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Old 19-03-2014, 07:25   #1
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Make a new rudder

Our boat's rudder stock is bent, the leading edge of the rudder is cracked. There are no signs of water coming out of the rudder. The boat's on the hard- a Catalina 30

So, I'd like to make a new rudder.

Can you recommend a source for rudder stock tubing?

Which Stainless Steel would you recommend- 316 or 316L (other?)

Any other suggestions?
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Old 19-03-2014, 08:08   #2
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Re: Make a new rudder

Do a google search for Online Metals and others, they should have schedule 80 pipe in 316L, you want 316L because you will be welding the inner framework to the rudder stock.

I went through the same thing about 10 years ago for a Hunter 37 and decided to buy a new rudder from Foss Foam in FL. Unless you have the ability to weld SS and make a mold it will be more cost effective to buy a new rudder.
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Old 19-03-2014, 08:16   #3
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Re: Make a new rudder

Ok. Thanks for the reference to OnlineMetals.com

They look like a good supplier.
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Old 19-03-2014, 11:05   #4
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Re: repair a bent rudder

Along the same lines, my "new" boat has a bent SB rudder shaft when picked up by misplaced sling during Sandy. Looks bent backward about 10-15 degrees. PO just removed a little at the top of the rudder where it was hitting the hull. I would have to dig a 30" deep hole to drop the rudder. Not sure what the shaft is yet, assume SS but if so, can it be straightened? Is 10-15 degrees worth worrying about? (you can see the difference between the boot stripe and the bottom of the rudder)
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Old 19-03-2014, 11:42   #5
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Re: Make a new rudder

Dunno about cost, but catalina direct will sell you a new one complete.

Catalina Direct: Rudder C-30 HDPE Type "A" or "B"
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Old 19-03-2014, 14:59   #6
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Re: repair a bent rudder

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Originally Posted by Sailorman Ed View Post
Along the same lines, my "new" boat has a bent SB rudder shaft when picked up by misplaced sling during Sandy. Looks bent backward about 10-15 degrees. PO just removed a little at the top of the rudder where it was hitting the hull. I would have to dig a 30" deep hole to drop the rudder. Not sure what the shaft is yet, assume SS but if so, can it be straightened? Is 10-15 degrees worth worrying about? (you can see the difference between the boot stripe and the bottom of the rudder)
Ed
I would think anything past maybe 5 deg would start to affect the weight of the helm adversely.
Unless it was previously OVERbalanced, I would be looking to fix it, if it were mine.
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Old 19-03-2014, 15:18   #7
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Re: Make a new rudder

I wouldn't try straightening the rudder while it's on the boat, the force required might break something else. A 15deg bend is quite a bit. Did you check the rudder bearings and support for damage when the rudder bent the first time?
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Old 19-03-2014, 15:50   #8
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Re: Make a new rudder

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Did you check the rudder bearings and support for damage when the rudder bent the first time?
No, I purchased it on the hard and have no intention of trying to straighten on the boat, hence my comment about digging a 30" deep hole to get the shaft out. Boat is 5 hours away and will start making 3 day work weekends in April. Just trying to get preparations in order ahead of time. This is my first unsupported rudder. Trying not to have an "Alpha42 rudder".
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Old 19-03-2014, 15:51   #9
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Re: Make a new rudder

pda-
Have you considered using a composite rudder stock instead of stainless? Eliminates many issues down the line, including the need for metal welding.
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Old 19-03-2014, 15:54   #10
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Re: Make a new rudder

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Originally Posted by jeepbluetj View Post
Dunno about cost, but catalina direct will sell you a new one complete.

Catalina Direct: Rudder C-30 HDPE Type "A" or "B"
Catalina Direct is one of those places that doesn't know much but will try and sell you anything.

As to straightening- good idea but the straightening process will reduce the rudder stock strength to 40% of the original value.

Another idea- If you want- trim the rudder as someone just mentioned. Then, clean it up and re-glass effected areas. Then place a smaller diameter stainless tube down the existing rudder stock. Pour in the super high density foam around the old and new tube (maybe down the middle of the new tube also?).

'Worth a try. And alot cheaper than making a new one.
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Old 19-03-2014, 15:58   #11
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Re: Make a new rudder

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pda-
Have you considered using a composite rudder stock instead of stainless? Eliminates many issues down the line, including the need for metal welding.
Yes, I have. The problem is that when carbon fiber fails...it flails. Stainless will just bend and it's not likely to snap off.

If I'm wrong about this let me know. Yes, I do understand it's a matter of sizing.

Welding is no problem.
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Old 19-03-2014, 16:11   #12
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Re: Make a new rudder

Stainless will just bend, "but"...

The problem is that a stainless rudder post will always be subject to crevice corrosion since there is anoxic (still) water inside the rudder itself. Doesn't matter how you seal the post where it enters the rudder, water will get past that seal.

Once this has happened, the crevice corrosion can lead to a sudden and complete rudder post failure, just as sudden as any composite failure. And the beauty of this failure mode is that it is guaranteed to happen. The only question is, five years? Or forty? At some point, it is going to happen and the only question is when.

So if you plan to get rid of the boat in five years, no worry, use stainless. If you plan to keep it for 20 years, pay very good attention to the seal on the rudder post and inspect your rudder to see if it has gotten waterlogged. All in all...I can't help but think that an excessively strong composite shaft will "never" break in normal use. As opposed to stainless, which is laying in wait, conspiring at the molecular level, just sulking down there and waiting for the Least Convenient Moment.

I have no idea what, say, a two inch thick graphite and kevlar composite rod (not tube) stock might cost. But hey, that's accounting not engineering. There's always a 7-11 you can rob, right?
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Old 19-03-2014, 16:50   #13
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Re: Make a new rudder

Ours is 1984. The post is solid 4" diameter SS with 3 ribs welded on. The overall length is about 10 feet. We dug the hole in the ground to remove and to put it back. The hole is easy. (use a mattock) No bends but total delamination. We rebuilt on the same SS using US Composites 635 Thin resin. Fiberglass , Epoxy , Composites, Carbon Fiber - U.S. Composites, Inc. For filler, I compounded the 635 resin with microballoons. 10 gallons of balloons with 3 gallons of epoxy yields about 13 to 14 gallons of syntactic foam. It is 3000 psi compressive strength and totally waterproof for ever. I skinned the rudder with vacuum bagged carbon fiber.

My various rebuild photos are at Member Galleries - Cruisers & Sailing Photo Gallery on this site.

There is a deck port for an emergency tiller so I could install a lift eye on the top of the post in a conveneint tapped hole. In our case, the mizzen boom provided a belay point for an 8-part block for lifting the rudder into the hull. Top post mounting is a large plastic bearing. The rudder post is tapered and ends in a 2 inch stub in the skeg mounted bottom bearing. I replaced the bearing using IGLUS. igus® - iglide® Plastic Plain Bearing Product Selector These were way inexpensive. the bottom bearing was 7.50 !!!!

Are you sure the rudder post is hollow? I have worked on one other rudder (Heritage One Ton) and its post was also solid 5" diameter. I have looked at a few others in the boat shed and they also appear to be solid.

If the post is solid, I would seriously consider straightening. Find a body & frame shop with hydraulic rams and frames. If the post is hollow, the risk is that the section might flatten. Stuffing anything inside, especially if it is glued in will be worse than useless. 90 % of a hollow shaft strength is in the outer 20% or so. This means that almost no additional strength is realized by making the shaft solid after a certain wall thickness. The only benefit is that the solid is more resistant than hollow to buckling from bending. Bending stress is greatest where the post exits the hull at the bottom of the bearing on a cantilevered design.

I agree with several of the other posts - unless you are good and confident, buying a new rudder from the maker or a good after market fin shop is the best. We commissioned a new center board from:

Competition Composites Inc. | Canada's Premium Composites Fabricator

Philip Locker
Competition Composites Inc.
613 599 6951

listing of their boat fins. Seversl Catalinas here.
http://www.fastcomposites.ca/site/marine/foils-a-z/
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Old 19-03-2014, 17:23   #14
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Re: Make a new rudder

I would very much recommend to read the information from a specialist on rudders, rudderstocks and materials first.
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Old 19-03-2014, 17:46   #15
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Re: Make a new rudder

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Originally Posted by Nicholson58 View Post
Are you sure the rudder post is hollow? I have worked on one other rudder (Heritage One Ton) and its post was also solid 5" diameter. I have looked at a few others in the boat shed and they also appear to be solid.



I agree with several of the other posts - unless you are good and confident, buying a new rudder from the maker or a good after market fin shop is the best.
I looked at your rudder making pictures a few days ago and I'm glad you replied as I couldn't find them again. Thanks for the references.

Yes, I'm certain the rudder stock is hollow. If I would (not could) afford the solid stainless rudder stock that would be great. But I won't.

'Not too concerned about the skill level of making a rudder. I just need to understand what are my best options for longevity and strength. I'm tending toward 316L because my boat is a Chesapeake bay cruiser taking short trips in never-too-heavy weather. And, as I said earlier, I just want to make one.

Any other ideas or suggestions are much appreciated.
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