Rob’s comment about not seeing the need for dyneema got me to re-read the whole thread.
As Curt Danforth pointed out, 5/16” rather than 3/8” is what’s specified for N26 reef lines.
One other potential cause no one’s mentioned yet. As the reefing lines are run forward along the boom, they’re routed through the same eyes used to hold the sail jacklines. Depending on how those jacklines are fastened, they take up a little to a lot of the available space inside those eyes. If you have overly-thick reefing lines as well, the two will create friction against each other running through those eyes.
If you have an adjustable topping lift that’s been rigged to run forward, as well, then the space inside those eyes is doubly crowded because it’s got two lines running through it. The late Murray Cressman, I think, manufactured upgraded eyes with a bar separating the lines. Some boats have those. I suspect most don’t. Without them, the two lines can rub against each other.
So, in the worst case, you can have fat knots from the jacklines rubbing against two fat lines that are also rubbing against each other. If those lines are also old and stiff, you’ve got a perfect storm of friction.
Bottom line: use the specified 5/16” inch line, keep it clean and replace when stiff, follow Brian’s recommendations for reefing procedure. If that doesn’t solve it, take a look at whether the way your jack lines are attached to the guide eyes to make sure they’re not crowding the reef lines passing through.
I’d thought at one point of using dyneema to solve the problem on my boat, but it turned out to unnecessary once I looked at these other issues.
That said, high tech lines are fun, and it could be argued that consideration alone is sufficient reason to use them.
– Bob