A fellow TI owner visited me today on the way back from a day of sailing. We were talking about various things related to the TI and he commented that his mast pieces wouldn’t stay tight - something about them slipping and the sail getting a twist in it every time he furled it. I think I remember reading here from some others with a similar problem.
We took the sail out and pulled the mast. The pieces were bottomed out against each other and there was a “knock” when the mast was held in both hands and given a good shake.
The masts on the AI and TI are joined with what is known as a “spigot ferrule.” Although somewhat ancient in terms of modern integral ferrules, it serves this particular purpose on this particular application perfectly well. However, spigot ferrules are designed so that the pieces should come tight before they bottom out against each other. If they bottom out before coming tight, the required taper friction between the parts will not be sufficient to keep the mating parts from easily slipping on each other. The pieces should come tight before bottoming out, which allows the mating tapers to obtain the maximum amount of contact with each other and allows for future wear.
Once I assured him that I had a “little” bit of knowledge on the subject, we took the female mast section inside and removed about 3/16th inch from the end with a stationary disk sander. Re-joining the parts the spigot can now move further into the female section and the pieces come tight before bottoming out. The result is that his mast pieces will no longer spin or turn on each other.
One last thing - When joining the sections, note the downhaul attachment on the furling drum and the slot on the top of the mast. misalign them by 90 degrees and bring them together. When they begin to come tight, twist them into alignment with some force. This is the proper procedure for joining glass and carbon ferrules of any sort. It locks the pieces in place (provided they are properly fitted to begin with).
While I’m not sure this is overly critical on a sailboat mast, it will indeed stop the pieces from slipping on each other. My friend appeared pleased, and relieved.