Not sure if this is the same as shown on the TV show, but here is how we do the CompTips using a mandrel.

The mandrel is actually undersized and easily pulls out of the finished tube.

The mandrel has an air tube running its length, the mandrel is perforated. We cover the mandrel in a plastic bag. We apply (wrap) the cloths and resin to the mandrel on a large table.

There is a two part mold that is shaped to the outer contours of the mast. We coat the mold with black resin putty.

We place the glass wrapped mandrel in one of the mold halves, then close the mold halves together and clamp.

The molds are heated and air is forced into the mandrel. This expands the bag inside the wrapped glass and forces the materials out to the contoured mold surfaces.

Once the part is cured, we open the mold, remove the part with the mandrel still inside. Then we slide the mandrel out from the bottom.

Most glass masts would be tapered, so the mandrel could be the actual mast inner shape. The removal would be them same... from the open bottom.

By the way... if you want to see how we make some kayaks, look for the "Made in America" (on the travel channel) segment about Hobie coming after the first of the year. They filmed the segment last summer here in the Oceanside plant.