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Old 23-10-2014, 11:49   #1
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Rudder Failures

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 primary cause is.

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 gusting to low 30s. 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 offshore 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 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 is 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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Old 23-10-2014, 12:40   #2
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Re: Rudder Failures

I've seen 3 brand new boats that had rudder failure. All Beneteaus. Either the chain had broken or the quadrant had become loose.
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Old 23-10-2014, 12:42   #3
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Re: Rudder Failures

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Originally Posted by Draikhyan View Post
I've seen 3 brand new boats that had rudder failure. All Beneteaus. Either the chain had broken or the quadrant had become loose.
Did they have APs? And were they being used at the time of failure?
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Old 23-10-2014, 12:54   #4
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Re: Rudder Failures

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Originally Posted by smackdaddy View Post
Did they have APs? And were they being used at the time of failure?
They were factory equipped with APs (the type for steering wheels) but only one was using the AP when the rudder installation failed. They were brand new boats being delivered to the Caribbean and each manned by an experienced delivery skipper and an inexperienced crew of youngsters. I can still hear the complaints about the short emergency tillers.
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Old 23-10-2014, 12:58   #5
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Re: Rudder Failures

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I'd guess in many cases, corrosion inside the rudder is the cause of failure. We replaced our original rudder because the post was bent, caused by grounding during hurricane IKE. But...look at the rust dripping beneath the rudder. Would have been a matter of time before it failed.

I ordered a new Foss Foam rudder. They built our original rudder for Hunter, and still have the molds. It has served us well so far (2 1/2 years).

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As you know, we don't have an autopilot. I have never noticed significant loads on the wheel when beating or close reaching. However, get the wind and waves behind the beam, and those forces become much more noticeable.

I'm sure there are plenty of cruising boats of all types out there that have had their rudders and steering system (cables or whatever) neglected for way too long. For some, they too will be rudder-less one day.

How are rudders constructed? - http://newrudders.com/?page_id=12

Also from their website - You should make periodic inspections of your rudder to look for possible damage or electrolysis. Left undetected slight rudder stock bends or shaft erosion may lead to failure in heavy conditions.

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Old 23-10-2014, 13:00   #6
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Re: Rudder Failures

Quote:
Originally Posted by Draikhyan View Post
They were factory equipped with APs (the type for steering wheels) but only one was using the AP when the rudder installation failed. They were brand new boats being delivered to the Caribbean and each manned by an experienced delivery skipper and an inexperienced crew of youngsters. I can still hear the complaints about the short emergency tillers.
Very interesting. Thanks Draik.
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Old 23-10-2014, 13:03   #7
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Re: Rudder Failures

Ralph - I'd forgotten about your rudder replacement. I suspect you're right - that the primary cause is corrosion, etc. I was just amazed when that AP ripped out of its base in what I thought were moderate conditions...on a very well-taken-care-of boat.
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Old 23-10-2014, 13:07   #8
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Re: Rudder Failures

There was an article about a brand new boat delivery that had a rudder failure and sank in a Dutch magazine last month. The make and type were not mentioned, but several people have reported that the pictures showed it was a Beneteau Oceanis 45 footer. Shocking, really, that a new boat has such a problem within a 1000 miles of delivery.


Onno
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Old 23-10-2014, 15:10   #9
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Re: Rudder Failures

usually hydraulic auto pilots are mounted on a very short arm as they have short throws, this of course means with so little mechanical leverage that very large forces are in play.
Having a rudder essentially "locked" in place by these type of auto pilots, can I believe lead to fatigue of the rudder or it's post, I think all of us have from time to time felt a "kick" back through the wheel from something, that little kick even though it's not much travel could well significantly reduce forces the rudder is exposed to.
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Old 23-10-2014, 15:21   #10
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Re: Rudder Failures

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Originally Posted by JazzyO View Post
There was an article about a brand new boat delivery that had a rudder failure and sank in a Dutch magazine last month. The make and type were not mentioned, but several people have reported that the pictures showed it was a Beneteau Oceanis 45 footer. Shocking, really, that a new boat has such a problem within a 1000 miles of delivery.


Onno
Come on Onno, you know these boats always suffer damage sometime prior to losing a rudder, it can't have been new from the factory!
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Old 23-10-2014, 15:29   #11
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Re: Rudder Failures

Often a plywood platform is glassed into the hull to hold the ram and they have to be very stout to take the loads. I have seen several that ripped off the base because they were under built.
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Old 23-10-2014, 15:48   #12
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Re: Rudder Failures

I think the some consideration should be given to the notion that the autopilot could have been hiding problems with sail trim. Even on a reasonably balanced rudder, this is going to cause problems sooner or later, as the there would be a constant sideways force on the rudder assembly. Perhaps, in the case of a balanced rudder, this would not contribute to the AP actuator becoming detached, but any imbalance in the rudder might have amplified the forces on the actuator when coming off the side of a wave.

With our big old barn door rudder I got a pretty hard lesson in sail trim on the delivery trip home, though it was months before I figured out what I had done wrong (thanks to the advice of CF members). Thankfully by that stage in the journey our electrics were practically dead so we were not using the AP, otherwise I suspect we would have done some damage to the steering. As it was, as we fell off the front of the bigger waves I was not strong enough to hold the wheel against the force so the system was allowed some relief.

I now keep a close eye on the wheel position marker when using the AP to make sure the helm has not crept round to balance poor sail trim.

Matt
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Old 23-10-2014, 15:57   #13
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Re: Rudder Failures

Quote:
Originally Posted by smackdaddy View Post
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 primary cause is.

(...)
1) poor design,
2) poor maintenance,
3) bad knocks.

A well designed rudder, even when damaged, should neither rip out a part of the hull nor flood the hull, even in the most extreme accidents. In all other cases the boat is not designed for open water sailing.

Read about Dongfeng rudder damage and loss a couple of days ago. They did not even lose the slot. This is how any serious rudder should be built.

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Old 23-10-2014, 16:28   #14
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Re: Rudder Failures

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Originally Posted by smackdaddy View Post

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?
No.

At surfing speed there is hardly any swinging, unless there is free play in an (over) balanced rudder.

The forces are related to how the rudder is designed. A flush boat with a fine spade rudder may need only minor corrections as she surfs. If the rudder stalls, it will be equally easy to turn.

If it is a barn door rudder and the boat is a tub, she will not surf, she will broach. The rudder will not stall. The motor/arm will lock and burn, but before that you have a fuse in the AP circuit that should burn before the motor does.

If something rips off (a quadrant or the AP motor base) then it was not designed/built for the job.

If you have a hydraulic arm, things may break with an overloaded barn doors rudder / locked spade rudder. I am not sure how you fuse a hydraulic system but I bet you can.

The conditions in your video do not look 10/11, they look 8. But if this is the beginning of the show, this is how it looks like. The boat is not surfing yet.

BTW I love your video (it makes me feel like sailing) and your post: we see way to much rudder damage in cruising boats today. You know, people get marina queens and ask them to sail in demanding conditions. This is asking for trouble.

Cheers,
b.
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Old 23-10-2014, 16:40   #15
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Re: Rudder Failures

When the design is set right the forces are very small:



handsteering a surfing 60'er, no wheel.

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