Re: [Amel Yacht Owners] Re: rig tuning

Ryan Meador

Hi Eric,

Thank you for the advice. That's my plan whenever I unstep the masts. I'm sure there is a dead spot in the radar, but every other Amel seems to get by with it. I'd rather not have the weight on the backstay.

I don't think that is the cause of my present problem, though. Now that I've tightened the backstay, the radar doesn't move at all. I don't think it is contributing to the pumping. Certainly, Frank had it tuned such that it wasn't a problem, so it's possible.


Ryan and Kelly
SM 233 Iteration
Boston, MA, USA

On May 27, 2018 3:36 PM, "eric kimberlite@... [amelyachtowners]" <amelyachtowners@...> wrote:

Hi Ryan,
I would ask Questus if they can sell you the Questus mast mounting kit for the Questus. Mine has been working fine on the Mizzen mast for 16 years.

Frank mounted the dome on the backstay as he said he gets a dead spot behind the mast on the radar. I thought his mount as odd.

Amel rigging is ridiculously tight the cap stay is like a piece of rebar.
Good luck with your rig tuning.
Fair winds,

On Sun, May 27, 2018 at 10:15 AM, Ryan Meador ryan.d.meador@... [amelyachtowners] wrote:


I tackled this problem yesterday, and it did not go as planned.  My main mast is now pumping fore-and-aft in a wide range of wind speeds with the wind on the beam (I haven't been able to test any other wind directions yet).  The top of the mast seems to stay still, and there is little to no motion at the lower spreaders; the pumping is centered near the upper spreaders.

Before starting, I reviewed advice from this list, the Selden guide, Brion Toss's Rigger's Apprentice, Ivar Dedekam's Illustrated Sail and Rig Tuning, and other online sources.  I thought I had a vague idea of what I was doing..  Unfortunately, every one of those guides assumes you're starting from a freshly-stepped mast, so I had to improvise to apply the procedure to tune mine in-place (I couldn't use the folding-rule method because the stays were already under an unknown load).  Here's what I did:

  1. removed a slight forward tilt of the uppermost part of the main by tightening the backstay, which, as I suspected going in, was the loosest of all the stays -- the previous owner installed the radar on a Questus backstay mount.  I will probably put the radar back in its traditional place when I next unstep the mast.  I did not adjust the forestay.
  2. removed a slight lateral S curve
    1. tightened the starboard cap shroud
    2. the port intermediate shroud
    3. the starboard lowers
  3. I tightened all four lowers one turn just because they all seemed a bit looser than what was described on this list (they now make a sort of tone when hit with a wooden hammer handle, but they don't quite resonate)
  4. tightened mizzen starboard cap shroud one turn to correct slight bend to port
  5. tightened all four mizzen lowers one turn because they seemed loose
  6. loosened port mizzen backstay half a turn.  I know the backstays are supposed to be fairly loose and the port was a bit tighter than the starboard one
The masts were now in column and looked just about perfect.  When the pumping first became apparent (when the weather turned, of course), I added a turn to the main's forward lowers in an attempt to induce a minuscule pre-bend.  There was no perceptible difference in the mast shape, but there may have been a minor difference in the amount of pumping.

Does anyone have experience with this problem?  I'd greatly appreciate some advice on how to fix it!  I'm almost desperate enough to try a non-Amel-familiar professional rigger.

Ryan and Kelly
SM 233 Iteration
Boston, MA, USA

On Wed, May 16, 2018 at 6:25 PM, sangaris@... [amelyachtowners] <> wrote:

Hi Steve,

Yep, that's the booklet. Check out the "Folding Rule Method" of tensioning.
Sounds reasonable that the existing rig is loose due to stretch. That makes it pretty easy to tension back up - just count the turns you take on starboard and do the same number on port, assuming the mast is in column to begin with.
Craig SN68 Sangaris, Ft Pierce FL

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

Steve, thanks for the data, that's very helpful.

Craig, thank you also for your advice.  That's a great rule of thumb.  I have The Complete Rigger's Apprentice, which discusses rig tuning a bit, but not as much as I'd hoped before I bought it.  I will definitely read the booklet you mentioned (which is perhaps this free PDF?).

I suspect the slight looseness in my rig is because the wire has stretched over time..  It was quite tight when I bought the boat, and I think the boat hadn't been sailed much by the previous owner after he replaced the standing rigging.

SM 233 Iteration
Boston, MA, USA

On Wed, May 16, 2018 at 12:40 PM, sangaris@... [amelyachtowners] <amelyachtowners@...> wrote:

Hi Ryan,

I'd recommend Selden Mast's booklet Hints and Advice on Rig Tuning - you can download the pdf. They give a neat "folding rule" method (pg 32) of determining tension based on the fact that 2 meters of any diameter of 1X19 wire stretches 1mm for each 5% of breaking strength applied.

So, for example, if you want to tension your 12mm cap stays to 20% (Amel tight, maybe!) just tighten them until 2 meters stretches by 4 mm. That stretch will give you about 5600 pounds of tension, as the breaking strength is about 28000.

The Loos gauge doesn't handle wire over 10mm (actually 9.5 mm as it's rated for 3/8) and only goes up to 4500 pounds. That's why the results Nance and Underwood gave Steve Morrison in his post just show "very tight" for his 12mm stays.

After you get a sense for "very tight" you'll get to trust just feeling the stays and being able to judge if they're right. And use Joel's suggestion to go out, sail upwind in a good breeze and see if your lee shrouds are at all slack. If yes, they're way too loose. Oh yeah, and recheck after a while as the wire will stretch over time.

On the headstay there is a turnbuckle screw under the furler. ACMO just calls it "special" , as it's shorter than standard ones so the furler can be closer to the deck.

Have fun tuning!
Craig Briggs SN68 Sangaris

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

Hi all,

I'm about to embark upon tuning up my rig, which I feel is a little loose, but I'd love some guidance on how to do that.  I've scoured the archives of this list and found many mentions of guides from both Joel Potter and Olivier Beaute, but I haven't been able to find them.  The best guide I've found thus far is this one.   Can anyone link me to the gold standard(s)?

Also, has anyone done the tuning in a more scientific way, with a Loos Gauge?  I'm struggling to understand via qualitative descriptions just how tight is tight.  I think a quantitative measurement would be very helpful.

And finally, how does one adjust the forestay tension?  I admittedly have not studied it in depth, but I didn't see a turnbuckle or any other obvious mechanism.

SM 233 Iteration
Boston, MA, USA

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