Would you trust a rudder stock weld?

[NateHanson]

I've heard a couple disparate opinions on repairing a bent rudder stock, and I'd like to see what the fine folks here think. The scenario is a spade rudder with a 1 1/4" stainless pipe rudder stock (1.65" o.d.), bent about 10 degree right where the stock enters the blade. I've heard from someone who fixed this problem by cutting away the top 6" or so of the blade, cutting off the stock below the bend, machining a piece of stainless rod to fit inside the stock, and fitting another piece of pipe over the other end of that. Welding it all with 316 wire, and polishing it up good.

A fellow who makes rudders, however, has expressed the opinion that without a whole lot of fancy passivating, and metalurgical mumbo jumbo, no stainless weld below the waterline (especially in a low-oxygen environment like the inside of a rudder) can be trusted for more than a few years.

For me the question is academic, because I have worked at splitting my rudder blade in half, to remove it from the stock and web, and that painful process (yes, the foam is totally dry and holding like crazy glue stuck to duck tape ) has me solidly committed to a rebuild-the-rudder course of action. Or find a replacement.

Anyways, the subject has gotten me wondering, and when I wonder about stuff like this, I like to hear what you folks think about it.

Thanks, Nate

 

[rwthomas1]

Well, why not just straighten the tube? The reason I say this is I used to ride motorcycles. Riding motorcycles means I have crashed them, more than once. It is, or was, quite common to straighten bent fork tubes if there was no kink in them, as in, the bend was smooth. I had this done many times. I would look into simply straightening the rudder stock. Its even easier since you are stripping off the rudder blade. Any shop with a heavy press that has a clue how to use a dial indicator will be able to do this. Would I trust it? Absolutely. IMHO, rudder stocks are extremely overbuilt for obvious reasons, ie. litigation. Bending a stainless tube smoothly 10* and then straightening it will not reduce its strength in any way that you could measure or notice. I would do this and trust it without hesitation. RT

 

[NateHanson]

Interesting Rob. I had figured that the tube would be weakened by bending it twice. And basically it already proved weak, as it bent originally at that point without any impact. The tiller broke during a blow, allowing the rudder to turn atwartships, and presumably the boat riding at the mooring during a stormy week gradually bent the rudder.

But I guess even a new rudder stock isn't going to be any stronger than this one was.

Anyways, reusing the stock/web would save considerable expense. I don't mind too much rebuilding the blade, but looks like it would cost a good $500 or so to have a new stock and web fabricated.

Anyone else want to weigh in on the strength of a bent/straightened stock?

 

[Guy Stevens]

Stainless Steel VS regular steel Rudders VS motocycles

One of the key differences here is that the rudder is Stainless Steel which work hardens significantly faster than regular steel. Two flexes of the tube one to bend it and the other to bend it back is two too many.

Your insurance company if you have one would not likely cover the loss of the boat due to loss of steering if you loose the steering after "Fixing, the problem by straightening it."

Guy

 

[treilley]

Isn't the stock already welded at the blade? My understanding of rudders is that there is a stainless stock and then there is a piece of stainless sheet that is welded to the stock that the foam and fiberglass is then built around. Is this not oxygen starved?

 

[NateHanson]

Isn't the stock already welded at the blade? My understanding of rudders is that there is a stainless stock and then there is a piece of stainless sheet that is welded to the stock that the foam and fiberglass is then built around. Is this not oxygen starved?

My understanding is that the stock extends about 3/4 of the way to the bottom of the blade, and some horizontal flat-stock is welded to the stock at a few points to support the blade.

Those welds can be passivated and electro polished when it's initially manufactured, and I don't think you can do that when the stock has a rudder blade on it.

 

[Cory B]

Not that I know what I'm talking about, but my "gut" tells me not to trust a shaft which has been bent twice not to bend again.

If I were to try to fix a shaft on the cheap, I might be tempted to straighten it (no cuts or welds), and assuming it was hollow like most Ericson shafts, sleave it internally to regain any lost strength.

 

[Loren Beach]

Somewhat Agree with the straighten-it idea, depending on degrees of bend, but in this game the insurers hold all the aces.

It seems Doubtful that the shop that straightens that shaft and sleeves it is going to put their name on a written certification atesting to the strength.

Speaking of a bent rudder shaft, I know of a sailor that got his rudder/shaft assembly replaced by his insurance company after it was bent by a submerged log. As I recall, he added in some his own money to upgrade to a "Booth design rudder" for his Catalina 27, and gained some boat speed.

Sidebar: about 5 years ago I accidently hit a small deadhead at six knots, and it was driven down and resurfaced again... behind the transom...
If it had been slightly more bouyant it likely would have nailed the propulsion gear or rudder... and I would been calling my ins. co. first thing...

Loren

 

[NateHanson]

How do you sleave it 20" down from the top? Is the narrower pipe inserted from the top, and only secured at the top with a weld? Or drilled and pinned at a couple places?

I like that idea because I frankly don't think this design has enough strength for my liking. I'm just not sure of the techniques for this kind of thing, as a woodworker myself.

 

[Gary Schroeder]

a chain's weakest link is where?

Nate,
Looking down the road for unintended consequences, if you upgrade the rudder post, will a different component "give" the next time the boat experiences the event that bent the rudder post? And would it be something you can live with?

 

[rwthomas1]

It would probably be best to speak to an engineer or metallurgist if you are considering straightening it. I respect others opinions however the very slight angle, 10* as you stated, and if it is a smooth bend would have me straightening that sucker out.

The rudder stock is pretty small, IMHO, but I am used to the 3 1/2" pipe on my E38. Upgrading the rudder stock to a stronger material is your only option without major surgery. Again, maybe its time to speak with an engineer about a different grade of marine stainless that is stronger in the same OD. That or have a custom carbon tube fabbed up.....

If you did straighten it then an internal sleeve would likely be a very good idea. The correct OD of the smaller tube may or may not be available to fit snuggly into the rudder stock. The material could be turned on a lathe and hand fit, trial and error method. The other option would be to epoxy the sleeve in place. A simple crossbolt, maybe the existing quadrant bolt or a weld at the top would hold the sleeve.

This all depends on what your boat is worth, how much time and money you have and if you are willing to roll the dice. A new rudder, complete is also just a phone call away at Foss Foam.

RT

 

[NateHanson]

Yeah, I've got my call in to foss for an estimate, so I know what my bottom line is.

If rebuilding this stuff will cost $400 and 2 days of my time, I'd probably jump at an $800 job from Foss. I have no idea what their price will be though. Hope to hear back soon.

 

[NateHanson]

$900 from Foss Foam, (and $100 or so to ship it), so call it an even grand.

I'll have to take it to a stainless shop around here to get an opinion on straightening and sleeving. And figure out what it would cost to do that, and what it would cost to just have them fab a new stock.