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Discussion Starter · #1 · (Edited)
Over the past year or so I've seen many reports of rudder failures and/or loss in cruising boats. Apart from age and "cycles" like we've talked about in the past, I'm wondering what the cause is. And I'd love to get feedback on this from the great designers we have around here - as well as the salts.

I'll lay out my hunch to get things started, based on my own experience...

Last year the boys and I did a 150-mile offshore delivery of a friend's Pearson 365 in some relatively "rough" conditions. The seas were maybe 3-4 meters, and steep (left overs from a big storm in the Gulf) and winds were in the high 20s. We were, unfortunately, sailing with that stuff just forward of our starboard beam. So, though it was a gentle beating for the most part, it was pretty jumpy and rolly. We were steering with AP.

The next morning things were calming down and we suddenly lost steerage. I grabbed the wheel and confirmed we could still steer, while my friend's son reset the AP - thinking it had just been a glitch. It was fine for a minute or so, then we lost steerage again. I asked him to take the wheel and I opened up the lazarette.

The AP, a ram arm model, had ripped off its base, where it had been bolted, and was rolling around. At least we still had the rudder. We obviously shut down the AP and steered the rest of the trip by hand.

I remember thinking about the fact that there had been a lot of force applied there to rip that thing out. Then I started thinking about all the offhsore races I'd done - hand-steering only - and never recalled feeling that kind of force through the wheel - even in rough conditions.

So, my first question...is AP (especially ram arm versions) a liability in big seas? My hunch is that it is and that is one of the primary causes in these rudder losses we're seeing on cruising boats.

AP is almost continually used by sailors (especially short-handed cruisers) these days on long trips. And it especially used (I think) when things get tough because it seems to be safer than standing in the cockpit steering 24/7.

But when you look at the boat motion in these videos - you see that there is a tremendous amount of lateral force being applied to the rudder:



Now, that is an F10/11 in the second video. If I were unfortunate enough to be caught in that I'm pretty sure we'd already be on a drogue...not pushing the boat like that. I'd be way too scared.

But, you'll notice that in both of these cases, the boat is being hand-steered. It seems to me that this provides a great deal of "cushioning" (response time and give) for the rudder over a mechanical ram.

If your stern is swinging through 20-30 degrees at surfing speed on AP...what kind of force are we talking about on the rudder and stock? It seems astronomical.

I this a cause of the failures we're seeing?
 

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I think most rudder failures will be due to undetected fatigue on older boats, and aggressive weight-saving engineering/scantlings on 'new', esp dedicated race boats.

The undetected fatigue fails when suddenly subjected to unusually heavier loads, perhaps not even serious storm conditions, whereas the other is an engineering/design 'fail'.
 

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I've always thought that an undersized, rather than over-sized, autopilot, had a lot going for it, as a self steering set up. Mainly because, if I am going to have a component break from being over stressed, I would rather have it be the AP than the rudder.
 
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"I'm wondering what the cause is."
Falling standards and the rise of the hoi polloi, Smack.
First you let people play tennis in anything other than tennis whites. Then you let them use (horror) colored balls. Then they start checking out the yacht club, and buying those cheap plastic boats to avoid the mundane cost of having a proper crew maintain the brightwork. And sooner or later what happens? That's right, those plastic boats are now mass built "to a price" for those same rabble, who have no idea of what a proper rudder and rudder post should look like, much less what they will cost. And no, heaven forbid they have the yard crew inspect and replace the rudder from time to time, like everything else on a proper yacht.

Now, a proper rudder, a one-piece weldment of monel or marine bronze, carefully built up on a solid rudder post of the same material, or, a substantially similar one-piece composite rudder? Simply can't fail the same way, can it? There's always someone looking for a cheaper answer.

So you see, what you have been noticing is simply the fall of Western Civilization, brought on by a laxity in tennis, spreading to yachting, and wreaking havoc among all the proper folk.
 

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What I've noticed in sailing a lot of miles, often when the winds have been strong (<25 knots) with good sized waves is how much load there is on the steering system. You really notice this with vane steering where you watch the vane steering the wheel. There is just a constant motion in the system. Even if the wheel is not turning the load on the lines from the wind vane is constantly changing from one side to the other. Loads on rudders and autopilots are the same with probably a couple thousand loadings and unloadings happening per hour. I agree that failures are just a result of fatigue. I think there are probably three reasons why most people sailing very long distances in moderate sized boats prefer vanes to electric pilots:
(in increasing importance)
1 Vanes are quieter - you don't get constant motor noises
2 Your electrical demands are much lower with a vane
3 Vanes are more reliable and generally easier to fix, i.e. wear factors are less and less critical. Our Monitor is pretty tired after 30,000 miles but it still works. I have a bag full of parts from Scanmar to replace all sorts of worn bits when we get back to Grenada.
 

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Discussion Starter · #6 ·
"I'm wondering what the cause is."
Falling standards and the rise of the hoi polloi, Smack.
First you let people play tennis in anything other than tennis whites. Then you let them use (horror) colored balls. Then they start checking out the yacht club, and buying those cheap plastic boats to avoid the mundane cost of having a proper crew maintain the brightwork. And sooner or later what happens? That's right, those plastic boats are now mass built "to a price" for those same rabble, who have no idea of what a proper rudder and rudder post should look like, much less what they will cost. And no, heaven forbid they have the yard crew inspect and replace the rudder from time to time, like everything else on a proper yacht.

Now, a proper rudder, a one-piece weldment of monel or marine bronze, carefully built up on a solid rudder post of the same material, or, a substantially similar one-piece composite rudder? Simply can't fail the same way, can it? There's always someone looking for a cheaper answer.

So you see, what you have been noticing is simply the fall of Western Civilization, brought on by a laxity in tennis, spreading to yachting, and wreaking havoc among all the proper folk.
I thought it was just case of green furry balls.
 

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The AP, a ram arm model, had ripped off its base, where it had been bolted, and was rolling around. At least we still had the rudder. We obviously shut down the AP and steered the rest of the trip by hand.

I remember thinking about the fact that there had been a lot of force applied there to rip that thing out. Then I started thinking about all the offhsore races I'd done - hand-steering only - and never recalled feeling that kind of force through the wheel - even in rough conditions.


The bigger the wheel, the less force you feel. How long was arm on the AP? Not the piston mind you, the ARM. The arm on most APs that I've seen is 6" or less, give or take.



If you were to steer with a wheel that has a radius equal to the arm length, THEN you'd feel what the AP feels.

MedSailor
 

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Or try steering just using the spokes 6" out from the hub. We got a chance to go on one of the America's Cup 90 footers in Auckland. Very big wheel and a boat set up well - even for tourists). With such a big wheel even on a huge boat the steering was incredibly precise and easy. Move the wheel an inch and the boat turned.
 

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A bigger quadrant would require a bigger ram and a bigger pump to drive it and pretty soon you've gone beyond your design budget ..Maybe less restrictions on designers Or build it your self and do it right.
 

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What I've noticed in sailing a lot of miles, often when the winds have been strong (<25 knots) with good sized waves is how much load there is on the steering system. You really notice this with vane steering where you watch the vane steering the wheel. There is just a constant motion in the system. Even if the wheel is not turning the load on the lines from the wind vane is constantly changing from one side to the other. Loads on rudders and autopilots are the same with probably a couple thousand loadings and unloadings happening per hour. I agree that failures are just a result of fatigue. I think there are probably three reasons why most people sailing very long distances in moderate sized boats prefer vanes to electric pilots:
(in increasing importance)
1 Vanes are quieter - you don't get constant motor noises
2 Your electrical demands are much lower with a vane
3 Vanes are more reliable and generally easier to fix, i.e. wear factors are less and less critical. Our Monitor is pretty tired after 30,000 miles but it still works. I have a bag full of parts from Scanmar to replace all sorts of worn bits when we get back to Grenada.
The other part of wind vane steering is that it Will Not steer the boat if you have too much sail up. I wonder how many autopilot failures are the result of continued use in sporty conditions without reduction is sail area. The skippers have no idea of the forces being exerted on the rudder, quadrant, cable and wheels because the electric auto pilot is overcoming those forces....until it breaks.

Pretty common to see the broken arms, fittings and attachment devices on the electric, ram driven autopilots. It would be something I'd be taking a look at before every passage, tightening the brackets, looking for fatigue cracks, etc.
 
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Smack I like the Idea - question. Give me a couple of weeks to wrap my mind around the potential difference in material fatigue between the auto pilot and human muscles. human muscles would be more forgiving (a little more give) and a slower reaction time as well as the ability to look ahead at what is going to happen next. Trying to fit that together is hard enough and I am sure there are more differences. Something to look at, mybe a little longer than weeks.
 

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The lateral forces on a rudder are enormous.
A spade designed rudder is going to be a disadvantage.
Personally, I like the long keel with a keel-mounted rudder. It will still have similar lateral loads, but it does not have the same aggressive bending moments that the spade rudder has.
Ease your boat too in the heavy weather stuff.
Don't push her so hard.
Respect her.
She will last longer if you do.

Last summer I fitted a Hydrovane autopilot. It serves as a reserve rudder also. I remember going round Rattray Head (NE Scotland) at night once with a young crew. I asked myself silently what I would do if the ship's rudder failed. I can close haul without rudder but that's about it. Now I have a reserve rudder and a decent autopilot.
.
 

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Over the past year or so I've seen many reports of rudder failures and/or loss in cruising boats. Apart from age and "cycles" like we've talked about in the past, I'm wondering what the cause is. And I'd love to get feedback on this from the great designers we have around here - as well as the salts.

I'll lay out my hunch to get things started, based on my own experience...

Last year the boys and I did a 150-mile offshore delivery of a friend's Pearson 365 in some relatively "rough" conditions. The seas were maybe 3-4 meters, and steep (left overs from a big storm in the Gulf) and winds were in the high 20s. We were, unfortunately, sailing with that stuff just forward of our starboard beam. So, though it was a gentle beating for the most part, it was pretty jumpy and rolly. We were steering with AP.

The next morning things were calming down and we suddenly lost steerage. I grabbed the wheel and confirmed we could still steer, while my friend's son reset the AP - thinking it had just been a glitch. It was fine for a minute or so, then we lost steerage again. I asked him to take the wheel and I opened up the lazarette.

The AP, a ram arm model, had ripped off its base, where it had been bolted, and was rolling around. At least we still had the rudder. We obviously shut down the AP and steered the rest of the trip by hand.

I remember thinking about the fact that there had been a lot of force applied there to rip that thing out. Then I started thinking about all the offhsore races I'd done - hand-steering only - and never recalled feeling that kind of force through the wheel - even in rough conditions.

So, my first question...is AP (especially ram arm versions) a liability in big seas? My hunch is that it is and that is one of the primary causes in these rudder losses we're seeing on cruising boats.

AP is almost continually used by sailors (especially short-handed cruisers) these days on long trips. And it especially used (I think) when things get tough because it seems to be safer than standing in the cockpit steering 24/7.

But when you look at the boat motion in these videos - you see that there is a tremendous amount of lateral force being applied to the rudder:



Now, that is an F10/11 in the second video. If I were unfortunate enough to be caught in that I'm pretty sure we'd already be on a drogue...not pushing the boat like that. I'd be way too scared.

But, you'll notice that in both of these cases, the boat is being hand-steered. It seems to me that this provides a great deal of "cushioning" (response time and give) for the rudder over a mechanical ram.

If your stern is swinging through 20-30 degrees at surfing speed on AP...what kind of force are we talking about on the rudder and stock? It seems astronomical.

I this a cause of the failures we're seeing?
You're way over-thinking this… Rudders fail for a pretty simple reason:

They are not strong enough...

Either in their original engineering and construction, or after having being weakened by repeated load cycles over time… The loss of the rudders on the Catalina 42 JAMMIN', and the Alden 54 ZULU, in last fall's SDR, would seem to be likely examples, respectively… Or, a rudder might have been previously damaged in a grounding or collision, and not subsequently surveyed or properly repaired, as appears to have been the case in the loss of the Beneteau BLUE PEARL in the Atlantic last spring…

If rudder failures are indeed being caused by autopilots, the rudders aren't strong enough, pure and simple… Undoubtedly, many out there are guilty of 'abusing' their steering systems to an unnecessary degree. Most often by sailing to an overpowered or unbalanced sail plan, or sometimes by not adjusting the autopilot's Gain or Rudder Response settings appropriately for the conditions, resulting in unnecessary or inappropriate course corrections… But if any rudder cannot withstand the continuous input from an AP, it's just too damn weak, period…

And, the notion of intentionally installing an undersized AP to act as a sort of 'fuse' seems dangerous to me, and likely to result in more catastrophic events like a broach that might result in a knockdown, or an accidental jibe that might bring down the rig… Anyone who worries about the ability of their steering gear to withstand the forces imparted by either an autopilot or a vane, probably shouldn't be venturing beyond the reach of Sea Tow…

:)
 

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The lateral forces on a rudder are enormous.
A spade designed rudder is going to be a disadvantage.
Personally, I like the long keel with a keel-mounted rudder. It will still have similar lateral loads, but it does not have the same aggressive bending moments that the spade rudder has.

.
Well, I know of at least one fairly well-known yacht designer who might disagree with that…

:)

A properly engineered and constructed balanced spade will steer the boat more efficiently, can wind up imparting far less helm pressure on the other components of the steering system, than a more traditional 'barn door' attached to a longer keel, and further from the end the boat…
 

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On my boat the rudder is built up around a welded frame. I don't know for sure but would assume this is common practice.

Last fall my friend was playing with his new moisture meter and got a "wet" reading on my rudder. Two holes drilled in the bottom drained the water. I sealed around the rudder post after letting it dry out over the winter. But you have to wonder how many older boats have or have had water get into their rudders.

If salt water is in there long enough you'll get corrosion on that subframe, most likely at the welds, the worst possible place. Add cycle stresses and you get a stress fracture and your rudder is spinning around its post - and it's most likely to occur in rough conditions :eek:

Smack have most of the failures been with boats that were older than say 10 years?
 

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Anyone who worries about the ability of their steering gear to withstand the forces imparted by either an autopilot or a vane, probably shouldn't be venturing beyond the reach of Sea Tow…

:)
You think broaching in a storm is worse than losing your rudder in a storm? Okay, but I disagree.

And, I would counter that anyone who doesn't worry about the ability of their boat and steering gear in heavy weather, damn sure better have a good life raft.

I survived twenty eight years of a very hazardous career with only minor injuries because I worried about what could go wrong, not just what I thought would go wrong.

I'm sure that all of the people I worked with who were killed, were 100 per cent sure everything was going to be fine 30 minutes before it happened. Arrogance kills a lot of people (and, nothing personal, but you seem to have it in spades).
 

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I've experienced one steering failure on a Little Harbor when a sheave broke loose from a bulkhead. Luckily this was near shore on a windy day, so the struggle with the emergency tiller (what a joke they are), was of short time duration. It took 2 guys to handle it. The autopilot connected to the quadrant still worked, so we only used the "emergency tiller" near the dock. I cannot imagine steering for any length of time in any sea with an emergency tiller. Maybe it was just a heavy boat, but I'd advise anyone to try it someplace where if they let go they won't hit anything before you need it. And bring some body builders.

One of my friends, same builder, lost a rudder on the stainless stock on the way to Tortola. Broke clean away. Got in towing wraps for 500 miles. Described this setup as a good way to describe a serpentine course. Luckily I wasn't on that trip.

Really to keep sailing only 3 things have to work. Rudder needs to stay on, rig needs to stay up, and any hole in the boat has to be smaller than the rate you can bucket. These systems are worth your extra attention IMHO.
 

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Discussion Starter · #19 · (Edited)
The other part of wind vane steering is that it Will Not steer the boat if you have too much sail up. I wonder how many autopilot failures are the result of continued use in sporty conditions without reduction is sail area. The skippers have no idea of the forces being exerted on the rudder, quadrant, cable and wheels because the electric auto pilot is overcoming those forces....until it breaks.

Pretty common to see the broken arms, fittings and attachment devices on the electric, ram driven autopilots. It would be something I'd be taking a look at before every passage, tightening the brackets, looking for fatigue cracks, etc.
I think this is great point, and is a pretty good summation of what I'm getting at. When the AP is doing all the work, your physical judgement of those forces is out of the loop.

And remember, I'm not talking about the forces YOU feel through wheel necessarily (Med's torque example above), I'm talking about the forces on the rudder/stock/tube itself via the ram arm. Are they any greater than what would applied by hand-steering?
 

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Discussion Starter · #20 ·
Anyone who worries about the ability of their steering gear to withstand the forces imparted by either an autopilot or a vane, probably shouldn't be venturing beyond the reach of Sea Tow…
:)
Oh now....the way I look it is if you can do it, anyone can.
 
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