According to the manual for the 26C the length is 9’8” of 3/16” of 7 x 9 stainless with an eye at the upper end and an eye and shackle at the lower end. The manual does not specify whether the length includes the shackle. The shackle is intended to allow the boom to easily be disconnected and lowered to the deck.
If the length of your current hangers work well with your sail you should stick to that length. There are variations in the cut of the sails in the fleet so you want a length that works with your sail. My belief, not supported by any technical training, is that shortening the cables will increase the angle of the boom with the result that hardening the choker will put more tension on the leech of the sail and less on the foot. Conversely lengthening the hanger will result in more tension on the foot and less on the leech. I also suspect that small changes in the length will not produce any noticeable difference. If the boom hits the choker cheek block the rubber bumpers are likely to degrade more quickly. If you are a member of the INA you can consult with Mike Quill, who can let you know if I am correct and the range of lengths you have available without impacting the function of the choker.
My question to you is: What are the benefits you are hoping to achieve by going to Dyneema? UV penetrates and damages the surface fibres of Dyneema. The depth of penetration is about 1/8”. On 3/16” line that is effectively the entire thickness of the line. This means you can’t go smaller than 3/16” so you do not gain an aerodynamic boost and there will be little weight savings, may 1.5 pounds. Coated 7 x 9 stainless wire will long out live the Dyneema.
I would assume the length does not include the shackle.
I share Mark’s intuitions about the effects of shorter or longer hangers
Duration of dyneema under UV exposure is very sensitive to your latitude (since that heavily impacts actual UV exposure). My recollection is that Practical Sailor recommends giving uncovered dyneema 3 years in the Caribbean, but suggests it may well last up to ten in Northern Europe.
The safest choice if using line rather than stainless wire would be to use a dyneema-cored and polyester covered line, or planning on a regular inspection schedule.
I’ve also seen warnings that you should use closed thimbles with dyneema splices rather than the cheaper eyes meant for stainless wire. Those are basically a curved channel bent into shape with a gap between the ends. That gap can end up chafing the eye.
I’ve been working with dyneema for awhile, and like it for many things. I haven’t developed the skill and acquired the equpment yet to ensure a line of an exact length, although I can probably get within a few inches. Although dyneema doesn’t stretch after being loaded, there is a significant difference between the length of a 12-strand loose dyneema line and one that’s being pulled 'til it resists. If you think about its resemblance to a Chinese finger trap, this makes sense.
Thank you both. Truthfully the driving factor for using dyneema is time and convenience. I’ve just returned from traveling and eager to get the boat launched for the season. I don’t have a rigger available and I don’t have the tools to work with stainless cable. I can however get the dyneema quickly and I’m good with the splicing. I’m mid-coast Maine with the boat exposed to sun 4 months at most.
RE: length. That makes sense, and it is helpful to think about.
I am leaning toward making the dyneema hangers very close to the original length, with only a small amount of adjustment available to equalize the two sides. That should preserve the original balance between foot and leech tension and avoid pulling the boom into the cheek block or accelerating wear on the rubber bumpers.
I also could add a little adjustment with lashings, but it sails fine as is. And, the dyneema might be temporary for a season or two until I can get stainless made up.
I had my mast gone over by a rigger when I bought it in March, 2023. He said the boom hangers were rusting and needed replacement. He strongly recommended Dyneema. He wanted to replace the 1/4" stainless with 1/4" Dyneema. I’m standing there in the yard going uh, uh, what’s Dyneema? Turns out I was aware of other high tech fibers so I asked about UV. He said it should last around 12 years. I figured the outer layers would be most affected, and even with full penetration the degradation would be percentages per year, so I had him go up to 5/16" He inspected them in early 2025 and they still seemed “fine”. But he replaced the topping lift with stainless. Hmmm…
It seems like up in Maine, and with your shorter season, you should get quite a few years on the Dyneema if you just take it up one size from the minimum.
Different rope manufacturers make different variations of the original Dyneema. For example, New England Ropes HTS: “HTS-75 is a 12-strand Dyneema® SK-78 line that has extremely high tensile strength and ultra-low elongation. Unique Marine-Tech coating enhances durability, improves fiber-to-fiber abrasion resistance and protects it from harmful UV rays. It floats. Applications: Cascade lines, halyards, wire rope replacement, cunninghams and vang systems. Stretch: 0.70% at 20% of breaking strength.”
For the hangers, something like this should serve you well. The biggest challenge will be getting the length correct and compensating for stretch. You could accommodate that by starting with a longer shackle and replacing it. Or, ironically, including a turnbuckle. My wire hangers are only 5 years old and the mast comes down every fall, so it will be a while, but I will likely replace them with Dyneema.
Jeff, sounds like you have good reasons to switch and the New England sounds like a good choice. I have read that covered Dyneema is more (way more) difficult to splice than bare.
The splice for a covered dyneema line is harder to learn because pictures of the intermediate steps make it look like everything is going all over the place, but if you follow the steps slowly, it’s not horribly hard to perform.
My proof for that claim is that I was able to do it.
Always a good idea to replace the hangers before they break.
My original hangers were on the boat 25 years. They were in bad shape and were rusty and starting to fray.
New hangers from Mike Quill were heavier wire. These are heavy yes but a bit more weight here will make no real difference. What I really like about these are the shackles at the boom end. They are slightly too big to fit in the wire eye/thimble and I had to hammer them in (this had to be done on the ground but I didn’t learn that until the mast was up), and the pin is also captive. So there is no way you can lose a shackle or a pin while you are up on a ladder attaching them to the boom.
Also, if you are trying to open or close the leach of the sail by changing the angle of the boom, it’s much easier and more effective to ease the sheet or just pull a little topping lift to open the leach.