***WARNING*** 2015-18 YAMAHA “AR” BOAT OWNERS WITH FORWARD SWEPT WAKEBOARD TOWERS

[PJ73]

Holy crap. Sorry to hear about that. Hope you're alright. Does the AR210 have the same locking mechanism? Or is this a 230/240 issue? I'm thinking one of the first things I should do is get up under there and put lock tight or a locking washer to keep the tower base in place.

 

[swatski]

Holy crap. Sorry to hear about that. Hope you're alright. Does the AR210 have the same locking mechanism? Or is this a 230/240 issue? I'm thinking one of the first things I should do is get up under there and put lock tight or a locking washer to keep the tower base in place.

This is the best we came up with, so far (TTBOMK)
https://jetboaters.net/threads/2015-ar240-tower-fix.16089/

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[Arcadyus]

Holy shit @swatski I'm glad your ok. Has the tower actually failed on anyone else on the forums? I'm going to mod mine today although it sucks because I do garage my boat and take the tower down every time we use it.

 

[Jonathan Pisarczyk]

Holy shit @swatski I'm glad your ok. Has the tower actually failed on anyone else on the forums? I'm going to mod mine today although it sucks because I do garage my boat and take the tower down every time we use it.

Me too. I'm still debating about the drill thru with pin.

 

[Neutron]

Only one collapse but there have been a few with the screw knobs coming loose.
I have never had a loose knob. I have had the tower down a dozen times.
I am 100% confident with my unmodded tower.
I have approximately 7 threads catching and after beating up the boat in 3 footers for a while i check and neither is loose.

The design problem i only see is that it can be easy to crossthread the bolt. Thats it. If no damaged threads then no issue.
JMHO

 

[2kwik4u]

Holy shit @swatski I'm glad your ok. Has the tower actually failed on anyone else on the forums? I'm going to mod mine today although it sucks because I do garage my boat and take the tower down every time we use it.

I agree with @Neutron , the tower is acceptable in an as designed state. Check your bolts for cross threading, and inspect them for damage and tightness often and you should be in good shape.

I too take my tower down to get in the garage for every single outing. Probably in the range of 40 instances a season that my tower is up/down. This is the end of my second season and I have no damage or failures to report.

This is very much a procedural safety system though, not an inherently safe design. Much like we all agree to drive on the right side of the road, and that procedure keeps us safe, if you don't adhere to a standard process, your risk for an accident goes up. I inspect at several intervals, each time tower is raised, at the beginning of each trip onto the water (we trailer with the tower up, and checking these bolts is part of the pre-launch checklist), at the end of each day on the water for any loosening, and then again when raised back in the garage. By using a proceduralized system I'm mitigating as much of the risk of harm to family, self, and property as possible.

 

[swatski]

Only one collapse but there have been a few with the screw knobs coming loose.
I have never had a loose knob. I have had the tower down a dozen times.
I am 100% confident with my unmodded tower.
I have approximately 7 threads catching and after beating up the boat in 3 footers for a while i check and neither is loose.

The design problem i only see is that it can be easy to crossthread the bolt. Thats it. If no damaged threads then no issue.
JMHO

I agree with @Neutron , the tower is acceptable in an as designed state. Check your bolts for cross threading, and inspect them for damage and tightness often and you should be in good shape.

I too take my tower down to get in the garage for every single outing. Probably in the range of 40 instances a season that my tower is up/down. This is the end of my second season and I have no damage or failures to report.

This is very much a procedural safety system though, not an inherently safe design. Much like we all agree to drive on the right side of the road, and that procedure keeps us safe, if you don't adhere to a standard process, your risk for an accident goes up. I inspect at several intervals, each time tower is raised, at the beginning of each trip onto the water (we trailer with the tower up, and checking these bolts is part of the pre-launch checklist), at the end of each day on the water for any loosening, and then again when raised back in the garage. By using a proceduralized system I'm mitigating as much of the risk of harm to family, self, and property as possible.

I understand what you guys are saying, but at some point I think we will just have to agree to disagree...

The design is either good (safe) OR not so good (not safe).

My unmodified bolt (talking 2016 AR240 tower) engaging by approximately 6-7 threads (full turns counting from the initial engagement) FAILED (wiggled out) within an hour of hitting rough water (went from fully IN to OUT), and so did multiple other handwheel bolts in several AR240s. That is a fact. Some of the owners had the bolts pull out even though they already knew of the issues.

I have modified the bolts which now engage ~14 threads/turns and have not had an issue since (knock on wood).
I would encourage every owner to extend the available thread length as I've posted elsewhere. But ultimately, that is a decision that every owner needs to make for themselves.

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[2kwik4u]

I understand what you guys are saying, but at some point I think we will just have to agree to disagree...

The design is either good (safe) OR not so good (not safe).

We'll have to agree to disagree on this. The design is safe in an undamaged/as designed condition, with proper installation.

My unmodified bolt (talking 2016 AR240 tower) engaging by approximately 6-7 threads (full turns counting from the initial engagement) FAILED (wiggled out) within an hour of hitting rough water (went from fully IN to OUT), and so did multiple other handwheel bolts in several AR240s. That is a fact. Some of the owners had the bolts pull out even though they already knew of the issues.

I have modified the bolts which now engage ~14 threads/turns and have not had an issue since (knock on wood).
I would encourage every owner to extend the available thread length as I've posted elsewhere. But ultimately, that is a decision that every owner needs to make for themselves.

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The additional threading is giving you a false sense of security. The threads in the stock design are fully engaged with the nut, so there is no additional friction added, and no additional load carrying capacity, nor resistance to backing out. You've only added a further distance that it must back out before exiting hte nut completely, which gives some additional time to see the problem happening.

The only reason issues have been seen are damaged bolts, or improper installation. Inspection for damage and proper installation are the only solutions without modification of the entire joint.

NOW, the locking bolt you added to the bottom does help the situation in terms of additional forces to keep the bolt from backing out, however it completely defeats the purpose of a folding tower. A problem for some (myself), and not for others (yourself).

For those wanting to read more about bolted joint design here are some links

https://www.eng-tips.com/viewthread.cfm?qid=35222

https://www.eng-tips.com/viewthread.cfm?qid=257201

https://www.engineersedge.com/ansi_hardware_menu.shtml

https://www.engineersedge.com/material_science/bolt_single_shear_calcs.htm

 

[Benoit]

Hi. Sorry to hear of this problem. You can drill a shallow hole in the side of the bolt where the threads are engaged then melt melt some plastic in it. Make sure the plastic is above the minor of the thread. This creates a locker that is removeable

 

[LukePrinsloo]

I'm in agreement with @2kwik4u A fully engaged bolt only applies pressure to a certain number of threads. It's been a decade since I took the course but If I recall only 3 threads are required to generate the tension. Due to tension lengthening of the bolt during torquing only the threads closest to the application "see" any load, the rest of the threads are clear. Now if the threads closest fail, the threads further out will carry the load.

Thanks to this thread I actually checked my bolts and found one to be loose. I'll keep an eye on it for sure.

 

[2kwik4u]

I'm in agreement with @2kwik4u A fully engaged bolt only applies pressure to a certain number of threads. It's been a decade since I took the course but If I recall only 3 threads are required to generate the tension. Due to tension lengthening of the bolt during torquing only the threads closest to the application "see" any load, the rest of the threads are clear. Now if the threads closest fail, the threads further out will carry the load.

Thanks to this thread I actually checked my bolts and found one to be loose. I'll keep an eye on it for sure.

Rule of thumb is 1.5x Major Dia of bolt. Number of thread depends on pitch of bolt.

If nothing else I hope these discussions make every single tower owner inspect that connection on a regular basis.

 

[spatty99]

I think the tower retention design is inferior, and there are clearly superior alternatives. It may be technically functional under ideal conditions, but it fails to account for some critical issues. For example, tolerance and/or material issues (corrosion, creep, etc.) can lead to cross threading and thus total failure. Additionally, the extreme vibrations on boats require accommodations beyond the typical calculations. In the current design, a pull out bolt should have better means of retention (e.g. double nut, retaining loop). Better yet, utilizing a bolt in shear (like the other towers) would completely eliminate dependence on the threaded connection.

 

[swatski]

The design is safe in an undamaged/as designed condition, with proper installation.

Again, I understand the argument, but I think you guys are missing the point: a safe design is a design that is robust.
Not just safe under ideal conditions.
This design is NOT robust as indicated by repeated failures in several (distinct) towers.

The additional threading is giving you a false sense of security. The threads in the stock design are fully engaged with the nut

This is simply not completely correct. The female thread does have 6-7 threads but those are not fully engaged as the bolt comes in short, at least that had been the situation in my tower and at least one other tower (in the picture, below - not mine):

(please ignore the black arrow, that's from a different discussion of powder coat)

An "elongated" bolt, as in my mod, engages more securely as it goes past the end of the female thread - into a "cavity"/space inside the base bracket, ascertaining full available engagement, there is no question about it.

I agree the design is okay and will do IF one is aware of the problem and constantly monitors the bolts. Is that what I would call "safe"... Not sure. Robust it is not.

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[Stevenpigsooie]

The AR tower design is cheap and definitely not robust. I have never lowered my tower and bought my boat new and roughly every third trip out I get a 1/8 to 1/4 turn on one of the bolts during my prelaunch check (that I added after @swatski tower incident). Actually next time out think I will apply a little removable locktite.

 

[2kwik4u]

I think the tower retention design is inferior, and there are clearly superior alternatives. It may be technically functional under ideal conditions, but it fails to account for some critical issues. For example, tolerance and/or material issues (corrosion, creep, etc.) can lead to cross threading and thus total failure. Additionally, the extreme vibrations on boats require accommodations beyond the typical calculations. In the current design, a pull out bolt should have better means of retention (e.g. double nut, retaining loop). Better yet, utilizing a bolt in shear (like the other towers) would completely eliminate dependence on the threaded connection.

Corrosion is an issue to be watched, but typically won't contribute to cross threading. Creep is only a concern under elevated temperatures (750deg+ for SS, around 450deg+ for mild steel). Tolerancing and general bolt quality is a concern. A Grade 8 fastener (or metric equivalent) would have been nice to have, but not 100% necessary).

Extreme vibrations due tend to cause reason for extra examination. It typically manifests itself in the calculations as increased load (because it's no longer just gravity supplying the force, the cyclical nature of vibrations create additional "G" loading), OR increased safety factor to stay below the fatigue limit of the metal in question. Mild steel is typically a 60ksi yield, with a fatigue/endurance limit somewhere in the 44ksi range. Bolt grades can vary this a little, but those are some general rule of thumb values.

This bolt setup is loaded almost completely in shear. I'll have to look at my hand calcs when I get home on Friday to find the loading percentages. Another reason why we haven't seen a single instance of the threads pulling out, but only of the bolts themselves backing out. That alone should indicate that the loading on the bolt, threads, or any other portion of the apparatus is well within safe limits. If anything, we can see that the shock loading from the experience @swatski had still did not break/bend the bolt, or pull the threads out. It wasn't until BOTH bolts were completely removed from the threads that the tower collapsed and caused harm to persons/property.

The issue at hand is thread locking, not strength of bolt, nor number of threads, nor the means for which to increase either of those. A simple anti-rotation tether (similar to safety wiring bolt heads) would prevent 100% of the safety concern IMO. As would thread locking compound, patched fasteners, set screws, or any other form of anti-rotation device.

As to if this design is a "good" or "robust" design; that's such a subjective set of words that can't be quantified, and as such makes it opinion. Correct installation and utilization is critical in any number of things we interact with on a daily basis. Some have more risk than others attached to them. The only problem with this design IMO is the lack of education in the manuals/stickers on the boat. Another two warning stickers on the tower would probably be sufficient to alert the user of the dangers of an improperly seated tower.

 

[J-RAD]

I fear we're awaking a beast again... I'm going to throw in anyway. Mine is one AR tower that is up and down twice each outing for storage. I'm now wrapping up my third season with it. I've never experienced any failure or signs of such and I FEL little concern about it doing so.

BUT... I think the one argument that matters here is that despite all the rebuttal, the design of the tower it HAS failed at least once and shown symptoms of potential failure on multiple other occasions. Throw all of the engineering mumbo jumbo you want at it, or HAS happened. If it were truly well designed and safe it would eliminate the possibility of such instances. There are many cases that have proven the potential for creep and have necessity of consistent human input to ensure it isn't working it's easy loose. The design is mostly adequate, but is enough to eliminate risk...? It seems to leave a margin for error that allows for an instance like @swatski experienced to occur. From what he's described, he was not negligent, he was attentive to his tower prior to embarking and did at least the minimum of what should be required to ensure the security of his tower.

So despite what your engineering background is telling you, the real world application is another story. Is it negligent on the ETP or Yamaha...? I'm certain it wasn't intentional, their engineers all thought it was adequate for the application. What risks is acceptable? How much responsibility should be put on the user? It'll be interesting to hear the outcome of the @swatski litigation. (Any update?)

So, we can go back and forth bickering over adequacy for days as 21 pages of this thread have. Or move on either accepting the responsibility and risk that does exist or do something about it as @swatski has. Waiting for Yamaha to come up with a solution to a problem they deny many keep you waiting...

I think there is one thing we can agree on. There is a better way of doing it than the current application.

Namaste

 

[Jameson Clark]

While I see both sides of this argument. I like the pin style on my boat much better than the screw in design. Simpler, yet stronger system in my opinion and also easier to raise and lower the tower. Since Yamaha has both designs, the fact that they are still using the inferior (in my opinion) one is what boggles my mind.

 

[spatty99]

It is certainly well established that the textbook engineering loading analysis of the bolts are well within reasonable limits. But that is a narrow focus that ignores other complicating factors (discussed in subsequent chapters of said engineering textbooks), which are clearly an issue given actual failure(s). And, there are better designs in use that completely eliminate the risk... no warning stickers necessary.

 

[swatski]

The issue at hand is thread locking, not strength of bolt, nor number of threads, nor the means for which to increase either of those. A simple anti-rotation tether (similar to safety wiring bolt heads) would prevent 100% of the safety concern IMO. As would thread locking compound, patched fasteners, set screws, or any other form of anti-rotation device.

That is correct. I came up with a solution that I refer to as a "part two" in my fix.
There are other way to accomplish that of course, but unfortunately none taken by the OEM.
My "fix" is very low tech and has drawbacks, but seems to work well as far as preventing a pull out.

As to if this design is a "good" or "robust" design; that's such a subjective set of words that can't be quantified, and as such makes it opinion. Correct installation and utilization is critical in any number of things we interact with on a daily basis. Some have more risk than others attached to them. The only problem with this design IMO is the lack of education in the manuals/stickers on the boat. Another two warning stickers on the tower would probably be sufficient to alert the user of the dangers of an improperly seated tower.

I think you are completely missing the point.

"Robust" is not a subjective word/definition here. It implies ruggedness that can only be revealed in relevant field tests necessary to back up any mechanical design's theoretical considerations.

Any mechanical design is only as good as its field testing reports.

Most mechanical failures in boating, car industry, and space exploration are NOT due to a lack of theoretical considerations. In case of the AR240 tower, the design is actually robust for pulling/towing objects but fails (repeatedly) where it matters most - cruising in rough water.

Even the best thought out/brilliant designs can fail rigorous field testing. Yamaha used to test their boats and towers as documented in at least one 2008(?) leaked factory video. There is no question in my mind that that kind of testing would reveal the need for improvements in the 2016 model AR240 tower locking mechanism.

I'm not saying that leaving it as it is from factory is a mistake. To each his/her own.
If you have the time and the attention span to keep a watchful eye on the tower locking wheel-bolts - by all means do it!
If you leave the boat in someone else custody, be it a dealer, don't forget to carefully examine the threads keeping in mind the risk of cross thread which may not be obvious to an untrained eye.

In regard to your "correct installation and utilization" comment, I do not actually know what that is... Your statements in that regard may be correct but are not backed by anything in the operator manual.
What I do know is that these bolts back up in different boats on a regular basis. What else do I need to know not to be worried???????

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[swatski]

It'll be interesting to hear the outcome of the @swatski litigation. (Any update?)

Yes, it's done. It's been an interesting experience, I'd rather not go any further than to state costs of fixing damages have been covered.

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