Although I do not have experience fixing masts, I do have a lot of experience with composites and repairs. If that comptip is carbon-fiber it is probably fixable judging by the look of the photo. However, it may not be fixable by you. Also, (although I can`t see any in the photo) if there are longitudinal breaks in the mast - cracks running up and down the mast, extending more than a few inches - it may be a real problem to fix and not safe. On the other hand, if all you have is a horizontal break, as the photo shows, you could attempt a fix as follows: (1) build a jig/support system that holds both broken halves in PERFECT alignment throughout the repair, and also lets you have some access to the break point. This can be done with carefully selected (straight and true)lumber built into a U-channel type box/trough. (2) You MUST be able to obtain a 3 foot piece of aluminum or steel tubing that fits perfectly snug within the diameter of the comptip. This piece must be strong enough to withstand the forces of a mast-like application "all by itself" - or very close to it. (3) Degrease/dewax the interior(especially) as well as exterior of the repair area. Acetone can be used over several applications, with clean cloths used for each application, but a commerial product from an auto body supplier would work best. Clean, Clean and clean again! Also perform this procedure with the aluminum/steel insert you will be using. (4) Coarsely and completely abraid the inside of the comptip(tricky but possible) and the insert. But only do this after the cleaning. (5) Using a low viscosity epoxy (I like west system) thinly coat the entire insert and contact area inside the comptip. (6)Then mix up a generous batch of medium viscosity epoxy with fumed silica or milled fiberglass (also west system) to the thickness of smooth peanut butter. Note: slow cure epoxies form better bonds that fast cure epoxies.(7) Now, here is the critical part. Being overly generous with the thick peanut-butter-type mixture, apply it to both the insert and inside the comptip (which are still wet or tacky with the thin epoxy) - taking exceptional care to make sure All GAPS between the repair insert and the inside wall of the comptip will be filled, join the two halves of the mast. Be careful to keep the insert centered on the break. Check and re-check the alignment because this is a "one shot" deal. However, avoid moving the repair halves as much as possible. Let it cure 24 hrs, then remove it from the jig and carefully grind off all excess epoxy. Taping around the comptip about 1/4 inch from the break (before the repair) will make this part much easier. Touch up with flat black paint. If you want extra support or confidence, some strategically placed rivets using stainless covering plates (similar in thickness to your mast tang) both above and below the repair may really help. These do not have to be big, just well-placed and tidy-looking. Just be sure the rivets are long enough to make it through the stainless plate/support, the comptip AND the repair insert too.
Good Luck,
