Re: [Amel Yacht Owners] Slowing down in increasing winds


Danny and Yvonne SIMMS
 

Hi, you will note that both the static main-boom Vang and the main and mizzen adjustable preventers are laid nylon rope, the most elastic available. (if used on a swing mooring the allowance for stretch under maximum load is 33% of length) The static vang caused me some mocking amusement when I brought my racing sensitivities to my Amel. Of course I was wrong. Its length is perfect. Because it is attached to a fixed tongue at the base of the mast when the boom moves out to the broad reaching then running position the vang tensions slightly, more the further out the boom goes. Until the sheeting is beyond the traveler it is slack, then when needed it takes up. Who wants to be messing with vang tension. Henri, I again salute you. However whatever your mainsheet is made of it is high risk to gybe with the sheet slack and uncontrolled, you may get away with it sometimes but eventually.......

Regards

Danny

SM 299 Ocean Pearl 

On 05 June 2018 at 11:28 "James Alton lokiyawl2@... [amelyachtowners]" <amelyachtowners@...> wrote:

 

Bill,


   Thanks for your input and advice.  That is a good point about being sure to bring the traveller all of the way to the leeward side when sailing at an angle that could possibly result in a gybe.  

    I am curious about whether the boom on your boat can actually hit the backstay?    Have you tried raising it using the topping lift, then swinging it back and forth to see?   The main boom on my boat clears the backstay even when lifted so that it is perpendicular to the backstay, but not by much!  

   On the subject of shock loads (such as from jibing) and elasticity, I came across this snip from a forum response by Brian Toss whom I feel knows his stuff pretty well.  

" Shock loads are relative to acceleration and elasticity. They can be quantified and included in design load calculations if desired. The short form here is that the materials you are likely to use appropriately are also appropriate for any shock loads, if they are scaled to the design load, times a safety factor. As a counter-example, I've seen main sheets and vangs break gear when owners ill-advisedly replaced Dacron with HM line.

Brian’s complete post can be found at:   http://www.briontoss.com/spartalk/showthread.php?p=5662

Best,

James
SV Sueño
Maramu #220

  




On May 30, 2018, at 7:12 PM, greatketch@... [amelyachtowners] < amelyachtowners@...> wrote:

I'll have to think about the gooseneck, and how it changes things...  a good thought...  And I agree the elasticity of the mainsheet can help... but only to a point.  If the mainsheet stretches enough to allow the boom to hit the shrouds, more problems can occur than are solved.


There is another really important piece of the puzzle, that someone else mentioned earlier in this discussion.  The position of the traveler has a huge impact on the amount of damage that can happen in a gybe.  

If the traveler is centered, and the boom is eased out only with the mainsheet, a gybe can be really dangerous.  With that much mainsheet out, the boom can rise when it crosses, when the mainsail goose-wings around the mast.  It can rise enough to actually hit the backstay as it comes across.  If the boom was out touching (or very close to touching) the aft lower shroud, when it comes across i t can impact the aft lower shroud on the other side.  Both of these scenarios are potentially disastrous both to the boom--and the rig itself.

If the traveler is all the way over to the leeward side, then these problems can't happen, or at least are minimized, because the mainsheet is so much shorter, and the boom is stopped halfway across, before it can get really moving.

One of the things I really love about the Amel set up is that the traveler is long enough to actually be really useful as a sail trim tool. When sailing anything upwind of a beam reach, we  adjust the traveler far more often than we do the mainsheet.  If we are sailing downwind, the traveler is always (no exceptions--ever) eased down to the leeward side.

There are aways two parts to preventing damage in an accidental gybe.  First is avoid the gybe in the first place.  A nice idea, but it will happen to e verybody.  The second part is to be sure the boat is set up so damage is avoided or minimized.

Bill Kinney
SM160,   Harmonie
Deltaville, VA, USA

 

 


 


 

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