Melges 24 White Paper on the Systemic Forestay Issues related to the 7x19 Jib Halyard
9 November 2024
Melges 24 White Paper on the Systemic Forestay Issues related to the 7x19 Jib Halyard
- Created by the International Melges 24 Class Association Technical Committee
November 9, 2024
Background:
Earlier this year, the IM24CA Technical Committee started receiving reports (complaints) documenting the premature failure of the current supply of 7x19 stainless steel wire rope halyards. While it is well-known that the 7x19 halyards used in this application require routine inspection and replacement on a regular basis, it seems that the current supply of 7x19 is not as robust as past supplies. More troubling, however, is the current 7x19 supply seems to be failing with the inner core of the wire often breaking first and this is not visible without unraveling the wire. This means that routine visual inspection looking for bird caging and broken individual wires will not necessarily reveal the issue putting even the most diligent teams at increased risk.
After consultation with Zenda, they reported that they were aware of the problem and have already tested a number of different suppliers to try and resolve the quality expectations of the fleet. Sadly, to no avail. This seems to suggest that the supply of 7x19 wire rope is being dominated by a single manufacturer controlling the market through distribution.
While we are concerned about the quality of wire supply, rig loading seems to be playing a significant part in the reported failures. A lot of teams are going well beyond the 25 turn limit suggested by the manufacturer and most rig tuning guides.
To give perspective on this issue, it was reported that a lot of the top teams competing at the 2024 World Championships in San Fransisco were replacing their 7x19 halyards after a single day’s sailing, such was their lack of trust in the quality of the wire.
While the class has been lucky that no one has been seriously hurt as a result of a failed forestay, this is now clearly identified as a safety issue in addition to yet another unwelcome increase in the cost of participation. As it is the Technical Committee’s responsibility to investigate and possibly find ways to address concerns like this, it was decided to propose a rule change for 2024 to ban the use of the original 7x19 halyard design going forward in favor of the newer fixed forestay design that was approved for class use in 2008. As predicted, this proposal created some spirited commentary from those in attendance at the annual Technical Committee meeting held earlier this fall. As a result of those discussions, it was suggested that the proposal was being tendered without the vast majority of the membership even being aware of the issue and as a result the Technical Committee withdrew the proposal in favor of starting with a full report, which is the purpose of this white paper.
Current Class Approved Forestay Systems:
The issue with the 7x19 halyards is not new to the class. 7x19 does not respond well to rotational or twisting loads caused by furling the jib which eventually causes the wire to bird cage and break. This has been a concern for a long time and in 2008 the class approved an alternative design utilizing a 1x19 “fixed” forestay in hopes the fleet would convert to a safer and less costly to maintain system. The fixed forestay system replaces the original system with a conventional forestay which is attached to the mast using a Gibb T Fitting (or similar) with a female backing plate installed in the mast above the factory halyard sheeve. The stay is fitted with a sliding furling swivel which is hoisted using a Dyneema halyard using the original halyard sheeve. The stay terminates at the mast with the same furling swivel used in the original system. As 1x19 handles torque much better than 7x19, bird caging is eliminated. While many in the fleet did test the system shortly after it was approved, it was eventually discovered that the original system was actually faster and easier to use, especially in the higher wind ranges.
Understanding the wire - 7x19 represents the number of strands and wires each rope contains. The 7x19 variant includes 7 strands or bundles with 19 wires in each, giving the rope 133 wires. When you do the math, a 7x19 cable has over 2.5 times the number of wires used in a 7x7 construction which is another flexible wire rope alternative. When compared to ropes with a lower wire count, higher count wire ropes allow for easier bending, which makes it ideal for operations such as our halyard. This is why the designer (and the class) originally mandated 7x19 over 7x7 wire rope.
While galvanized 7x19 wire rope is actually stronger than stainless steel and has been tested by the class to reasonable effect, the corrosion issues, especially in salt water, makes its use less than ideal which is why it is not approved for use.
The original halyard design ingeniously utilizes the inherent stretch properties of the 7x19 wire to auto rake the mast aft as the shroud tension is increased. To understand this as an example, our 7x19 halyard will stretch approximately 13mm more than an equal length of 1x19 when loaded to 25% of its breaking strength. Obviously to increase the rake you simply tighten the shrouds and the 7x19 stretches allowing the mast to rake aft. It is a great design, except for the torque created by furling the jib.
The pros and cons:
· All masts manufactured after 2009 were mandated to have the female backing plate (receiver) installed when the mast was built. This means the retrofitting of the fixed forestay is simply a matter of adding the stay (complete) and setting up a 3:1 purchase system for the new jib halyard (similar to that used for the main halyard). However, masts made before this have to have the female backing plate installed to utilize the system. This is an additional expense and obviously the backing plate must be installed properly.
· The fix stay system is fitted with an open barrel turnbuckle which is used to manually set the stay length and by extension the rake. While the 1x19 does stretch a little, it does not stretch enough to effectively rake the mast as the shrouds are tensioned up. This means the stay must be lengthened as the wind speed increases. Typical tuning guides suggest this is done in 4 steps of ½” each with each step requiring 6 full turns of the turnbuckle. Once you are over 15 knots you are fully raked at step 4. This must be done on the bow and requires 3 hands. One to hold the furling drum (or the bottom of the turnbuckle), one to turn the barrel, and another to hold the stay from turning. This can be improved by making a simple tool to prevent the furling drum from turning. In addition, the jib must be lowered a few inches to allow access.
· The fixed stay system allows for the jib to be easily removed if fitted with a zipper luff. And as it is fitted with a halyard, the halyard can be easily adjusted in the cabin at the compression post using the purchase system. The jib tack is set using a strap, so the jib is set at a constant height which creates repeatability for the jib car settings.
· As the rake is set by the forestay length, which is adjustable, the stiffness of the boat has less impact on rake and rig tension. This effectively means that older or softer boats can be more competitive with less rig tension.
· The robustness of the fixed stay is quite impressive. Current users are reporting using the same stay for over 10 years. The bronze open body turnbuckle barrel does wear however, and replacement is required every 4 or 5 years depending on use, not unlike the shrouds.
· With the backing plate installed above the original halyard sheeve, the forestay gains some leverage, and this does affect the backstay’s ability to bend the mast. This results in a heavier backstay adjustment which could be offset by increasing the purchase, sadly that is not within current class rules.
· As older spars require modification, converting the class to the fixed stay will create a burden on the older boat owners. And converting will require an upfront purchase. This obviously would be easily amortized as the stay does not need replacing unlike its 7x19 counterpart.
· The fixed stay system has the advantage of being more cost effective in the long run and being much safer.
Other alternatives and comments:
The Technical Committee has been proactively looking at this (and other issues) with the boat for some time. Two years ago, we approved an application to experiment (see Section 9 of our constitution regarding experimental testing) with a Dyneema halyard. The system utilized a custom Harken upper Halyard swivel that allowed the halyard to have a 2:1 purchase at the top using the fixed fore stay receiver. It also featured a magic box purchase system at the compression post to control rake. The jib hoist halyard runs down the luff inside the zipper and is terminated at the tack not unlike the current Cunningham design. Initial testing showed promise, but the system was still plagued by halyard wrap when furling and the fact that Dyneema has chafe and UV damage issues that effectively made it no better than current systems. There was also not a lot of control of stay length which might have been in part because of the construction of the Dyneema. There is still the opportunity for more study with this setup including increasing the length of the 1x19 stay so that there is less halyard to twist at the top and finding more durable synthetic halyard materials.
Recently we were introduced to a Stainless Steel 5mm diameter 19x7 wire rope cable. This is 19 strands of 7 wires to be clear. This is commonly used in crane hoists but up until recently, it was not available in smaller diameters. This cable is specifically designed to accommodate torsional loading and twisting. A Section 9 application has been granted and we are waiting for some updates. That said, expectations are that it will not stretch to the same degree the 7x19 does which means that manual adjustment of the rake will also be required. And if that is the case then how is that any better than the current fixed stay option?
Finally, it has also been suggested that the old system is fine the way it is with areas of the world reporting no issues at all. Some claim their supply of 7x19 has seen no difference at all. I would point out that this might be the result of existing supplies of better quality 7x19 still working its way through the distribution system. And some areas of the world will see their fleets sailing in less wind which in turn makes it less likely the issues will be as prevalent as in a place like San Fransisco. That however changes nothing as we do have boats sailing in venues that regularly approach the maximum allowable upper wind speed limit of 25 knots. We could always consider lowering that upper wind speed limit down to say 18 or 20 knots which would also resolve the issue… but somehow, I doubt any of you would be interested in that!
Epilog:
Last weekend, the annual Bushwhacker Cup was held in Pensacola FL. We received a report from the Canadian Class President Dan Berezin sailing CAN 629 who inherited a 3rd place finish. He reported that wind speeds were in the 15-knot range with wind gusts into the low 20s. After only 8 races (2 days) on a brand-new halyard, he was concerned to find his 7x19 almost entirely broken at the end of the event and was very fortunate to make it back to the dock with the rig still standing. He also noted that USA 420, who sailed a brilliant 1,1,1,2 on day 1 lost their mast upwind in R5. USA 420 was apparently running a new Ceilidh mast with its newer spec halyard sheeve while CAN 629 was running the black Southern Spars rig with the standard halyard sheeve. This would seem to suggest that the halyard sheeve design is not entirely the issue. These two halyards came from different suppliers (one was OEM from a brand-new roll of supposedly US manufacture). We suspect 629’s halyard was of Korean origin. CAN 629 reported being up 30 turns.
As a result of this weekend, we now have one major USA based rigging supplier who is stepping up with more experimentation on a direct replacement using a pre-stretched Dyneema alternative version. Some of this testing might be complete as early as Bacardi 1. We have also approved testing of the 19x7 for the same event.
Members may be wondering about the cost of the fixed forestay conversion kit, and we did reach out to Zenda to get a rough guestimate. While the original kit was supplied by Southern Spars, we think a complete 2024 kit for a pre-2009 mast will cost approximately $800 USD. It will also require approximately 3 hours of labor to install the female receiver which is epoxied and bolted mechanically in the face of the spar. Zipper luff jibs are not made on a regular basis by any of the major lofts and with many teams relying on used inventories, this is also a consideration if for nothing more the timing of an implemented change. Retrofitting a used jib to a zipper luff is possible but it is not the easiest job to get right. But it is also possible to use a standard jib with the fixed forestay, it is just not as easy to remove the sail.
But what is now clear, this situation is quickly becoming untenable. We are hopeful that we finally have some top teams committed to experimenting with alternative halyards so we can get some real-world feedback. Still, it remains to be seen whether any of these alternatives will be an improvement over the fixed forestay system.
In closing, I will add that the class has known about this issue for a very long time. Its impact on the fleet, ebbs and flows but clearly, it is an issue now. Just ask the very disappointed owner of USA 420. And I will point out that the class already has a solution approved for use. The Melges 24 is a strict One Design Class, yet it somehow allows for two completely different forestay systems. One is reliable, safe and cost effective. The other is prone to failure and apparently in need of replacement with increasing frequency. I keep wondering how this is even a question.
Mike Gozzard (CAN)
IM24CA Technical Committee Chair