Re: [Amel Yacht Owners] Roller Furling Questions


Beaute Olivier
 

Hello everybody,

a few words about the genoa furler. I'm using shorcuts, so, feel free for more questions.

There has been several kinds of genoa furlers installed on the Maramus, Sharkis, Mangos, Santorins and Super Maramus, and until roughly 2002, their manual furling sheave was attached to the foil with aluminum rivets covered with silicone filler (mainly to avoid the possibly reamaining steel part inside the rivet to become rusty). The reason was first that it was an easy way to do it (rather than screws and inserts).
The second reason is that it had to be easily replaceable and AMEL did not change it for a long time because it was just working fine like this.
Then came the questions (from the clients) of replacing the forestay (which did not come for the first 20 years...) and yes the sheaves were very often found to be very hard to pull out the stainless steel shaft.

These rivets were not meant to be taken down as long as the sheave could be pulled out of the stainless steel shaft of the furler. But after 5 years, both parts were seized and the only way to take down the furler was to drill the rivets, and then take the furler to a machine shop to hydraulicly press the sheave out of the shaft.
So, many people drilled the rivets if they wanted to service the furler or replace the forestay. Some have replaced the rivets with alu rivets, or with monel rivets (which creates a galvanic couple with the sheave/foil made of aluminum) or with stainless steel screws, installed in stainless steel tapped inserts. This last solution was also developped by AMEL to strengthen the connection between the foil and the sheave, (to avoid the foil to shear, but at that time, using a new kind of sheave (split in two halves).

However, I'm still convinced that the aluminum rivets are strong enough for a regular use of the furler.
Of course, if you overload the furler (like furling without easing the sheets), or, even worse, if you sail without enough halyard tension, then you will overload this connection.

Sometimes, because the aluminum of the foil is too much damaged (the holes being wider) you just can't put new rivets and you need to find another solution (stainless steel inserts or shortening the tube). In that case, stainless steel screws in stainless steel inserts (inside the foil's channels) is a good solution but needs grease in order they can be easily taken down.

Hoping this will not add more confusion to this (rather) simple topic...


Have a good day.

Olivier.




On Wednesday, July 5, 2017 6:23 PM, "'Bill & Judy Rouse' yahoogroups@... [amelyachtowners]" <amelyachtowners@...> wrote:


 
FYI, I don't see the need for shear at this point in the design and suspect that was the reason given originally for the choice of rivets. 


CW Bill Rouse
Admiral, Texas Navy
Commander Emeritus
Amel School www.amelschool.com
720 Winnie St
Galveston Island, TX 77550
+1(832) 380-4970

   

On Jul 5, 2017 03:20, "Danny and Yvonne SIMMS simms@... [amelyachtowners]" <amelyachtowners@...> wrote:
 
Hi Craig
I too note the points re sheer. However  as you note stainless screws are being used which obviously have high sheer strength. Monel rivets sheer strength is up there with stain less and have two great advantages. No corrosion as they are inert, and ease of use. That is no drilling and tapping of threads.
Regards
Danny
SM 299
Ocean Pearl
On 05 July 2017 at 08:47 "sangaris@...[ amelyachtowners]" <amelyachtowners@yahoogroups. com> wrote:

 

Hi Danny,
Then again, it may be that the Captain purposely used softer Aluminum rivets as a safety so they would sheer before anything else broke. Kind of like a sheer pin on an (older) outboard motor prop. Several o f us have posited that idea, although I don't think we've gotten a definitive reply from someone like Olivier Beaute. In any case, it seems a reasonable and conservative approach rather than harder stuff like monel and stainless steel Allen screws. (Yes, I did read the posts that Amel Matinique is using the ss Allen screws. Lots of ways to skin a cat, I guess.) 
Cheers,
Craig Briggs, SN#68 Sangaris 

---In amelyachtowners@yahoogroups. com, wrote :

Hi.
If you use rivers monel are the best. Inert. That is no corrosion and very strong, Ali are  far too soft and sheer easily.
Regards
Danny
DM ,299
Ocean Pearl
On 03 July 2017 at 13:18 &#3 4;greatketch@... [amelyachtowners]" <amelyachtowners@yahoogroups. com> wrote:

 
Mark,

Stainless screws are fine if you use something like Tefgel to isolate them.

Even if you do go with aluminum screws, use Tefgel. The difference in alloys is enough to cause trouble, and the Al screws are not strong enough to remove if there is even a trace of corrosion. Talk to anybody who head had to remove the Al screws Amel used to attach the boom tracks!

Bill Kinney
SM160 Harmonie
Boston, Mass


 
 

 


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