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Old 23-10-2023, 18:18   #1
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Aluminum vs composite rudders

2014 leapard 44 with rudders failing - I have asked exactly why. Anyway the yard is suggesting new rudders. Aluminum was factory spec, yard is suggesting composite rudders may last longer. Thoughts?
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Old 23-10-2023, 18:42   #2
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Re: Aluminum vs composite rudders

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Originally Posted by Mahana Kai View Post
2014 leapard 44 with rudders failing - I have asked exactly why. Anyway the yard is suggesting new rudders. Aluminum was factory spec, yard is suggesting composite rudders may last longer. Thoughts?
Aluminum is very susceptible to galvanic corrosion and can disappear within a few days with stray current corrosion. I'd go with composite.
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Old 23-10-2023, 18:44   #3
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Re: Aluminum vs composite rudders

Exactly as boatpoker said. You should never need new rudders. Go composite
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Old 23-10-2023, 18:49   #4
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Re: Aluminum vs composite rudders

Personally I've never seen an aluminum rudder. Only bronze, stainless, and composite. Aluminum doesn't strike me as a great rudder material.
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Old 23-10-2023, 20:15   #5
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Re: Aluminum vs composite rudders

Do you mean aluminum rudder posts?

Our first cat had solid aluminum rudder posts. Can't imagine aluminum rudders on a production boat.
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Old 23-10-2023, 21:13   #6
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Re: Aluminum vs composite rudders

I'm with GGray - surely just rudder posts. And how are the rudders failing?

Stainless shafts and web with epoxy laminated foam or cedar is a great way to build a rudder. Sure you can go composite too, but why would the yard not want to use the most common form of rudder construction - stainless shafts and composite infill? Sounds odd.
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Old 24-10-2023, 10:01   #7
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Re: Aluminum vs composite rudders

I am sorry i am not in the yard and able to get photos. I am asking for some. They say the failure is in the bearing assemblies. It’s possible that what they are calling “composite” is what is being referred to here as stainless with composite “build ups”.
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Old 24-10-2023, 12:49   #8
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Re: Aluminum vs composite rudders

My rudder is fiber glass. I there a big problem with fiber glass constructed rudders?
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Old 24-10-2023, 13:58   #9
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Re: Aluminum vs composite rudders

If you ever consider sailing to the Mediterranean, stainless rudders might be a good choice.
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Old 24-10-2023, 16:11   #10
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Re: Aluminum vs composite rudders

Mahana,

It sounds as if you are being asked to make a decision with no real idea of the problem. If you are not there at the boat, understanding exactly what the problem is, I reckon the yard may be trying to fleece you.

Most rudders are stainless steel shafts with fibreglass (composite) of some sort making up the foil shape. The bearings act on the stainless shaft. Maybe your shafts are aluminium but this is much rarer. You really need to know exactly what the problems are with your rudders before you can make an informed decision as to how to proceed.

You could be up for over $10 000 to produce two new rudders for a large cat. So I would be very cautious about proceeding without understanding what has happened. Bearings are a different issue. They are not part of the rudder but part of the boat (in the rudder tube). Bearings can be cheapish (machined delrin or acetal) or more expensive (self aligning roller bearings).
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Old 24-10-2023, 16:23   #11
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Re: Aluminum vs composite rudders

Mahana Kai, I have seen composite rudders with aluminium shafts that severely corroded. The owner had no idea he had aluminium shafts, so he liberally applied antifoul over the rudder/shaft area and sure enough a few years later a small portion of the exposed rudder shaft was badly pitted. That is a rare occurrence and 99% of the production sailboats I survey have a stainless-steel shaft with fiberglass blade.
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Old 25-10-2023, 02:57   #12
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Re: Aluminum vs composite rudders

Evidently, the Leopard rudder shafts [& bearings?] may have been Aluminum Tubes
https://www.international-boat-spare...107-leopard-46

https://groups.io/g/Leopardcatamaran...ts/82482984?p=
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Old 26-10-2023, 18:38   #13
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Re: Aluminum vs composite rudders

oK - it is not the rudders it is the shafts and bearing assemblies. I also wonder about previous work.
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Old 26-10-2023, 23:09   #14
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Re: Aluminum vs composite rudders

Ahh, that makes more sense. If I was you I would install composite tubes like I have had for 23 years no problem. You can get them in different radii and thicknesses. I would also look at glassing the top of the tube to the boat. It looks like these ones are floating. I guess that is okay, I don't know Leopards, but I hope the rudders are on a skeg, or I can't understand how the rudder works. Where is the top bearing pushing onto the hull?

Composite rudder tubes can be epoxy glued and then glassed into the hull so that you don't need that 5200 or whatever at the bottom. The sealant on the bottom of the tubes looks very dodgy to me.
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Old 03-11-2023, 09:44   #15
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Re: Aluminum vs composite rudders

Sailboat steering systems will not be reliable if there is no guide bearing located above the quadrant.



The photo doesn't establish whether there is an upper guide bearing supporting the rudder shaft located above the quadrant. Suggest that you verify this point.



Since you report this to be a repeating failure, I recommend that you engage a naval architect to survey this yacht's steering system and prepare repair or modification specifications. The problem is likely to repeat or move to the next steering "weak-point" if you omit this critically important step.
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