I’ve seen at least two cases where a too tight internal halyard put a bend in the extrusion at the very top. That makes it harder to turn the furler,. That’s very similar to what
@Tally Ho describes above, but maybe not exactly the same.
In both cases the sail was many inches shorter thabpn the extrusion, leaving a gap a the top. If the sail doesn’t go to the top of the extrusion, tensioning the halyard too much bends the very top of the extrusion. That makes it harder for the extrusion to rotate around the forestay. I’ve seen that happen.
The way to prevent this from happening is to attach a pendant to the head of the sail. The combined length of the luff and pendant should match the available space on the extrusion. With a pendant, you wont be as likely toover tighten the halyard without noticing it. You get enough tactile feedback to know the sail is up all the way and that it’s time to stop tensioning then halyard.
The two examples I’ve seen of this resulted in permanently bent extrusions. IIRC, both owners had dropped the mast and stored the sail on the furler without easing the halyard. One owner stored the furler and sail in a big PVC tube on the roof of his truck. Without a tight forestay to resist the bending force from the halyard, the extrusion bent more sharply during storage and the bend became permanent. I. Don’t recall exactly how the second owner stored the furler, but in both cases the owner needed to replace the extrusion.
I sell a handful of replacement extrusions every year to replace one that got damaged somehow or other. I always talk to the owner to find our what happened. Despite the many stories I heard over many years I don’t doubt that I’ll hear a new and novel way to ruin an extrusion sometime soon.
Fortunately it’s only $150-$250 to replace the extrusion for a small CDI which would be the likely size found on a trailersailer. Small Cdi furlers are really low priced compared to anything else on the market, even if you are unlucky enough that you have to repLace the extrusion.