushing. Given the 3/4" thickness (=large bearing surface area), the relatively clean environment, and the low forces involved, I would expect to see decades of use with minimal wear from it, with no lubrication. So easy replacement is not a high priority in its design.

I used UHMW. While good, but not as ideal as delrin, it was available (I had a piece sitting around, free), and I don't expect that wear in it will be a concern in my lifetime.

IIRC, the tube on my boat was within .002" of round at the bearing location, and a little more than that closer to the top, and turned freely without any friction when complete. This somewhat surprised me because I filled my fruit cup "moulds" a little more than I planned, which surrounded the tube itself in polyester resin for about 1/8"+ at the top. Since the resin shrinks when it cures, I expected some tightening and gripping of the shaft when I first turned it, but it was zero.

Made me think that a "quick and dirty" fix might possibly be to not make and embed any bushing at all, and just make the whole thing out of resin, and maybe a light coating of oil as a release agent on the shaft. (No XD-100 jokes here, pulease!) Might even try wrapping the tubes in a bit of Teflon tape to give some clearance(?) Use what's easily available to you, is my personal rule. Even if they were a little snug initially, they would soon loosen up in use. This would be easy to confirm by testing it on a piece of pipe, to see how "grippy" it becomes when it sets, if you were so inclined to try this method.

- Brian.

Thanks Brian, good points!