Building a New Rudder ... v 2.00

[Ben Diss]

Since I messed up my first attempt, I thought it best to document the second try in a new thread.

For reference, here's a link to the old thread:

http://www.ec12.com/discussion/topic.asp?TOPIC_ID=239

[Ben Diss]

Before I begin, I'd like to get some opinions on the material for the rudder shaft. I used brass in the first one, but I'm not entirely sold on it because it is heavy. What about a stainless tube or hard aluminum?

Please speak up and let me know your thoughts on this. I'd appreciate hearing everyone's opinion.

-Ben

[Ben Diss]

What about a carbon rod? How about a brass tube with a carbon rod inside?

[Larry Ludwig]

Carbon is wonderful, expensive, light-weight.. and brittle.

She don't bend... now.. I don't recommend bending your rudder shaft... but snapping one off is even worse. Aluminum works, is lighter than brass and you can gently bend if back if you step on it and bend it (NOT that I have ever done that of course) and have a chance to keep racing until you get back to the shop and replace it.

Brass is a little heavier, and a little stronger and a little more pliable... because you can break the aluminum rod if you step on the rudder AGAIN and bend it worse (NOT that I have ever done that) and break the #$%$#^#* thing off... because you forgot to put a new one on when you got back to the shop (NOT that I would do that)

[Ben Diss]

How does one go about bending the rudder shaft? Better yet, how might one step on it? Wouldn't that do a bit of damage to the boat too?

Second question: Is 5/32" rod a common size for the rudder shaft?

-Ben

[yachtie]

Ben - is it not quicker/easier to "trim" rear edge of the rudder till it measures???


Stainless is weapon of choice down under for rudder shaft.

Chris
NZL1 Longtack
&
NZL110 Swept Away

[kahle67]

Yes, have done the carbon rod iside the brass tube before. Works great. Make sure to coat the rod well with epoxy so there are no voids.

RK

[kahle67]

Oh yeah! And sorry to have brought up the oversize thought on the other thread. Why not cut it down and reshape it?

Reichard

[Ben Diss]

I could trim it down and reshape it, I suppose. I'd have to sand all the glass off ...again... then trim, reshape, reglass, fill, prime. I figure I might as well try again and see if I can improve it.

Anyone ever try stainless tube (not rod)? I am leaning towards brass tube with carbon inside only because I have it on-hand.

-Ben

[Pink66]

Ben, I have been making my fiberglass rudders for several years now with 5/32" stainless shafts and they work great. If you are concerned about the shaft weight, think about this. My rudders are hollow and float so they actually increase buoyancy in the back of the boat. Your balsa core rudder will do the same. Don't use a pure carbon shaft. The carbon is great for bending strength, but the torsional load you will be putting on it will tear it apart.

Good Luck

Mark

[Ben Diss]

Mark-

Thats an interesting thought. Since the rudder is below the waterline wouldn't we want them to NOT be buoyant? Has there ever been any discussion about adding some ballast to the lower part of the rudder?

Also, do you use a solid rod not a tube?

-Ben

[Pink66]

Ben, I don't think you want the rudder to not float. If something happens to your servo linkage, the rudder would be laying on the bottom of the pond. That's not fast!! Also, I want to keep my ballast low and centered in the boat not on an appendage sticking out off the back of the keel.

Yes, my shaft is solid 5/32" stainless rod. A fully finished rudder ends up weighing about 2 1/2 ounces. Hope that helps.

Mark

[Ben Diss]

I've decided to make the rudder as light as I can. Since I have 5/32 brass tube and 1/8 carbon rod on hand I'm going to use that. I'm also going to use balsa instead of a hardwood dowel.

I'm starting with one piece of 3/4" square and another one 3/4" x 3". Here are the pieces as I get started. In this pic I've already bent the brass tube.

[Ben Diss]

Next comes the slot for the shaft. I marked the center and used the mini-mill with a rounded nose bit to make the slot.

[Ben Diss]

I cleaned the slot out with a 5/32 rod to ensure a good fit. Then I cut a small piece of balsa to fill the slot. I marked and drilled the hole for the bent part of the shaft. Here are the parts ready to be glued.