Steering Issue


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We haven’t had steering issues in the past. Given they can happen anywhere, why the heck would it occur within hours of dead-center on our 2,800 nm trip through the North Atlantic?

We have covered a lot of miles over the years and generally have seen pretty good conditions. The weather we’ve encountered has been just serious enough that we are never tempted to get complacent, but we generally get good weather and don’t see frightening conditions. This trip has already offered up the most difficult situation we have yet faced at sea.

Last night around 8pm I noticed black metal dust under the rudder arm, pictured above, and it appears the rudder has as much as 3/16″ of play when it should have none visible. Likely this is still fallout from the two days of unusually rough weather. The mechanical parts that make up the rudder assembly are one of the few areas where we really wish we had more redundancy partly because it’s hard to continue a trip without a rudder and partly because the mechanical loads at the rudder arm are massively high. With loads that high, everything needs to be both designed right but also in excellent operating condition. The pile of metal dust has me nervous so I decided to wake Jennifer up and go after this issue immediately. We stopped the boat so we could work on the rudder with lower hydrodynamic loads on it. Immediately we learn how much we love ABT stabilizers.  The water is by no means rough out there, but without active stabilization, we do move around quite a bit. I took the rudder arm bolt out to find the source of the rudder dust.


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The rudder arm to steering ram attachment is apart and pictured above. It was worse than I was guessing by the amount of dust. The rudder bolt securing the rudder arm to the hydraulic ram is already heavily worn.  Prior to the period of really rough water we just went through, there was no evidence of metal dust at this location—this happened surprisingly quickly. My first theory was that the rudder had seized up and overload is causing this massive wear. But I could swing the rudder by hand using a large adjustable wrench, so that didn’t appear to be an issue. It still might be the case that it locks up under heavy hydrodynamic loads. But it seems likely that if I am strong enough to swing the rudder with an adjustable wrench, it’s probably fine. Unfortunately, the bolt is destroyed. We have a pretty extensive set of spares, but it doesn’t include this one. The closest thing we have is a keel through-bolt, but it is much too long and not quite thick enough.

The nut that tightens up this assembly threads onto the bolt to a fixed location drilled through the nut and bolt when the boat was built. A cotter pin is placed through this assembly so it can’t back off. Nice design, but it does mean that there is one level of tightness where the cotter pin goes through and no other options. My theory is there has been wear throughout over the years—not enough to show free play but just enough wear that the bolt can work back and forth in some conditions. In the rough water where the waves were as high as 20 feet, the steering ram was working hard and fast and, with this small flex, we took a lot of wear. I wish I had seen it earlier before giving up as much metal as we have. Still 90% of the bolt is still there and that should be plenty if we can stop the movement. I added some washers to force the hydraulic ran rod end down slightly on to a less worn section. Then I tightened the nut up to about 60 ft lbs. In the next picture you can see where we ended up on this temporary fix.


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The system was back together. The good news was the assembly was tight and didn’t appear to be flexing, but the bad news was that, as we tighten to take up this play, the cotter pin hole no longer lines up and so there is no way to secure the nut and prevent it backing off. We’d have to find a way to deal with that.

We put the boat back on track and brought it up to full speed to see how stable the assembly was. The test isn’t great because we are in relatively flat water but we are running near full speed and there is no evidence of flex or play. Jennifer really scored and was able to round up a nut of the right size and thread which may actually help save this situation. I used the second nut with Loctite red as a lock nut. The second nut is run up against the first nut tight so neither can move. The assembly appears secure but the real test is do we get flex, play, or metal dust over the next 12 to 24 hours?  We’ll watch it closely and ensure we don’t give up any more metal before making changes. We’ll just keep trying different things if needed. Airplane travel is starting to have a certain appeal 🙂

 


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33 comments on “Steering Issue
  1. Colin Rae says:

    Thanks James.

  2. Steven Coleman says:

    Hello James,
    You two are certainly having issues this trip. Nice thing is you are working through them.

    Looking at that bolt it would appear to me that the load bearing surface of the Heim Joint was resting (at least partially) on the bolt threads.

    As you know, that’s not a big deal as long as nothing moves however, once it does those threaded parts are going to wear quick.

    Have you considered a slightly longer bolt with more “shoulder”? You could have the threads extended if it was going to require to much in the way of washers.

    Maybe even insert it from the bottom up so the nuts could be “witness” marked and maybe spotted more easily if something started to back off?

    • As always, good suggestions Steve. Overall, I think the bolt has quite a large safety margin when it comes to overall strength. I agree it would be better with a longer shoulder but the key mistake here was it not being sufficiently tight. It was delivered nice and snug with a cotter pin through the assembly. I always do it up exactly the same but, over time, it’s gotten slightly less tight. Even then it mostly didn’t matter but in the couple of days of unusually rough seas, the bolt started to move. Once it was moving, it wore fast, loosened more, moved more, and wore even more quickly. I’ve stopped using the cotter pin and will just double nut the assembly and I expect it’s a problem we won’t see again.

      I agree that a witness mark is a good idea.to catch any movement early.

      • Steven Coleman says:

        I’m sure by the time you get done it won’t be a problem again or, if it is you’ll have spares on board to deal with it.

        One other thing I noticed from the picture, which pictures can be decieving, is that it doesn’t look like the heim joint is aligned inside the washers (possibly from damage?). Additionally, it could be the picture but it seems the tiller bar is slightly higher than it needs to be and the hydraulic ram is not horizontal.

        Anything you can do to keep everything perpendicular is going to lower the load during operation. It “looks” like maybe the rudder bar where it attaches to the rudder post could be lowered. The heim joint if what I’m seeing is not from damage should just be a matter of loosing the jamnut and turning.

        • Steven Coleman says:

          You do have a spare bolt which, pretty much guarantees your temporary fix will see you through.

        • Steve, if you mean rotationally aligned, the heim join if on the end of a floating rod so it just finds a place possibly 100% aligned and possibly not. The heim joint, rod, and piston can be freely rotated and so that isn’t an issue. The piston, rod, and heim joint float free in rototation. If you are talking about alighnment of the hydraulic cylinder with the steering arm and whether they are in exactly the same plane, that is super important for the reasons you outlined.

  3. Rob says:

    Hello James & Jennifer –

    You two have certainly been challenged this trip but have done an excellent job in keeping Dirona motoring east.

    You mentioned that air travel has its perks, but it is not an adventure like you two are experiencing. This past winter I flew from Boston to London in five hours and twentyfive minutes. I could have flown faster than MACH .80, but due to turbulence I kept the jet at that speed. Fast trip, but not the amazing and brave mission you two are currently on.

    Thank you for the awesome updates.

    Best………..Rob

    • Wow, a MACH 0.80 pass is excellent time Rob. High altitude winds were being kind to you.

      This trip has has more adventure than we aimed for but, overall the boat is running great. We need to do some work at that locker to seal out sea water and I’ll need to change the bolt at the steering arm but, other than that, all is good. We plan to change the main engine oil today since it’s been roughly 250 hours since the last change. We also plan shift from eastern time to the destination time zone today — it’s kind of arbitrary when we decide to change but today feels like a good day to get onto local time — it’s a bit weird to be seeing daylight at 3am.

      We’ll follow your lead and Dirona safely below MACH 0.8 for the remainder of the trip 🙂

  4. Paige says:

    The loss of rudder control is one of my worst nightmares. I have plans to use a shortened Jordan drogue on an adjustable bridle if that should ever happen to me. I’m sure you have ideas James, if you have something with more finesse in mind, I’d really like to learn from you.

  5. Paige says:

    Paige joins James, in adding a couple of spare bolts for the steering ram to the spares., asap.

    • Yes, you are right Paige. I’ve been slightly annoyed with myself for not having an appropriate spare to what is a mission critical part. We are stocked fairly deeply. You’ll laugh but we actually do have a spare bolt and nut. Normally the way parts storage work on Dirona is I remember what we have and Jennifer looks up where it was. I didn’t remember buying this one. But last night Jen looked it up anyway, wow, we do have a spare. The old one is doing well and not moving at all now that it is torqued up properly. Even with all the lost metal, it’s doing great.

      Having now spent a few days watching the wear on this part carefully and kicking myself or (supposedly) not having one, I will buy another one to serve as a spare. This is one of those parts that is unlikely to fail but, if it does, it’s really a big problem.

  6. Rod Sumner says:

    James
    In a previous conversation on steering arm assembly we discussed wether to lube the fitting or leave it
    Based on my experience in abrasive plants assembled dry. Is this the same issue??
    If mechanically you can use a smaller diameter bolt a tungsten carbide sleeve would last
    Just tkinking
    Smooth seas

    • I did change the rod end (spherical bearing) some time back and it appears to be fine. I beleive what is happening here is, if the bolt isn’t sufficiently tight, there is shifting at the bolt even with a good bearing and these tiny shifts just slowly chews away the bolt. The yard tightens these up properly when built and then drills a hole though nut and bolt for a cotter pin at the “right place.” Over 8,900 hours the “right place” changes slightly and this bolt effectively becomes looser over time. Eventually it starts to move, then it starts to wear, then it moves much more, and quickly there is a very big problem. The solution appears to be torque it up and double nut it to prevent the main nut from backing off.

  7. Steve H says:

    James, It looks like your Heim Joint failed and ate the bolt. Your a long way to a parts store. Best of luck on the remainder of your trip.

    • Steve, I thought the same as you but the Heim joint (spherical bearing in the rod end) is actually fine. It’s counter intuitive but if the bolt isn’t sufficiently tight, there is shifting at the bolt even with a good bearing and these tiny shifts just slowly chews away the bolt. The yard tightens these up properly when built and then drills a hole though nut and bolt for a cotter pin at the “right place.” Over 8,900 hours the “right place” changes slightly and this bolt effectively becomes looser over time. Eventually it starts to move, then it starts to wear, then it moves much more, and quickly there is a very big problem. The solution appears to be torque it up and double nut it to prevent the main nut from backing off. Even with the badly damaged bolt in there right now, it’s working well.

  8. John Hammond says:

    James — a Castle Nut may be a good long term solution once you reach port.
    Good thing you didn’t have to deal with this at the same time as the bilge pump issue !

    • Yes, absolutely, that would work much better than one with a single hole for a cotter pin. No question. There is space for a double nut so I may just torque it up and double nut the assembly.

      • Greg Moore says:

        I was thinking either castellated nut or a nut with a safety wire hole drilled. Both approaches work well in the aviation world and I’ve never seen an aviation fastener with a single hole for a cotter pin.

        • I agree the single hole solution for a cotter pin was a poor choice. I shouldn’t have “believed it” and kept using the same hole as the boat has been used over the years. It’s just subtly been getting slightly less tight over time.

  9. Jamie says:

    They say bad things come in threes, I think you guys are clear now for the rest of the trip!

    • In many ways, we shouldn’t be complaining. We only have 1,274 miles to go, the boat is running like a champ, the currents are often helping us, we have plenty of fuel and we’re currently running at 8.9 kts. All is good. But, even with all that goodness, it’s still been a tiring trip — I’ve never seen so many issues. We’re bringing together plans to deal with them all and so shouldn’t ever see a repeat. I’ve never had to wake Jennifer up during her sleep period and I’ve never needed to be woken up during mine. We’ve managed to do both on this trip.

      All is good right now. We have an oil change due sometime over the next couple of days. Hopefully we’ll get some nice conditions to do a quick oil change.

  10. Les Dobbe says:

    Nice catch on the rudder post James! If you have any kind of metal tubing you may be able to create a bearing, similar to a rod or main bearing, which if split into halves it may take up the slack with some “fitting”. Keep the faith it’s all downhill from here 🙂

    • Thanks Les. In this case, the rod end on that attaches to the steering arm is a spherical bearing. Rather than helping the rod end rotate more freely on the bolt, what we need is to prevent it from moving. When the boat was built it was done up tight and a hole was drilled through the nut and bolt to install a cotter pin so it can’t loosen off. I think what was tight 8,900 hours ago is not “not quite tight enough” and in the heavy seas we saw the bolt was wearing when it should have been taking lateral load but not moving. It’s done up to about 60 ft lbs right now and it’s actually doing surprisingly well even as worn as the bolt is. I’ll keep a close eye on it.

      • Timothy Daleo says:

        Maybe drill out a socket or something if it gets worse.

        • The damaged bolt is torqued up properly and doesn’t appear to be shifting or wearing at all. This issue appears to be 100% caused by insufficiently torqued steering ram to steering arm bolt.

      • Jonathan says:

        I agree with the above notes – a castle nut would give you adjustment options and flexibility, and some type of wear sleeve is another option to consider.
        Do you carry an assortment of bolts with you, or just certain sizes you are more likely to need?

        • We carry a vast quantity of spares but a 3/4″ grade 8 bolt that is 3.5″ long is sufficiently special purpose that it’s not in our generic parts collection.

          • Scott Bailey says:

            James, long time reader first time poster. Amazed by your and Jennifer’s adventure so far, including the recent problem solving of the mid Atlantic emergency.
            The benefit of hindsight is a wonderful thing re spares, but failing that, on a mission critical part, why would this bolt not be in a high grade stainless (for hardness) or at least a Grade 10.9 standard bolt? Would you consider swapping out for this?
            Also, if the rubbing issue is more to do with tightness of assembly, could you not extend the bolt length in order to apply two locking nuts to be absolutely certain? (I have OCD!)

            • The bolt is a 3/4 10 thread per inch grade 8 bolt at 3.5″. As you know, higher grades bring increased hardness but also bring increased brittleness. In this particular case, I think the existing bolt probably already has a lot of engineering safety margin as long as it’s sufficiently tight. If not tight enough, there will be wear. Higher grade steel would absolutely help but, if it’s properly torqued and not moving, I think either is fine. Grade 10s are hard to find.

              Last night Jennifer looked it up in our spares catalog and we actually do have a spare. The way we normally work is remember what we have and we consult the parts catalog to find where it is actually stored. In this case, I completely don’t remember getting the spare but it looks like we have one.

              In the case, the source of the problem was the yard torqued the nut on correctly and drilled a single hole through the nut and bolt to for a cotter pin at the “right” location. After 8,900 hours the right location was no longer right. It has slowly become less tight. This allowed some motion, which allowed wear, which allowed increased motion, which produced aggressive wear we were lucky to see in time. The simple solution here is to ignore the original cotter pin hole, torque up firmly so there is no movement, and double nut or Nyloc to prevent loosening. I’ll get another spare nut and bold, install this one, double nut it, and expect it’ll not need any service for thousands of more hours.

              • Chasm says:

                Another thing to consider before changing bolt grade is the hardness of the other materials in the joint.
                It is usually *much* easier to replace a worn bolt than a worn bushing/bearing.
                Which is something to check in port. Did the bearing wear, is it out of round?

                Perhaps add a roll of shim stock to the parts arsenal. That way there is an option to reduce movement between worn parts until a more permanent solution is possible. Say brass because it is easy to work with, soft enough that it does not add to the problem, no issues with rust either.

                • That’s a great idea to have some shim stock on hand Chasm. A nice additional tool to keep things working through problems. I’ll add that to my list.

                  In this case, the spherical bearing appears to be in good shape and both nice and free and with no obvious play. What I believe is happening is there are very large lateral forces in play where the steering arm and the hydraulic ram rod end are 1 above the other held together by a bolt. If the assembly is tight the forces get transferred through correctly without motion. If the bolt is not tight the high latteral forces with the offset cause some flexing and this leads to rapid wear. The reason it was loose is that, when built, it was tightened correctly and then a single hole was drilled through the nut and bolt for a cotter pin. I continue to use the same exact location but, over the course of 8,000 hours, this “correct” location gets subtly looser over time.

                  My plan going forward is to always torque it up firmly and use a double nut to prevent backup rather than a cotter pin in the original hole. I’ll pick up some shim stock as well. Thanks,

                  • Colin Rae says:

                    Hi James and Jennifer,

                    What is the final solution you employed? I am interested because yesterday in large seas on my N47 I noticed the exacts same problem developing!

                    Many thanks,

                    Colin

                    • The issue is caused by the original installation using a single drilled hole through the bolt and nut for cotter pinning. This works well in preventing the nut from backing off. However, over time as the system wears, the cotter pin location, will become insufficiently tight. Once the nut and bolt assembly isn’t tight enough, it’ll flex and begin to wear. As it wears, the assembly will move more and wear will accelerate.

                      The solution is fairly simple: replace the nut and bolt with grade 8 bolts, torque to grade 8 bolt specs, and use a second lock nut to prevent backing off. New equipment properly torqued will operate as designed. It’s a cheap fix and I bought some spares as well.

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