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29er lower mast joint


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Hi there,

I'd like to see if someone has had some similar experiences or even even a good solution for a problem I have with my 29er mast. Even under a moderate forestay tension and no dramatic crashes or dragging the mast tip along the seafloor the middle part of the mast gets pushed into the lower part. The movement seems to be limited only by the two parts of the sail track jamming against each other which can't be good for the rivets holding them.

It's not the first time I have to address this problem. In the original design the four M6 bolts that hold the spreaders to the mast do secure the two mast parts together as well. They are screwed into an aluminium insert inside that doesn't provide a way to properly torque the bolts imho. (Sorry for the large pics.) Of course in the long run, the holes in the two mast parts either get worn out or corrode and the loads on the mast do the rest.

DSC_1351s.jpg.907d7cd8c041c7b6b5336d33b71f2d8d.jpgDSC_1353s.jpg.8441a4173a9f56e6ac0636631a18ebcd.jpg

I thought that real nuts would be a good idea and did a stainless steel insert with welded-on nuts. (Cap nuts because I don't want my halyards to chafe on the bolt's ends. And yes, there is paint on the final part because electrolytic corrosion, bla, bla. )

DSC_1379cr.jpg.8393254b11e2834c36c5de39e02f020b.jpgDSC_1380cr.jpg.efe45e52d57a169d40f032d5076ddd37.jpg

Yes, I have torqued the bolts to their max. admissible torque, can't remember the number.

But yet, no luck, the friction between the two marts parts that is created by the four bolt's pressure is not enough to keep the mast parts from sliding into each other until this is stopped by the mast tracks jamming together. JB has been talking about this around 2017 on his website as well as in a proposal that can be found on the 29er class website, but I can't find any follow-up whatsoever on the topic.

http://bethwaite360.com/forthcoming-changes-to-the-29er/

https://www.29er.org/images/stories/2017/Cannoning-mast-resolution-17-01.pdf

Personally, I am not convinced that by adding two bolts into the same weak sleeve the problem can be solved permanently and I think that it's only a matter of time until those two holes get worn out as well.

 

Any ideas ? Did someone actually apply the six-bolt-solution ?

 

Cheers

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I have never seen a 29er, I'm trying to understand the reason why the two sections move into each other. 

The top section has an angled cut which mates to the angled cut on the lower section, so the top mast can only move downward if is can also moved aft at the same time. 

Is this correct? 

The original sleeve was a snug fit in the upper section, so to make it move aft the diameter of the sleeve must be reducing.

The only way this can be happening is wear due to movement between the two parts?

I have read the attached docs a couple of times. B suggests using rivets instead of bolts to make the joint tight. 

I assume the if you glued it all together and pop rivetted it then the movement would stop, the wear would stop and the the two sections would no longer "cannon"

Is this good reasoning? What have I missed?

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8 hours ago, Dart96 said:

I have never seen a 29er, I'm trying to understand the reason why the two sections move into each other. 

The top section has an angled cut which mates to the angled cut on the lower section, so the top mast can only move downward if is can also moved aft at the same time. 

Is this correct? 

The original sleeve was a snug fit in the upper section, so to make it move aft the diameter of the sleeve must be reducing.

The only way this can be happening is wear due to movement between the two parts?

I have read the attached docs a couple of times. B suggests using rivets instead of bolts to make the joint tight. 

I assume the if you glued it all together and pop rivetted it then the movement would stop, the wear would stop and the the two sections would no longer "cannon"

Is this good reasoning? What have I missed?

The mid mast section slides inside the lower mast section, if there were no bolts locking the 2 sections together then all that would stop the the mid section disappearing into the lower section is the fact that the sail tracks from the 2 sections will be butting up against each other. I wonder if 2 full length slightly bent bolts might work, so the bolt goes from one side of the spreader bracket to the other side and the 2 nuts are then on the outside of one side of the spreader bracket. You would need to make sure there is no thread on most of the shank so the halyards don’t wear.  7111 is your spinnaker halyard external?

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Ok, I see my mistake. I'd assumed that as there is an angled lower edge to the upper section the there was a matching angled cut on the lower section. The two parts mating with an internal sleeve inside the lower section. The RS Feva has this system. 

So on the 29er the only thing stopping the masts sliding into each other is a few bolts!

Oh dear,  Oooops!! I can see the problem.

How one design is this boat? Laser restriction style?

If not I would make or find an internal sleeve identical to the lower section. Maybe 6" long. Push it up the upper section so that it would rest on the top of the lower section when assembled  and rivet it in place. This would give a permanent step inside the upper mast and distribute the load.

6" probably would not change the bend of the mast much. B says 4 rivets....

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The problem is, as always the evolution of the sailors.

When the masts was designed, which was 1996, no-one expected it would end up as a youth class and be at the level that it is, so where you have the SS plate, we inserted a 3 mm crescent of hi-end alloy, and if it was done with some panache, then you could tighten the M6, better if you used BSW 1/4" bolts tightly and effectively.

1/4" BSW have far courser threads and are far better suited to Alloy work.

What has happen in the ensuing years is the class has steady-fastly block any changes, for what I am sure are all good and sufficient reasons, but the shrouds started tearing down through the alloy due to increase rig tension and also due to increase down-haul tension (which is also transferred through that point) that are now all the rage!

A lot of work was done on the 6 bolt, and key-plate solution, so both the Trapeze wire and the shroud down force can be taken via key-plate and they have the potential to transfer the load more effectively.

The real solution is to transfer the loads via butt contacts, rather than slide contacts, but if your going to do that, your better off just going to a carbon solution which will 1/2ve the running cost in the long run, but the chances of that (or the butt solution) getting up anytime soon is unlikely.

Seriously suggest you look at the 6th MT, and make sure it's a CSK so you exploit the 45° rule, and see if you can find some BSW 1/4", also know as 1/4" 20  (20 threads / inch).    If done well, it will eliminate the issue for a longish time.

BTW, the SS place is not kosher, if it's found you will more than likely have to replace it (at best).   Get yourself some hi-end 6061 or 6063 alloy, a bit of 60mm OD tube works well.

Turner (Ovington) should be able to get some.

                                 jB

 

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1 hour ago, Major Tom said:

The mid mast section slides inside the lower mast section, if there were no bolts locking the 2 sections together then all that would stop the the mid section disappearing into the lower section is the fact that the sail tracks from the 2 sections will be butting up against each other. I wonder if 2 full length slightly bent bolts might work, so the bolt goes from one side of the spreader bracket to the other side and the 2 nuts are then on the outside of one side of the spreader bracket. You would need to make sure there is no thread on most of the shank so the halyards don’t wear.  7111 is your spinnaker halyard external?

Thanks for your input guys !

Internal halyard, works nicely.

If there was a bolt, as you suggest, going through the mast in other places, it'd be a new hole that isn't worn, at least for now. The load on the mast would be a shear load directly on the bolt, rather than relying on friction created by the bolts pulling the surfaces of the mast parts together. That would certainly be better, but I don't really want to add holes.

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31 minutes ago, Dart96 said:

So on the 29er the only thing stopping the masts sliding into each other is a few bolts!

Oh dear,  Oooops!! I can see the problem.

How one design is this boat? Laser restriction style?

If not I would make or find an internal sleeve identical to the lower section. Maybe 6" long. Push it up the upper section so that it would rest on the top of the lower section when assembled  and rivet it in place. This would give a permanent step inside the upper mast and distribute the load.

Well, that's the plan, but actually it's a little bit the mast tracks as well. I could of course shorten the sail tracks a few mms and the loads would again be only on the four bolts. Your internal sleeve suggestion is a good one from a technical standpoint me thinks, but most certainly not legal under the class rules as it might change the characteristics of the mast.

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35 minutes ago, JulianB said:

The problem is, as always the evolution of the sailors.

When the masts was designed, which was 1996, no-one expected it would end up as a youth class and be at the level that it is, so where you have the SS plate, we inserted a 3 mm crescent of hi-end alloy, and if it was done with some panache, then you could tighten the M6, better if you used BSW 1/4" bolts tightly and effectively.

1/4" BSW have far courser threads and are far better suited to Alloy work.

What has happen in the ensuing years is the class has steady-fastly block any changes, for what I am sure are all good and sufficient reasons, but the shrouds started tearing down through the alloy due to increase rig tension and also due to increase down-haul tension (which is also transferred through that point) that are now all the rage!

A lot of work was done on the 6 bolt, and key-plate solution, so both the Trapeze wire and the shroud down force can be taken via key-plate and they have the potential to transfer the load more effectively.

The real solution is to transfer the loads via butt contacts, rather than slide contacts, but if your going to do that, your better off just going to a carbon solution which will 1/2ve the running cost in the long run, but the chances of that (or the butt solution) getting up anytime soon is unlikely.

Seriously suggest you look at the 6th MT, and make sure it's a CSK so you exploit the 45° rule, and see if you can find some BSW 1/4", also know as 1/4" 20  (20 threads / inch).    If done well, it will eliminate the issue for a longish time.

BTW, the SS place is not kosher, if it's found you will more than likely have to replace it (at best).   Get yourself some hi-end 6061 or 6063 alloy, a bit of 60mm OD tube works well.

Turner (Ovington) should be able to get some.

                                 jB

 

It's actually reassuring that the 29er wasn't intentended as a youth class as it has become 100% in my neck of the woods.

I really appreciate your insights into the thread issue, I am pretty sure that my mast already had M6 bolts with their finer thread when we got the boat.

Since I haven't been able to find any follow up on your 6 bolt proposal, I wasn't sure it's a legal solution/mod and have tried to find a solution that doesn't involve drilling more holes. So it actually is ?

I'll go for the BSW / alu sleeve as soon as I can get my hands on that stuff ! (I suppose it's better to use a tap to create the threads in the sleeve rather than forcing the bolts through ? Just asking to be really sure...)

Cheers

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Checked out the 2019 class rules:

C.9 RIG
The following is permitted without the approval of the ICA Technical 
Committee. Unless stated otherwise items mentioned in this section may be 
obtained from any manufacturer or supplier.
Localised repairs to damaged equipment may be undertaken. Any repair shall 
not be used to reinforce an existing part or add a function.
C.9.1 MODIFICATIONS, MAINTENANCE AND REPAIR
(a) Replacement of fittings may be made and if needed to facilitate repair the 
fitting may be modified to accommodate slightly larger fixings.

I can see why JB proposes a rule change, current rules make rectification or mitigation difficult.

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Yes, always tap holes for bolts and use lube. Parafin works ok for aluminium. Do it slowly. Half turn forwards, quarter back to break up the dwarf.

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5 hours ago, Dart96 said:

Localised repairs to damaged equipment may be undertaken. Any repair shall 
not be used to reinforce an existing part or add a function.

I did fiber repairs to the two ends of the spi pole when I got the boat (had been badly split by a corroded aluminium insert) and was very careful not to change the pole's stiffness exctly because of this part of the rules...

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11 hours ago, JulianB said:

Seriously suggest you look at the 6th MT, and make sure it's a CSK so you exploit the 45° rule, and see if you can find some BSW 1/4", also know as 1/4" 20  (20 threads / inch).    If done well, it will eliminate the issue for a longish time.

I am sorry if I have to get back to you yet another time: I am wondering how far into the mast I should coutersink the heads ? I am inclined to think that it would be best to sink them all through the thickness of the mast parts:

 Image-11.jpg.e1fca27738df621f6772fdf5e3dbfedc.jpg

 

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7111, ask away, don't be shy, I'm actually quite a nice guy.

Yes, to get the benefit of a CSK it need be sunk so the head is flush.   Given that the issue with the mid joint is the outer 70 x 1.72mm tube, and the CSK part of a M6 is 3mm deep that mean it will go part way into the mid mast, (66 x 1.7) and that's a good thing, so leave it just a uM proud so say 0.1mm .

When you sink a CSK you get a huge increase in Surface Area [SA].

I just cheated and did it in CAD, but the last 1.5mm of the conical outer part (semi circle, so 1/2) of a M6 CSK MT has 34 mm² SA

That same bolt but measured on the shank it's 14mm² SA so even if you factor down the 34mm² x 45° (sin 45 = 0.71) you still 24mm² so quite a large increase.

The 2 x M^ CSK MT could quite possible do the same amount of work as all 4 M6 threads, and if you happen to find 1/4" BSW which is 6.4mmOD then they definitely will do as much as the existing 4 x M6 threads.

Re legality, I have asked Barry who is still the CIM of the 29er (Chief measurer) so as soon as he come back (he lives in Perth Australia) I will let you know.

I do believe Mackay are planning to use the new system straight away.    If I start making masts again, which I can't see avoiding, then I will also.

                     jB

 

 

  

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Barry is pretty sure it went through and that was a few years back, but for the paper work you need to go to Steph Banham <office@29er.org>

Who is the Exc Sec.

              jB

 

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20 hours ago, JulianB said:

I just cheated and did it in CAD, but the last 1.5mm of the conical outer part (semi circle, so 1/2) of a M6 CSK MT has 34 mm² SA

That same bolt but measured on the shank it's 14mm² SA so even if you factor down the 34mm² x 45° (sin 45 = 0.71) you still 24mm² so quite a large increase.

Thank you for the calculations, the results a pretty clear !

I already have my hands on a 1/4" BSW tap. Finding the csk stainless BSW bolts w/allen or torx head (vs Phillips or PZ) might take some time, but they'll show up eventually.

Any reason to csk the heads of the existing 4 bolts ? I dont think so because they won't go much farther down than the thickness of the spreader's material and this can't be of much use, right ?

I'll report back what the 29er office says on the topic.

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No point in CSK-ing into the spreader bracket as it's the 70mm tube that want to resist sliding not the spreader band!.

Just for fun I analysed it again

image.png.01b2f96da7d095c6e10112890ecd08f6.png

The red area is 1.7mm deep and comes in at 41.5mm²

The blue area is also 1.7mm deep and its 23.85mm²

Sin 45° = .707

Sin 30° = 0.5

I will let you do the maths, but your 2 x M6 CSK MT will do more than the 4 x M6 threads! 

 

 

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5 hours ago, JulianB said:

The red area is 1.7mm deep and comes in at 41.5mm²

The blue area is also 1.7mm deep and its 23.85mm²

Sin 45° = .707

Sin 30° = 0.5

I will let you do the maths, but your 2 x M6 CSK MT will do more than the 4 x M6 threads! 

Despite not being an engineer, I'll try to add my 2cts while I try to learn a little.

As far I as was able to recalculate, the red and blue areas are each half the surface around the corresponding 1.7mm parts of the bolt. The sin rule applies, because the surfaces are inclined with regard to the direction of the shear load. For BSW bolts it's sin 27,5° = 0.46 on the thread. The 'effective' surface of red vs blue is thus: 29.3 vs 11.9mm^2 which is more than the double.

But shouldn't one rather compare the surface of the conical part of the csk head *below* the red one with the blue one on the thread ? The one that'll sit in the mid-mast's wall and, being the smaller part of the conus, compares less favourably ?

That would be around 29mm^2 x 0.7 = 20.3mm^2 which is still not too far from the double of 11.9.

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I am not a engineer either.

Bottom line, the CSK solution doubles the capacity of the bolt to resist the "cannoning" (sliding) of the two tubes.

Whether the 66 x 1.7 or the double-er which is a segment of 60 x 3  does the lion's share of the internal load, I have no idea.

The original 49er mast had the same issue, 4 x 1/4" Monel rivets stopped it completely, (but it was illegal) they still went through about 4 masts for every boats sold.   (29er goes through about 2.5 masts / hull and has done so for the last 25 years)     Of-course the 49er went Carbon and that mast/hull ratio dropped to under 1.1, last count it was about 1.08.   

2 really scary things that come out of that.    #1 If you do the economics it has saved the 49er sailors, the 49er community about $3m/y for the last 7 years in buying masts alone, nothing to do with the hassle your now going through (time), the sails that have lasted longer, any of that.   

The 2nd scary fact is that the Laser is possibly higher (mast to hull count) than what the 49er was (in 2008).

The big plus side for the 49er is sales of hulls almost 50% (from a a sensible level, 2014, if I took the average of 2008-2013 then sales are up 250%) and yes sales of masts are up a similar amount, but the really big plus is if you now put the sales of SAILs over the number of hulls sold then that ratio has gone from 1.26 (2014) to about 3.3 (2019), and this increase in the SAILs to hull ratio is almost a straight line.    So not only are more 49er's being sold, but people are using them almost 3 time as much/often and it almost exactly correlates to the settling down of the Carbon Mast transition.

My point being the pain and the hassle you are going through now is not un-common, and we can make it go away and history tells us, the class would be in a much better place.

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I'm seriously scribbling notes for the kids down at Hunters Hill Sailing Club on all of this ... we now have 18 29ers and an FX in training and these sorts of issues and discussions are gold!! Thanks all!!

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On 5/27/2020 at 3:11 AM, JulianB said:

The original 49er mast had the same issue, 4 x 1/4" Monel rivets stopped it completely, (but it was illegal) they still went through about 4 masts for every boats sold.   (29er goes through about 2.5 masts / hull and has done so for the last 25 years)     Of-course the 49er went Carbon and that mast/hull ratio dropped to under 1.1, last count it was about 1.08.

Probably the dynamics in the 29er class are a bit different than in the 49er because it is mainly sailed by kids who don't spend too many years in the boat. Thus the long-term investment for the carbon mast doesn't hold as much attraction for them ?

I have explained the whole issue to Barry Johnson. Hope it's ok with the rules...

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1000% understand, very hard to get a parent to look beyond their child's involvement, even if it's costing them a bomb, they can't see beyond the nose on their face.

And there is absolutely no reason for them to want to do that.

Dose not mean it's not very unfortunate and by definition, short sighted.

Barry's a great guy, he and Steph will put you on the right path!

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I can absolutely guarantee that every parent of our 9er squad would go with the robust and cost effective carbon mast if offered.... they have all seen how well the laser top section performs, how the Flying 11 rig performs, and are surprised that a modern craft like a 29er doesn't have a carbon rig!!

 

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OK, firstly I'M NOT DOING THIS - PERIOD. I have done my bit, spent my money/time and I have happily moved on!

2ndly, this has all been canvased before.   &

3rdly the perfect opportunity has gone that being a large institution funding the start-up, so what is needed now is 10-15 parents having to put 25% down 3 months out and that aint going to happen.

As for cost, mainsail is about 5-7% more because its 5-7% bigger, it's about that simple.     (Jib and spinnaker are the same sails, so there is no change it that) but if you go carbon mast, you have to go square head (to get the benefit), and you have to up the area, because the inertia is reduce so if you don't you will end up with lighter and lighter crews.    Against that the mainsail will last upwards of double the life span of the existing sail for 2 reasons.    #1 is the the mast bends 1/2 what a Alloy mast bends and therefore the sail is subjected approx 1/2 the stresses, & #2, the main is designed to incorporate all the design tweaks that have been developed in the 49er, to overcome the modern way of sailing skiff, most notably excessive down-haul tension.

The cost of the mast is approx 10% more, (last costing which was 18 months ago), and that's because 3 fiber wound tubes cost more than 1 fiber wound tube plus 2 extruded alloy tubes, but gain, against that, cost of rigging a Carbon mast is 1/2 that of a alloy most (there are no sleeves, you glue the track & fittings on (not rivet it) etc etc) and you can incorporate things like the new boom and vang system, both do the same job, and can be retro fitted, it's just they are extruded/milled/anodised all in the same factory.    

An example, the new 49er carbon mast spreader (Carbon arms, alloy Sprocket) that we are developing now, which could be easily modified to become a 29erC rig spreader is likely to cost $USD220-250.   The existing 49er carbon spreader is around $USD500.   Virtually no weight difference and the new spreader, should be infinitely more robust, far more simple, far less things to go wrong and is repairable, so if you do slam it on the concrete, you can glue a new arm on.

The current 29er spreader is £255 (inc VAT) so its about $USD255 (exc VAT) so about the same for a smaller welded alloy spreader.

And to be blunt, if technology (mostly the bicycle revolution) had not delivered such benefits then you would be worried. 

The big advantage is that Carbon mast can quite literally out live the life of the boat.     Possibly the biggest advantage of the Carbon Mast is exactly what has happened to the 49er/FX is that not just sales of boats have gone up and the use-age of those boats is up 3 fold.   One could (wildly) deduce that the boat becomes a lot more enjoyable to sail!  

All this has come back and smacked me in the eye, because the guy who owns the iP for the 29er Topmast (and spin poles for both the 29er and 49er) died suddenly just before Christmas. So I have taken over the audit process for the widow (Anne).   And this number, Mast/hulls ratio, drops out the bottom of the page right alongside the number of boats sold.

In last month audit that ratio was 2.2.   

Also as part of me taking the audit burden off Anne, is I am gaining access to the last 10 years, so I can verify the long-term ratio. (the late Adrian did a amazing job)

But, and it's a calculated but, the ratio is 2.2 and if it can be dropped to 1.1 (49er rate) then that equals a 1.1 x 100 x $2,200 (cost of a 29er mast) = approx $1/4m/year saving to the 29er community!

As Malcolm Page commented few days back, its sensational that I have the facts.   (this was 49er/FX related, Malcolm being a 2 x GM in the 470)

As Stanno has said, it's happened in the 49er/FX, also F11, its happened in the I14, 5o5 and the Laser is proving beyond doubt the correlation.

And even just going 1/2 way and adoption the new boom, Vang system and Rudder stock would save the 29er community.

Unlocking Asia, would save the existing 29er community a large % of $USD80k per year in the cost of funding the YW's.

Inaction costs big-time!     Controlled evolution is preferable to inevitable revolution.      And this is true of all classes, not just the 29er!

The other rider, because it so blatantly obvious is that builders don't do this to make a quick buck, in the case of the 49er, it cost them $2m/y in lost sales of masts, in the case of the 29er it would cost them $1/4/y in lost sales of masts.

That being said, and this is happening right now WRT the new 49er/FX mast, come in early and come in numbers and the cost of the mast and sail can be defrayed. 

So the builder are looking long term, they are going to be part of a more vibrate and enthusiastic sailing community!

              jB

 

 

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Thank you for the detailed numbers !

If I did the math correctly the mast/mainsail combo plus s&h must be in the range of £3000, based on the current prices on the Ovington website. That's quite an amount of money when compared to the value of a decent used boat. On the other hand, if someone has to replace a mainsail and/or the mast the extra cost is pretty small.

For the top sailors this shouldn't be much of an issue if they are to buy new hardware sooner or later anyway. The mid level people would probably be not very enthusiastic about it. Anyway, since it's a one-time transition for the whole class it'd be the sooner the better I think because later means there will be more boats to be retrofitted as they are being built. (And if you happen to have an almost worn out mainsail the addition cost will only be the mast.)

So, if I understand correctly what you are saying, production could start if there was an initial order for a batch of at least 10-15 masts and sails ?

 

I just got the go-ahead for the mast joint repair/mod from Barry. He asked me to document what I am doing for the class which I'll gladly do of course.

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If 10 people went to say Ovington, or Nautivela or Mackay and said they wanted the 29erC rigs, then just like Ovington recently put a 29erXS rig on a WS/ICA plagued 29er hull, they could sell the hull with a 29erC rig, or they can sell 29erC rigs on their own to retrofit existing 29er hulls (and the same foils and boom and pole and jib and spin).

As has been stated many times, once the boat leaves the builders premises, what the client dose with that boat is her/his business.

How anyone, anywhere believes they can control what happens to a boat once it's left the yard, is laughable.     The FX is a classic case in example, how dose any one think I can control a young lady desiring to sail a FX, getting a fully plagued 49er hull and then buying a FX rig and sailing it all the way to Olympic level with WS endorsement!

You keep on talking about the top 10, you should think the other way.

Pretty obviously within 2-3 years of owning a 29er, just like any other class, your going to have to buy new sails or a (mid-) mast say.    

If you put a 2-3 year transition on the change, then you say, in 3 years time the 29erC rig can sail in Gold fleet and win the worlds.

In 2 years time the 29erC rig can sail in Silver fleet.

Obviously 3 year out you let anyone who doesn't expect to make Silver or Gold use either rig.   If they are new to the class and have brought a new boat, then they could buy the hull and go get a 29erC rig and sail with the same rig for 3 years.

The numbers tell us, that, you wont have to do the repair your doing now, and the kids will want to go sailing more often, because its more fun.  (3 fold increase in 49er useage post the switch to the carbon rig) 

The parents who have already invested in the alloy rig can continue to use that, sure they will end up buying this and that to keep everything up to speed but that's their prerogative.

When they go to sell the boat, they will have a great training rig with the boat, but the reality is, that what a 3 year old rig is anyway.

In Auckland, the 49er voted on and approved a "red tag" policy, to do exactly this WRT to the introduction of the new Mast and Spars.     WS ended up turning it down, because the Olympics where (at that stage) too close in their opinion.    Now, due to inability to get SS masts, it's going to happen whether WS like it or not, what we call a hot launch, and everything will be black tagged from the get go, but you just can't use it in the Olympics or to get to the Olympics.    Same-same, only different.

Need to stop thinking rock-stars and think Weekend Warriors, it's the WW that will get the most benefit from evolution.     RS's won't want it!    The kids probably want it, but the parents hate change, hence 90% of the worlds parents wanting their kids to sail what they sailed.

Like that's going to happen, and we wonder why there is such a drop off in sailing.

                                   jB

 

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1 hour ago, JulianB said:

The FX is a classic case in example, how dose any one think I can control a young lady desiring to sail a FX, getting a fully plagued 49er hull and then buying a FX rig and sailing it all the way to Olympic level with WS endorsement!

What’s wrong with that? Are FX hulls differentiated with a different plaque?

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Absolutely nothing is wrong with it, my point is, if for whatever reason I may have objected to it, which I hasten to add that I don't, then there is also absolutely nothing I can do about it.

Those people who try are fighting a very short term battle and will simply be overwhelmed tomorrow.

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Just BTW

image.png.724ad5857d1e37c88fbcd9cb9f0ecc5e.png

29erXS rig, in Lake Garda

image.png.24a26679f585ad06aa86818e113ee881.png

Don't actually know what this is as can't read Italian, but its Sydney harbour

Came from Italian 29er forums.

image.png.9a7360e566477f17f57153c5e8bab69a.png

And 29erXX/carbon masted 29ers sailing in the USA.

Probably all Ovington WS/ICA plagued hulls.

And you just can't stop people doing it!

To try is futile!

 

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BTW, are any of the rigs (carbon mast + square top main) that were used for testing still lying around somewhere? I am not talking about the XX rigs, but rather the "std" 29er rigs.

Wouldn't mind playing around with one (just for fun, not racing)

 

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Last time I saw the 29erC test rig, so this is the mast that is 5 years old and has sailed in 7-8 countries was 8 months ago on the rack in Arco, Lake Garda.      I think the mainsail is with Paolo at Nautivela, in Milan.

 

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9 minutes ago, JulianB said:

Last time I saw the 29erC test rig, so this is the mast that is 5 years old and has sailed in 7-8 countries was 8 months ago on the rack in Arco, Lake Garda.      I think the mainsail is with Paolo at Nautivela, in Milan.

 

Are there many 29XX rigs laying around in Australia?

Living well away from the big cities, I get the impression the 29XX's aren't much of a thing here any more, but I could well see that one would be useful for my training group.

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There where about 300 29erXX rigs sold.   You could probably find a one in the UK, as we sold our last one in Australia about 4 years ago.

They also fitted 59ers, so there was a double market here.    So all our stock bare a few sails sold, and there is a person not to dis-similar to your self opperating out of WSC that loved the 59er so he ended up with most of the excess parts.     Don't know where he is these days. 

29erXS still sell, but I think that most people jump to the FX now, so the 29erXX has lost it's place.

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Thanks Julian

Just looking for possible boats to cheaply expand the 'lending fleet' of twin wire boats that I use for my trainees.

I must admit, putting a trapeze or two on some old 59ers has occurred to me also, given most of my sailors are in the 50 to 60 kg range.

But the problem with any cheap option is that many of the women are highly competitive by nature and enjoy being able to go to a proper national title, or even just club sailing with a reputable VYC.

Modifying other classes with more trapezes might help with club sailing, but definitely produces a second best alternative..

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  • 2 weeks later...

Update on the mast issue:

As far as the material for the sleeve goes, Ovington is finally able to provide me with a piece of mast tube, should be here in a week. (Shame I couldn't find a wrecked Laser lower mast as it should have the correct dimensions.) I like the idea of using coarse threaded bolts, but BSW is really hard to come by nowadays, so I have opted for 1/4"-20 UNC stuff.

Since I have to make six new holes/threads in the new sleeve I might as well enlarge the existing holes in the spreader and mast parts a little and use UNC bolts everywhere, csk in the additional two holes and non-csk heads in the existing holes. Aligning the new sleeve's smaller holes for the threads in the center of the existing holes in the mast parts will be an interesting exercise :)

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1/4" 20 UNC thread is very close to a 1/4" BSW.

But don't over look the Heli-coil or Re-coil option.

image.png.d717be518b54b16368b3567f6246aac0.png

This is the thread, that you insert, its made of SS, and if you expoxy or Plexus it in, even good Spar-bond, the electrolysis will be miniumal.   ID thread is M6, OD thread is a mungrel but approx 7.4mm OD so the surface area is up 170% approx.   (you can see the knick in the tail, that's where you break it off after you have inserted it.

image.png.f2fbc569927541b09cca83c9427730c5.png

This is the kit, they normally inc, 20 of the "thread's" (spring thingies), a drill, at tap, a inserter and a break off tool.   We can buy them here for about $AUD45 for the kit.   (€30)

With the 29er you will have a 3mm sleeve secured to the inside of the 1.74 (x 66mm-OD) mid mast, so you end up with 4.7mm of material and the heil-coils will act a little like a rivet in holding the 2 together as one (so there are double bonuses in using them.)

You may have to cut it down in length, simple side cutter do that. as you want it to be solid in the Alloy and not extend beyond.     Put 6 of these in well and it "aint going anywhere!!"

 And if you loos a 1/4" 20 MT in Garda in Septemebr,  it's a major, where as you will be able to pick up a M6 MT anywhere (from that Laser dealer in Arco.)

Just don't get hung up on 1/4" BSW, it will take you less than 5mins per Heil (Re) coil to put them in place, and its a ligitimate repair.

                              jB

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  • 6 months later...

Hello guys,

me thinks  it's about time I report back on what's happened to my mast joint fiddling since the last six months. I hope I can piece the details together from memory...

 

Stuff:

Ovington sent me a nice piece of mast tubing with a 3mm wall thickness which is already a good thing because the old one was only 2mm, I swear. I cut it in half, so now I have a spare as well.

I got UNC 1/4-20 SS bolts, raised head for the four spreader holes and csk heads for the two new holes plus a tap for the thread. I would have liked to find bolts with torx heads but could only get hold of allen heads.

 

Work:

First, I had to make a piece of wood that would hold the sleeve in place inside of the mast while drilling etc. This has to be large enough to lock the sleeve in place once it's jammed in there, but not too much or the two mast sections won't fit together.

As planned, the hard part was drilling the holes in the new sleeve dead in the middle of the existing holes. Of course they have to be smaller than the existing 6mm holes because there has to be some material around the holes in the sleeve left to cut the new 1/4" thread into. So I used a 3mm drill with a small piece of tube (ID 3.0, OD 6.0) around it to guide the small drill in the center of the hole. The 3.0mm were enlarged to 5.0mm afterwards and then the threads cut into the sleeve. The holes in the spreader attachment and middle/lower mast parts had to be enlarged to 1/4" as well of course.

The two new holes for the csk bolts can easily be drilled just 20mm above the spreader bar sleeve, starting from 3.0mm, then enlarging, threading, countersinking as per my drawing above etc. Because the heads are quite big they are not completely flush with the surface, but that's only an optical problem.

I even took the time to look up the max torque for 1/4" steel bolts in aluminium because I have an old and nasty habit of destroying threads with too much of it... (must be around 10Nm)

All six bolt heads got a small (blue) mark on one side, so I can verify if they get lose or not.

IMG_20201219_164529cr.jpg.b631d0a033d77ae8df9f130b0acfe784.jpg

IMG_20201219_164547cr.jpg.79ba267478c45e156b7e93adcda2c593.jpg

Results:

Well, we have since taken the boat out on the water some 10 to 20 times in moderate winds and the assembled mast has spend quite a few hours on the road as well.

Sadly it seems that that the mast is still doing its cannoning because the 1mm gap between the middle and lower mast track ends has disappeared and the lowest bolt on the starboard side did loosen itself half a turn (see first pic), BUT the csk bolts are still very firmly in place and the tracks do not seem to truly jam one into the other. I probabaly forgot to put some Loctite on the threads.

 

If things evolve, I'll tell you here. I'm not sure this is a mod that can easily be applied by anyone with a cordless drill in a boat park...

Because our trip to the kiwis this winter fell through thanks to the bloody pandemic we had some money sitting around and because they sell them dead cheap now we got a brand new XX rig from Ovington. Can't wait to try that for the fun of it :)

Cheers

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For future reference, standard torque spec for a ferrous bolt into aluminum would be based on 10 threads of engagement depth (which is the standard minimum for full strength into aluminum). No idea what the carbon thread engagement standard is, but you may be near thread yield.

Generally on SA when I offer up something like that^ someone who knows a lot more than me about everything will provide some real data and maybe even call me a fuckwit. I don't mind being fuckwit-bait if we all learn something.

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Gee, the significance of the number of threads that are really bearing the load didn't cross my mind until now, thanks.

Well, 20tpi equals 1 thread per 1.27mm or less than 2.5 threads in the 3mm sleeve. To keep the same load on every thread as in your 10 threads, this would mean the torque has to be reduced by the same factor of 2.5/10 = 0.25 ? That's not much torque left... Ok, but since the (shear) load should be on the csk head now, rather than on the threads of the four other bolts, it's propably acceptable to torque them a little less.

BTW I still wonder why ffs the axial load bearing connection between the two lower parts of the mast is made on one side only (where the bolts are) as this will make the mast flex backwards as the load is applied.

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If you go back through SA you will find other references to exactly this same issue.

Everything evolves, in this case the kids are evolving, and yah can't stop that!

The 49er and latter the 29er mast came from the 18teen masts and they had exactly the same sort of cannoning/sliding neckdowns and in most cases where riveted together, I think 4 x 3/16" (M4.8) rivets plus glue was enough to hold them.

49er rapidly progressed to 4 x ¼” (M6.4) rivets prior to going carbon as the trend to use more and more downhaul washed across the sport, probably coming from Windsurfing.

49er then went Carbon and butt jointed and other than a bit of torque, problem gone.

29er issue is exacerbated because the excessive use of downhaul so they don’t have to use vang.

Here in Australia, “apparently” get the vang wrong, and you up, for at best a new mid mast, so people are sailing with excessive (250-300kgs) of downhaul.

Sails where never meant for that nor where the joints.

And I hasten to add, this is true across the whole sport, not just the 29er.

So to fix the problem your up for,

#1 change the fixing of the joints, and that is happening, with T-balls and extra CSK bolts.

#2 Change the alloy joints so as to rivet on a butt joint to take the load, it would mean altering the angle cut and still bolting on the spreader, and it won’t solve the “vanging” issue.    Or

#3 Go Carbon, just like the 49er did and ½ the maintenance costs.

Again I hasten to add, it’s the kids that are evolving, so it’s a problem that is manifesting itself across all classes and the whole sport itself, so if you don’t have the issue in your class now, you do, you just can’t see it!

The I29erCA has allowed #1 and that is evolving also.

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Ok, can't wait to see how it's done one the XX carbon mast.
Julian, it seems there isn't much literature on the XX. The only thing Ovington could dig up for me is the fitting guide for the gunwhale extensions. Is there a rigging guide or something ? Trial and error is fun, but life is short, so any help from you on that one would be great...

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There is buckets loads on it, most of it is with the I29erCA.

Jen Glass, (USA, Seattle) who was the pres of I29erCA was also pres of I29erXXCA, so between her and Jerelyn, there should be bucket loads.   When the XX "disolved" to allow a clear path for the FX, everything inc $$$ went to the I29erCA.

There a girl in Germany who seems switch on, Ovington would have her contact, I helped her recently, she put a XX rig on a boat in the last year.   Let me see if I can dig out her contact.   In Australia, there is more interest in the XS.    We are sort of covered in the XX range.

The XX rig is butt jointed, the XS rig is Cannon.

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Not sure how much of it is evolution.... I bought hull 200 in 2008 or 9, and it was sufferenint front pile-driven mast as well, even when I first bought it. Had to keep shaving the tracks down to keep them from butting off. Not sure what the numbers are today but I ran 21units on the forstay for heavy air, maybe 24 if it was survival conditions. Normal was 18. Or was 18 super light? Shit it's been a while. 

 

Also..... What's the xs?

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And the full solution is a butt joint and that has been in the winds for over 12 years.

Turning point for me was 2004 SFO worlds, but we where asked to delay modifications pending the 49er mods.

Some mods we simply had to do, (to the hull) and they have worked pretty well.   Consulting with Brazilian's right now re-birthing a "mature" 29er.

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13 hours ago, JulianB said:

There a girl in Germany who seems switch on, Ovington would have her contact, I helped her recently, she put a XX rig on a boat in the last year.   Let me see if I can dig out her contact.

That would be awfully nice, the name may already be enough... Any ideas ?

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OK, I found her, but let me do the right thing and contact her first, before spreading her email across the internet.

I don't even know how old she is, so that would be very inappropriate.   Better still, send me a PM and I will pass it on for you.

Ahhhh, Garda, I was having a bozzy Christmas lunch yesterday with some 18teen mates and Garda, Bandol and Geneva where all high in our memories. 

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