Re: [Amel Yacht Owners] Super Maramu rigging loads

James Alton

    I would be curious to know how much tension can actually be applied via turnbuckles and whether it is actually possible to get to 30 percent of ultimate.  The SWL of 1x19 is around 40 percent so if a rig is preloaded to 30 percent it seems likely to me that the SWL could be exceeded pretty easily when sailing loads are considered.  The max compression loading of the spar might be more of a concern to me.  I am not sure of what wire sizes are used on the SM but 30 percent on 3/8" wire would be around 4 tons of tension/compression per wire x 10 or around 80,000 lbs. Total just sitting at the dock..
    The Amel rig has very generous shroud angles due to the chainplates set well outboard and the spar being relatively short so why the need for lots of tension? May I ask why you feel that the Amel rig must be kept very tight and could you provide some actual numbers so that I can understand what you are calling very tight?
   Sueno was tensioned about the same when I bought her as I would have done which I would roughly estimate to be 5 percent of ultimate on the caps and correspondinly less on the shorter shrouds.  The forestay is tighter of course. Her ACMO rigging is original (29 years old) and though it will be replaced this year my surveyor did not find any cracks or failed wire.  The bulkheads and every part of the structure containing the rigging loads looked excellent and I would like to keep it that way. I have surveyed and rebuilt a lot of boats with structural damage in this area but no Amels to date.  I just do not understand the need for rigging on a cruising boat to be tensioned anywhere close to 30 percent of ultimate but I am curious about why some apparently feel that way?  Please provide some technical reasoning behind this position if you can.

SV Sueno Amel Maramu #220

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-------- Original message --------
From: "Richard03801 richard03801@... [amelyachtowners]" <amelyachtowners@...>
Date: 08-11-2016 1:19 PM (GMT-04:00)
To: amelyachtowners@...
Subject: Re: [Amel Yacht Owners] Super Maramu rigging loads


Give the AMEL rig/hull design it is appropriate to keep the rig very tight. The hull engineered to be very tight rig. There MUST not be slack on the Lee side when going to windward. The mast must remain in column at ALL times. No bend fore and aft or side to side. Bill's issue was a "rigger" set the head and aft stays like it was a production boat. That is not appropriate per AMEL. 
The general rule is tighten each stay keeping the mast in column until it rings when tapped with a wooden hammer handle. If goes thud take a wrench to it. 
Hope this helps. 

Fair Winds Smooth Sailing 
Capt Richard Piller
Newport RI 
Cell 603 767 5330

On Aug 11, 2016, at 11:47, Lokiyawl2 lokiyawl2@... om [amelyachtowners] <amelyachtowners@...> wrote:


   So you have preloaded your rig by your estimate to as much as 30 percent of it's ultimate strength? That may well be more load than the rig will see even under severe conditions.  The preloading effectively reduces the remaining safety factor of the max compression loading of the spar... Also consider that plastic deforms over time under load.  Ever noticed how an improperly blocked fiberglass hull can take a permanent set when too much load is concentrated at one point of the hull for a long period of time?  Yes, the structure is strong but push or pull hard enough for long periods and deformation will occur.  On a cruisng boat I tune to keep the spar to remain straight in all conditions (verified by loading up the rig and sighting the sail track) but tight enough that the lee rigging is not excessively slack.  If the boat is to be at rest for an extended period I reduce rigging tension. Hopefully o thers will comment.
SV Sueno, Maramu #220

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-------- Original message --------
From: "william_maffei@... [amelyachtowners]" <amelyachtowners@...>
Date: 08-11-2016 10:57 AM (GMT-04:00)
To: amelyachtowners@...
Subject: [Amel Yacht Owners] Super Maramu rigging loads


Hey everyone - 

I know this topic has been addressed before. I have recently tuned my rig and it was crazy to me to the amount of work that was involved. This traces back to a previous post I had made about the forestay being wobbly. The problem (which I never thought) was the rig. Needed to be tightened (a lot). The pin actually came loose while furling the jib and that was the only problem. Now, I had my rig professionally serviced and tuned and as we all know this is a controversial topic among "professional" riggers without Amel experience. So I did the job myself with the help from another owner. My rig is so tight now you could play music off it. Actually when you tap the backstay it sounds like George Lucus used this to replicate the blaster sounds from Starwars. HAHA. Anyways, I called my rigger and he was very interested to come take a look. He was shocked... I mean literally shocked. Told me it goes against everything he has ever learned about rigging boats. His gauges were not even able to read the loads of the stays. Told me that other boats would have collapsed on themselves under the loads but at the same time agreed to the tensions. His question and the reason I am writing this is to find out if anyone has numbers for him. I guess the average numbers are 15-30% of the break load... (???) Can anyone chime in on this topic? Provide some numbers I can write down and relay? Any stories about tuning their rigs? Hope all is well and fair winds!

Bill Maffei 

SM #195

It's all Good

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