Ar240 Tower 2015+

[swatski]

The issue with the AR towers is not so much the tower weight as the risk of cross-threading those handwheel bolts that hold it up. There is too little thread that engages to start with, it can only get worse with repeated folding and raising. Doesn't have to be the owner, it could be a helper in a dealership, they will often need to fold those towers to move the boats around the place (but yes, Yamaha will blame you if something happens).
I would highly recommend this mod, I have not had any issues since, not even a suggestion of the bolts' loosening up.
Even a partial mod - just the first part (extending the usable thread) makes a big difference.
https://jetboaters.net/threads/2015-ar240-tower-fix.16089/

BTW - this is only the problem with AR towers, the LS and X towers appear safe with their locking cross-pins, much better design.

--

 

[2kwik4u]

I, personally, can't use the second half of that mod as I lower/raise my tower at least twice for each use (to get out of, and in to, the garage), I often lower it on the water to get under a bridge as well. The first half is no harmful, but excessive, as any threaded connection relies on fewer than 2 full threads for holding power unless torqued to yield or made to financially prohibitive high tolerances. I actually have some reason for pause with the modification of the hand knobs due to the thinning/removal of the material interface with the tower itself, and not knowing what head style is underneath that plastic. If there is sufficient metal under that head to hold the tower if the plastic fails then I'll retract that. I simply don't know whats under there.

There is plenty of thread in the "as manufactured" state. The loads are not overly high on those bolts, and very little of that is in tension, most is in shear. The bolts are sized appropriately for the load with adequate safety factor in my opinion. I ran the numbers myself to verify after @swatski had his bad experience with them, and before I took the family out again sitting underneath it. I'm fortunate to have the education/experience to perform the structural analysis on my own. My opinion is that the AR towers are safe in an "as designed and built" state.

The larger and more prominent risk in this design is the relative ease at which they are cross threaded. I've almost done it a time or two myself, and I've been turning bolts since I had baby teeth. If you aren't paying close attention when raising the tower, and then attempt to force the issue of improper thread engagement, you'll cross thread those hand knobs in a hurry. Once cross threaded the ability for the threads to attain a mechanical/geometric "lock" is greatly diminished, resulting in them backing out under vibration. This is made worse by, again what is in my opinion, poor fixturing of the tower bases from the factory, OR poor fixturing of the tower at that manufacturing facility. My tower is noticeably narrower at the attachment points than the bases are set. When raising the tower and inserting the hand knobs I have to "push" the tower outboard slightly to ensure that the threads are started straight/true.

What is lacking in this design is owner/dealer education on the critical detail of the hand knobs NOT getting cross threaded. Secondarily, there are more appropriate (and not cost prohibitive) designs that can be easily implemented to avoid safety issues should those bolts become cross threaded, and want to rattle loose in an obviously vibration prone environment. Even adding a safety cross pin between the base and the tower alone would cost only a few dollars more and increase the margins for error significantly.

 

[swatski]

I, personally, can't use the second half of that mod as I lower/raise my tower at least twice for each use (to get out of, and in to, the garage), I often lower it on the water to get under a bridge as well. The first half is no harmful, but excessive, as any threaded connection relies on fewer than 2 full threads for holding power unless torqued to yield or made to financially prohibitive high tolerances. I actually have some reason for pause with the modification of the hand knobs due to the thinning/removal of the material interface with the tower itself, and not knowing what head style is underneath that plastic. If there is sufficient metal under that head to hold the tower if the plastic fails then I'll retract that. I simply don't know whats under there.

There is plenty of thread in the "as manufactured" state. The loads are not overly high on those bolts, and very little of that is in tension, most is in shear. The bolts are sized appropriately for the load with adequate safety factor in my opinion. I ran the numbers myself to verify after @swatski had his bad experience with them, and before I took the family out again sitting underneath it. I'm fortunate to have the education/experience to perform the structural analysis on my own. My opinion is that the AR towers are safe in an "as designed and built" state.

The larger and more prominent risk in this design is the relative ease at which they are cross threaded. I've almost done it a time or two myself, and I've been turning bolts since I had baby teeth. If you aren't paying close attention when raising the tower, and then attempt to force the issue of improper thread engagement, you'll cross thread those hand knobs in a hurry. Once cross threaded the ability for the threads to attain a mechanical/geometric "lock" is greatly diminished, resulting in them backing out under vibration. This is made worse by, again what is in my opinion, poor fixturing of the tower bases from the factory, OR poor fixturing of the tower at that manufacturing facility. My tower is noticeably narrower at the attachment points than the bases are set. When raising the tower and inserting the hand knobs I have to "push" the tower outboard slightly to ensure that the threads are started straight/true.

What is lacking in this design is owner/dealer education on the critical detail of the hand knobs NOT getting cross threaded. Secondarily, there are more appropriate (and not cost prohibitive) designs that can be easily implemented to avoid safety issues should those bolts become cross threaded, and want to rattle loose in an obviously vibration prone environment. Even adding a safety cross pin between the base and the tower alone would cost only a few dollars more and increase the margins for error significantly.

I can't tell if you are being completley serious here...

Let me ask you this:
How would an average owner know when are those bolts starting to get cross-threaded/out of specs - vs working fine?
There is zero information in the manuals (owner or shop) regarding torque values, tolerances, any specs...
What exactly would you measure to determine your tower locking bolts/mechanism is safe and not going to wiggle out on you?

While I don't doubt you "have the education/experience to perform the structural analysis on my own", keep in mind you are not necessarily the only operator of that tower. By the time you purchased your new boat that tower might had been lowered and raised a dozen times. So, even if you had never taken it back to the dealer, do your own service etc., the damage could had already been done. No?

Not trying to be facetious but you are making claims that are a little confusing, to me:

My opinion is that the AR towers are safe in an "as designed and built" state.

The larger and more prominent risk in this design is the relative ease at which they are cross threaded. I've almost done it a time or two myself, and I've been turning bolts since I had baby teeth. If you aren't paying close attention when raising the tower, and then attempt to force the issue of improper thread engagement, you'll cross thread those hand knobs in a hurry. Once cross threaded the ability for the threads to attain a mechanical/geometric "lock" is greatly diminished, resulting in them backing out under vibration.

So, is it good design? Or not so good design?

Considering those bolts have now been reported to pull/wiggle out in at least a dozen cases, what are the options?
How does one know that thread is getting out of wack?

The OEM bolts can be replaced but can't buy the base (with female thread), it is one part with the tower...

Not trying to be argumentative, but I think this is a serious problem, it's probably good letting others know and beware.
(I wish I had known about this issue!)

--

 

[swatski]

The larger and more prominent risk in this design is the relative ease at which they are cross threaded. I've almost done it a time or two myself, and I've been turning bolts since I had baby teeth. If you aren't paying close attention when raising the tower, and then attempt to force the issue of improper thread engagement, you'll cross thread those hand knobs in a hurry. Once cross threaded the ability for the threads to attain a mechanical/geometric "lock" is greatly diminished, resulting in them backing out under vibration. This is made worse by, again what is in my opinion, poor fixturing of the tower bases from the factory, OR poor fixturing of the tower at that manufacturing facility. My tower is noticeably narrower at the attachment points than the bases are set. When raising the tower and inserting the hand knobs I have to "push" the tower outboard slightly to ensure that the threads are started straight/true.

What is lacking in this design is owner/dealer education on the critical detail of the hand knobs NOT getting cross threaded. Secondarily, there are more appropriate (and not cost prohibitive) designs that can be easily implemented to avoid safety issues should those bolts become cross threaded, and want to rattle loose in an obviously vibration prone environment. Even adding a safety cross pin between the base and the tower alone would cost only a few dollars more and increase the margins for error significantly.

I agree with this ^^^^. Pretty much 100%.

--

 

[2kwik4u]

I can't tell if you are being completley serious here...

100% Serious. No sarcasm, shenanigans, or ballywho intended

Let me ask you this:
How would an average owner know when are those bolts starting to get cross-threaded/out of specs - vs working fine?

There is an obvious difference in feel to a cross threaded bolt as compared to a normally threaded bolt. Running torque could be measured as well. The hand knob should not be used to "pull down" the tower, but only to tighten against the tower once in the fully "up" position. There are enough threads engaged in my experience (limited to two boats) that you can tell if it is a "free running" thread, or if the thread is damaged. Measuring running torque, visual inspection for damage, and "feel" are the only way to measure this.

There is zero information in the manuals (owner or shop) regarding torque values, tolerances, any specs...

Correct, and this is a problem

What exactly would you measure to determine your tower locking bolts/mechanism is safe and not going to wiggle out on you?

IMO if the threads are free running until tight against the tower, then a proper torque should be specified. I use "damn hand tight" for my torque setting, however including a hex head and tool from the factory would go a long way in clarifying how these are supposed to operate and be safe. A well torqued and loaded bolt will inherent not "wiggle out" under use. Damaged threads, under torquing, or improper seating will all aid in that bolt backing out, as you've experienced first hand.

While I don't doubt you "have the education/experience to perform the structural analysis on my own", keep in mind you are not necessarily the only operator of that tower. By the time you purchased your new boat that tower might had been lowered and raised a dozen times. So, even if you had never taken it back to the dealer, do your own service etc., the damage could had already been done. No?

You are exactly correct. Currently I am the only operator of my tower at this point. The dealer I use has high bay doors and doesn't have to lower the tower when it's there. I was fortunate in that it was not damaged before I received the unit, and has not been damaged since. I think others (including yourself) have not had this good fortune.

Not trying to be facetious but you are making claims that are a little confusing, to me:

So, is it good design? Or not so good design?

My point in the post was not to say its a good design or bad, merely that in an as designed state it doesn't have structural deficiencies. To say that all AR forward swept towers are faulty is incorrect. To say they are all without fault is also incorrect. All designs have compromises, weaknesses, and strengths. This particular design has a lot relying on the end users getting the interface correct, which is an issue.

My aim here is to provide education with which other users can draw their own conclusions. We each have to judge the risk that we subject ourselves, and those that rely on us to. In my opinion, this tower design is acceptable. In my experience frequent checks for damage, and careful use (procedural safety, not inherent safety) is keeping my risk low.

Considering those bolts have now been reported to pull/wiggle out in at least a dozen cases, what are the options?
How does one know that thread is getting out of wack?

Visual inspection of threads, feel of the running torque during insertion/threading.

The OEM bolts can be replaced but can't buy the base (with female thread), it is one part with the tower...

The base would have to be replaced by a machine shop should those threads be damaged. I intend to remove my tower this winter to run some wires. There is a snap ring that will remove the base from the tower I think. I'll be certain to document that process. The fact that Yamaha doesn't sell that piece as a repalcement part is a mystery to me, as the premise of damaging those threads had to have crossed someones mind at some point.

Not trying to be argumentative, but I think this is a serious problem, it's probably good letting others know and beware.
(I wish I had known about this issue!)

I understand. You have also had a VERY severe interaction with this particular issue. I think you've done an exceptional job of not lashing out publicly at Yamaha over it. My over arching goal here is to provide some insight for others to read/understand on the issue at hand. Provide some information, and possibly some insight so that others are aware of the root problem, causes, and preventative measures.

As AR owners, we're all in this together. Education is key in sound decision making. I don't want to see any more harm come from this design issue. I also don't want to scare away existing or potential new owners by making a problem worse than it is. New owners should inspect these bolts before delivery, and existing owners should check them on a regular basis both for damage and tightness

 

[swatski]

100% Serious. No sarcasm, shenanigans, or ballywho intended


There is an obvious difference in feel to a cross threaded bolt as compared to a normally threaded bolt. Running torque could be measured as well. The hand knob should not be used to "pull down" the tower, but only to tighten against the tower once in the fully "up" position. There are enough threads engaged in my experience (limited to two boats) that you can tell if it is a "free running" thread, or if the thread is damaged. Measuring running torque, visual inspection for damage, and "feel" are the only way to measure this.


Correct, and this is a problem


IMO if the threads are free running until tight against the tower, then a proper torque should be specified. I use "damn hand tight" for my torque setting, however including a hex head and tool from the factory would go a long way in clarifying how these are supposed to operate and be safe. A well torqued and loaded bolt will inherent not "wiggle out" under use. Damaged threads, under torquing, or improper seating will all aid in that bolt backing out, as you've experienced first hand.



You are exactly correct. Currently I am the only operator of my tower at this point. The dealer I use has high bay doors and doesn't have to lower the tower when it's there. I was fortunate in that it was not damaged before I received the unit, and has not been damaged since. I think others (including yourself) have not had this good fortune.




My point in the post was not to say its a good design or bad, merely that in an as designed state it doesn't have structural deficiencies. To say that all AR forward swept towers are faulty is incorrect. To say they are all without fault is also incorrect. All designs have compromises, weaknesses, and strengths. This particular design has a lot relying on the end users getting the interface correct, which is an issue.

My aim here is to provide education with which other users can draw their own conclusions. We each have to judge the risk that we subject ourselves, and those that rely on us to. In my opinion, this tower design is acceptable. In my experience frequent checks for damage, and careful use (procedural safety, not inherent safety) is keeping my risk low.


Visual inspection of threads, feel of the running torque during insertion/threading.


The base would have to be replaced by a machine shop should those threads be damaged. I intend to remove my tower this winter to run some wires. There is a snap ring that will remove the base from the tower I think. I'll be certain to document that process. The fact that Yamaha doesn't sell that piece as a repalcement part is a mystery to me, as the premise of damaging those threads had to have crossed someones mind at some point.


I understand. You have also had a VERY severe interaction with this particular issue. I think you've done an exceptional job of not lashing out publicly at Yamaha over it. My over arching goal here is to provide some insight for others to read/understand on the issue at hand. Provide some information, and possibly some insight so that others are aware of the root problem, causes, and preventative measures.

As AR owners, we're all in this together. Education is key in sound decision making. I don't want to see any more harm come from this design issue. I also don't want to scare away existing or potential new owners by making a problem worse than it is. New owners should inspect these bolts before delivery, and existing owners should check them on a regular basis both for damage and tightness

Man, great post! Very informative.
Something every new AR owner should read!

--