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Super Maramu Main Mast Furling foil Sheered

Graham Boyd
 

SM Main mast furler foil sheered at base just above the gear box (see pictures).

This metal fatigue event rather spoilt our Chinese NY cruise yesterday. The actual sheer occurred when furling the sail head to wind in 15 kts of wind. 

Has anyone else suffered this failure? If so what was the fix?

I understand from this site that the top of the foil in the mast is unsupported. This makes me wonder if there is sufficient "extra" length of foil in the mast to just drill new holes in the foil above the sheer line and drop it back into the gear box. Would the swivel then "fall off the top" of the foil when the sail is hoisted? Failing that extending the foil at the top to support the swivel with the sail up could be the answer.

Any thoughts/experiences welcome!

Graham
SM140 Sula
Hong Kong

jj

Danny and Yvonne SIMMS
 

Hi Graham,

I would say you are fine to drill a new hole and drop the foil. As to cause I will lay odds that the  bearings in rhe swivel at the top are full of salt making it hard to turn and that extra load directly contributed to that failure.

Regards

Danny

SM 299

Ocean Pearl

On 27 January 2020 at 15:28 "Graham Boyd via Groups.Io" <crwggb@...> wrote:

SM Main mast furler foil sheered at base just above the gear box (see pictures).

This metal fatigue event rather spoilt our Chinese NY cruise yesterday. The actual sheer occurred when furling the sail head to wind in 15 kts of wind. 

Has anyone else suffered this failure? If so what was the fix?

I understand from this site that the top of the foil in the mast is unsupported. This makes me wonder if there is sufficient "extra" length of foil in the mast to just drill new holes in the foil above the sheer line and drop it back into the gear box. Would the swivel then "fall off the top" of the foil when the sail is hoisted? Failing that extending the foil at the top to support the swivel with the sail up could be the answer.

Any thoughts/experiences welcome!

Graham
SM140 Sula
Hong Kong

jj

ngtnewington Newington
 

In my opinion you may be able to drop the whole thing down about 10 cm or whatever the depth of the gear, if necessary you could shorten the top lashing between the sail and the top bearing. But to strengthen the foil I would try and source an internal bushing that slides snugly up the foil. This would spread the load. There is quite a lot of torque onto that foil when furling the sail all concentrated at the bottom. To simply use the foil alone may not last very long.
What material should the bushing be? If it is perfectly round then the obvious choice is aluminium, machined to fit, but it could be some kind of composite material or even in a pinch, for an at sea fix  a piece of hardwood until a machine shop is found. 

Nick

Amelia AML 54-019

Kilada Greece

On 27 Jan 2020, at 08:24, Danny and Yvonne SIMMS <simms@...> wrote:

Hi Graham,

I would say you are fine to drill a new hole and drop the foil. As to cause I will lay odds that the  bearings in rhe swivel at the top are full of salt making it hard to turn and that extra load directly contributed to that failure.

Regards

Danny

SM 299

Ocean Pearl

On 27 January 2020 at 15:28 "Graham Boyd via Groups.Io" <crwggb@...> wrote: 

SM Main mast furler foil sheered at base just above the gear box (see pictures).

This metal fatigue event rather spoilt our Chinese NY cruise yesterday. The actual sheer occurred when furling the sail head to wind in 15 kts of wind. 

Has anyone else suffered this failure? If so what was the fix?

I understand from this site that the top of the foil in the mast is unsupported. This makes me wonder if there is sufficient "extra" length of foil in the mast to just drill new holes in the foil above the sheer line and drop it back into the gear box. Would the swivel then "fall off the top" of the foil when the sail is hoisted? Failing that extending the foil at the top to support the swivel with the sail up could be the answer.

Any thoughts/experiences welcome!

Graham
SM140 Sula
Hong Kong

jj

Beaute Olivier
 

Hello Graham,

originally, there is around 20 cm of foil left at the top, above the swivel, with the original lashings (top and tack).
This means that in the foil's life, cutting off the bottom for new bolting can be done three times.
You may not know if the previous owners have already cut the foil at the base (for the same cause you face now). So, with your mainsail installed, and 10cm lashing between the swivel and the sail's top, you should go up the mast and look how much length of foil there is left above the swivel's top.

The cause of the bolts sheering the foil at the bottom is only using the furler (a lot!). Of course, some foils will last longer than other ones just because of the kind of use. If you handle the mainsail furler gently, the foil may last longer.
Be kind with your furlers and don't overload them (when the sail is fully in the mast, don't squeeze it by over using the furler). Don't try to adjust the mainsail under load.

You should drop the mainsail once a year to check the swivel (is it turning free?) as a seized swivel will add more load to the bottom bolt junction (and the motor and gear-box!!).

For those who have a short foil (already cut off a few times) and who cannot cut it anymore unless the swivel comes off the foil, the next step is to have a shorter mainsail made(at the luff).

Good luck and be kind with your AMEL, she will give it back to you...

Olivier

 

The cause is very likely the jamming when furling or unfurling. Most often it is caused by the addition of vertical battens on a SM. 

I will send you a page from my book on the step-by-step procedure with photos. Look for it in about an hour. 

Best,

CW Bill Rouse
Amel Owners Yacht School - www.AmelOwnersYachtSchool.com
720 Winnie St
Galveston Island, TX 77550
+1(832) 380-4970


On Mon, Jan 27, 2020, 2:50 AM ngtnewington Newington via Groups.Io <ngtnewington=aol.com@groups.io> wrote:
In my opinion you may be able to drop the whole thing down about 10 cm or whatever the depth of the gear, if necessary you could shorten the top lashing between the sail and the top bearing. But to strengthen the foil I would try and source an internal bushing that slides snugly up the foil. This would spread the load. There is quite a lot of torque onto that foil when furling the sail all concentrated at the bottom. To simply use the foil alone may not last very long.
What material should the bushing be? If it is perfectly round then the obvious choice is aluminium, machined to fit, but it could be some kind of composite material or even in a pinch, for an at sea fix  a piece of hardwood until a machine shop is found. 

Nick

Amelia AML 54-019

Kilada Greece
On 27 Jan 2020, at 08:24, Danny and Yvonne SIMMS <simms@...> wrote:

Hi Graham,

I would say you are fine to drill a new hole and drop the foil. As to cause I will lay odds that the  bearings in rhe swivel at the top are full of salt making it hard to turn and that extra load directly contributed to that failure.

Regards

Danny

SM 299

Ocean Pearl

On 27 January 2020 at 15:28 "Graham Boyd via Groups.Io" <crwggb@...> wrote: 

SM Main mast furler foil sheered at base just above the gear box (see pictures).

This metal fatigue event rather spoilt our Chinese NY cruise yesterday. The actual sheer occurred when furling the sail head to wind in 15 kts of wind. 

Has anyone else suffered this failure? If so what was the fix?

I understand from this site that the top of the foil in the mast is unsupported. This makes me wonder if there is sufficient "extra" length of foil in the mast to just drill new holes in the foil above the sheer line and drop it back into the gear box. Would the swivel then "fall off the top" of the foil when the sail is hoisted? Failing that extending the foil at the top to support the swivel with the sail up could be the answer.

Any thoughts/experiences welcome!

Graham
SM140 Sula
Hong Kong

jj

Graham Boyd
 

Thanks everyone for the quick replies. I've owned Sula for 15 years now and pretty sure this repair wasn't done by the previous owner, so looks like it should be reasonably straight forward. Ten years ago we bought a new mainsail with small vertical battens from Deme Voils. Although through great care, we have had very few jams over these years, one does have to be quite disciplined in the manner one furls and unfurls compared to the non battened sail. Despite that we won't be going back to no battens at the next sail renewal.

Given her age and the huge amount of use our boat gets, a failure like this should probably have happened a lot earlier!

Graham 
SM140 Sula 
Hong Kong

Mike Longcor (SV Trilogy)
 

If there is noticeable play back and forth between the main foil and the bolt, is there anything one can do to slow down or minimize the metal-on-metal wear and tear? Perhaps a bushing or sleeve on the bolt would eliminate the gap, but there probably isn't enough space above and below the bolt as all the wear is horizontal.

Waiting until the foil shears itself would probably create some unneeded excitement at sea. Cutting/shortening the foil before it fails seems wasteful. Has anyone tried what Nick has suggested? An internal bushing slid up inside the foil to spread the loads and reduce fatigue seems like a good idea. Or perhaps with proper care the "three lives" provided by design is enough to cover one's lifetime if not the boat's lifetime. If that's the case, would it be advisable to cut my foil preemptively?

Graham, will you attempt any extra reinforcement when you do your repair?

Mike
SV Trilogy - SM23
Opua, NZ

James Alton
 

One thing that could affect the wear rate of the extrusion attachment hole is the bolt itself.  Check to be sure that there are no threads in contact with the surfaces that bear the torque stresses.  The smooth part of the bolt should in other words be  long enough to allow tightening when bottomed.  It may be necessary to have a custom bolt made to attain the correct length.  One can think of the threads of the bolt as a sort of a file that will chew out a bit of aluminum each time the joint is loaded.  

The internal bushing sounds like an interesting idea.  

James
SV Sueno
Maramu #220

On Jan 28, 2020, at 12:10 AM, Mike Longcor (SV Trilogy) <svtrilogy53@...> wrote:

If there is noticeable play back and forth between the main foil and the bolt, is there anything one can do to slow down or minimize the metal-on-metal wear and tear? Perhaps a bushing or sleeve on the bolt would eliminate the gap, but there probably isn't enough space above and below the bolt as all the wear is horizontal.

Waiting until the foil shears itself would probably create some unneeded excitement at sea. Cutting/shortening the foil before it fails seems wasteful. Has anyone tried what Nick has suggested? An internal bushing slid up inside the foil to spread the loads and reduce fatigue seems like a good idea. Or perhaps with proper care the "three lives" provided by design is enough to cover one's lifetime if not the boat's lifetime. If that's the case, would it be advisable to cut my foil preemptively?

Graham, will you attempt any extra reinforcement when you do your repair?

Mike
SV Trilogy - SM23
Opua, NZ

Patrick McAneny
 

It would seem to me that a bushing or sleeve slid up inside the foil would need to held in a fixed position relative to the foil ,otherwise it would be free to rotate within the foil and not take pressure and wear off of the foil itself. Preventing the sleeve from rotating with the foil could probably be accomplished either by coating it in epoxy while inserting it  or by installing a second bolt 90 degrees and slightly above or below  the original bolt ,drilling a new whole through the foil and sleeve. I will have to check for this problem that until now did not know existed , this is yet another example of the value of this site. This could be a real problem in heavy conditions ,for this defeats the manual furling ,necessitating taking the main down at sea in strong conditions. I am getting ready to drop my masts in preparation to put my boat in a shed to have my boat painted, and will preemptively do this repair . I think a solid aluminum plug may be the way to go .
Thanks for the heads up,
Pat McAneny
SM Shenanigans


-----Original Message-----
From: Mike Longcor (SV Trilogy) <svtrilogy53@...>
To: main <main@AmelYachtOwners.groups.io>
Sent: Tue, Jan 28, 2020 12:10 am
Subject: Re: [AmelYachtOwners] Super Maramu Main Mast Furling foil Sheered

If there is noticeable play back and forth between the main foil and the bolt, is there anything one can do to slow down or minimize the metal-on-metal wear and tear? Perhaps a bushing or sleeve on the bolt would eliminate the gap, but there probably isn't enough space above and below the bolt as all the wear is horizontal.

Waiting until the foil shears itself would probably create some unneeded excitement at sea. Cutting/shortening the foil before it fails seems wasteful. Has anyone tried what Nick has suggested? An internal bushing slid up inside the foil to spread the loads and reduce fatigue seems like a good idea. Or perhaps with proper care the "three lives" provided by design is enough to cover one's lifetime if not the boat's lifetime. If that's the case, would it be advisable to cut my foil preemptively?

Graham, will you attempt any extra reinforcement when you do your repair?

Mike
SV Trilogy - SM23
Opua, NZ

Patrick McAneny
 

I had not seen the photos ,I now see that the sail groove would keep a sleeve from rotating within the foil,I still think I will mill it from solid stock and mill it to fit around the luff groove.
Thanks,
Pat
SM #123


-----Original Message-----
From: James Alton via Groups.Io <lokiyawl2@...>
To: main <main@AmelYachtOwners.groups.io>
Sent: Tue, Jan 28, 2020 8:02 am
Subject: Re: [AmelYachtOwners] Super Maramu Main Mast Furling foil Sheered

One thing that could affect the wear rate of the extrusion attachment hole is the bolt itself.  Check to be sure that there are no threads in contact with the surfaces that bear the torque stresses.  The smooth part of the bolt should in other words be  long enough to allow tightening when bottomed.  It may be necessary to have a custom bolt made to attain the correct length.  One can think of the threads of the bolt as a sort of a file that will chew out a bit of aluminum each time the joint is loaded.  

The internal bushing sounds like an interesting idea.  

James
SV Sueno
Maramu #220

On Jan 28, 2020, at 12:10 AM, Mike Longcor (SV Trilogy) <svtrilogy53@...> wrote:

If there is noticeable play back and forth between the main foil and the bolt, is there anything one can do to slow down or minimize the metal-on-metal wear and tear? Perhaps a bushing or sleeve on the bolt would eliminate the gap, but there probably isn't enough space above and below the bolt as all the wear is horizontal.

Waiting until the foil shears itself would probably create some unneeded excitement at sea. Cutting/shortening the foil before it fails seems wasteful. Has anyone tried what Nick has suggested? An internal bushing slid up inside the foil to spread the loads and reduce fatigue seems like a good idea. Or perhaps with proper care the "three lives" provided by design is enough to cover one's lifetime if not the boat's lifetime. If that's the case, would it be advisable to cut my foil preemptively?

Graham, will you attempt any extra reinforcement when you do your repair?

Mike
SV Trilogy - SM23
Opua, NZ

Karen Smith
 

Here is the detailed write up, of what we did, when we had this issue a year ago. We are quite happy with it!  Amel Mainsail Foil Repair



John Clark
 

Hi Karen,
   Excellent write up. I did s similar repair on Annie (SM37) and agree 100% to use a reinforcing tube for the bolt.  I wound up using JB-Weld in a similar fashion to regular epoxy as you suggested but did not fill the foil with it.  The key as you said is to distribute the load to avoid point sources of stress.  Annie's foil is original and has 3 circumnavigations....but also attentive previous owners so there was only play between the foil and the coupling before I got to fix it. I do question the epoxy mix you used....I tried it and as you suggested I thickened it with mayonnaise.....but it got very lumpy and not well organized....so I figured I over added the mayonnaise and thus thinning was in order so I added some peanut butter...  I don't know what kind of epoxy you used but I could never get mine to work with the mayonnaise and peanut butter.   

   FYI about a year later I, the bad owner, in a moment of carelessness tried to furl the mainsail with a pretty solid breeze and the coupling failed before the foil.  We were downwinding into a channel lines with rock jetties and had a series of turns coming up so I decided to switch to motor and didn't think about the point of sail and wind....and snapped the coupling.  (Amel Martinique had a new one in a week for us) The repaired foil was perfectly fine.   I wonder if Amel engineered the coupling as the sacrificial point of failure?  Important consideration if one were to have one made locally as I was...

Regards,  John
SV Annie SM 37
Brunswick GA....hoping to soon be in the USVI  ;)
  

On Tue, Jan 28, 2020 at 9:52 PM Karen Smith via Groups.Io <karenharmonie=yahoo.com@groups.io> wrote:
Here is the detailed write up, of what we did, when we had this issue a year ago. We are quite happy with it!  Amel Mainsail Foil Repair