Not surprisingly my clew attachment point has worn a bit to the degree there is now some looseness with the shackle pin. I replaced the shackle with some dyneema and it works but wears due to the sharp edge of the hole in the casting.
I was thinking I could remediate the by using something like JB Weld. as a bushing. I can just leave the shackle in place and use dyneema to connect it to the sial. Since both surfaces are smooth wear should be minor.
Other ideas involve a pad eye but the load would in the lateral. I did look at a Wichard eye and welding a stainless ring to the head of a bolt. Both would require a bushing in the hole as well.
Would smoothing the ridge on the casting hole be enough to mitigate the dyneema line wear??
My current boat came with the clew attachment point enlarged and a stainless steel bushing inserted (I’m guessing somehow press-fitted) that fills the enlarged hole and protects the aluminum boom end casting from the shackle pin wear.
My previous boat had a similar problem, and I dealt with that by using a long length of dyneema to do a lashing which wrapped around the end casting on both sides of the fastenings for the topping lift and mainsheet block. I don’t have a picture of that, but here’s a picture of a similar lashing that was done for the choker block on the forward end of the boom.
Dyneema doesn’t like any sharp corners or or corners of any kind. I rounded the hole edges to a large radius and polished the hole smooth. The Dyneema soft shackle at the clew has so far lasted two seasons. It looks flat and squished where it contacts the casting and also the sail eye but doesn’t look cut or frayed. A soft shackle is just a loop and is easy to move so a different part of the line is contacting the casting.
I guess you could use a thimble to protect the Dyneema from the casting edges but then the casting will continue to wear. In this case you might as well just use a steel shackle.
The soft shackle I made is about 6 inches long (uses 24 inches of line) so replacing if it becomes worn is no problem. Much easier than fixing the casting.
Hi Thor. I wonder if modifying a stainless steel thimble would give you what you need at that spot.
Something like this, cut to size and pressed into the spot, perhaps with a spot of JBWeld to hold it in position? 1" Standard Duty Thimble - Stainless Steel (304) (riggingwarehouse.com)
I substituted a Wichard eye bolted to the boom with the eye underneath to allow for slightly more lift. It proved satisfactory for a decade or more until I changed rigs. Whatever you do continue lashing the boom to the clew. It is a safety measure that allows you to slash the lashing in an emergency.
My boat came to me with a long shackle that had worn groves in both sides of the stern end of the boom. I was also having a problem when tacking, the topping lift would get hung up on the roach, spoiling the sail shape. I had read that the original intent was to have a lashing attach the clew. When I noticed that even with full choker applied, I still had travel room between the front of the mast and the forward end of the boom - I was able to accomplish two fixes. I removed that shackle from the stern end of the boom and tied in about eight inches of lashing to the Clew. Then to get proper sail flattening I adjusted the choker line where it attaches to the pad eye on the mast - by a ratio of 2 to 1. My topping lift no longer gets hung up on my sail roach.
Herb G. Huber, MISTOFFELEES N/S 30C#91
Lake Huron Nonsuch Association
