Is it possible to join two carbon tubes to make up the 110cm mast length? I think I might use a piece of carbon rod or some brass rode to use for the pin. A hardwood pin is also possible. The join would be at about the 80cm mark.
Yes - but be sure the “pin” is long enought to provide a stiffer mast section over a wider length of the mast. I would also suggest buying/using carbon, as wood will need epoxy to prevent water and swelling - and breaking the mast tube. Any time you join tubes you add more strength/stiffness to a specific area of the mast where the joint takes place. This will change the ben characteristics of the mast in that area - so be sure to plan for this if cutting a mainsail luff curve.
May want to glue one end, an leave other a “slip fit” so you can take apart for travel/storage. All the kite shops sell inserts for the tube sizes they sell.
You can do it, but wont get a smooth mast bend. It will have a kink where the joiner is located. For the cost of a tube, why not just get another one and use the 80cm one as a B or C rig?
Being reliant on public transport, I found the RG65 a boon as it all fits in a sports bag except the mast. So … the mast had to be two piece. The mast is 6 mm x 1mm carbon tube with a 4 mm carbon rod spigot. It didn’t “look” that reliable, so the joint was sleeved with a 1" length of 8 mm carbon tube, which also provides a firm seat for the spreader. No problems yet.
Since all the carbon tube I have dealt with seems to be made with lengthwise fibers it has very lttle expansive(for lack of a better word) strength. It will split very easily. I always pulled a thread off the edge of some CF cloth and wrapped it around the ends of the tube. a little CA holds it well. Something else I have found the works well for this(as well as other wrapping) is Kevlar thread. It is very fine and very strong. It’s used for tieing flies. It is available in black.
Don