Flicka 20 Mast – Tang Removal
After lowering the mast on Sampaguita, my 1985 Flicka 20, disassembly was next. All was well until the shroud and stay tang assemblies. Even installed, I could see there was galvanic activity where the stainless steel tangs met the aluminum mast. Since the tangs share the same loads as the chainplates, and I would be removing and inspecting those, it made sense to do likewise with the tangs. The mast was 34 years old, and I suspected these assemblies had been together since then.
3/8″, stainless steel bolts with nylon, locking nuts, secured each tang assembly to the mast. These were removed with ease and looked great. However, the rest would not come apart with no obvious way to pry them.
The mast is a Kenyon spar and internet research turned up Rig-Rite as a vendor. Their website aided me in understanding the assemblies.
There was an aluminum compression tube spanning the inside of the mast. Inserted at each end of this tube, were stainless steel flange bushings that held the tangs. Finally, a stainless steel bolt held the assembly together.
I identified the stainless steel tangs as the “dog bone” type, which matched the shape. There was a commonly used flange bushing with these, which defined the size of the compression tube. The compression tube served three purposes. First, it prevented the mast from being squished from tightening the stainless steel bolt holding the tang assembly together. Second, it provided a large bearing surface for the assembly’s downward force on the mast wall. With aluminum on aluminum, this would mitigate galvanic corrosion on this high-stress area. Third, the stainless steel bushings fit snugly inside the tubing, holding the tangs and reducing the hole size. A lighter stainless steel bolt could then be used, reducing weight aloft.
After 34 years the stainless steel bushings, and the aluminum tube, dissimilar metals, had seized together. I came up with a plan, then called my local rigger to see what they thought. They were kind enough to spend five minutes talking it through, and they confirmed I was on the right track.
I heated the bushings on each side with a portable propane torch. I cycled through each one, three times, with 10 seconds of direct flame. Then, I sprayed Liquid Wrench on the assemblies and let them sit overnight.
I purchased a 6″ long, 1/4″ diameter, stainless steel bolt from my local hardware store. I inserted this through the bushing on one side of the assembly, into the compression tube. I placed it up against the inside edge of the bushing on the opposite side and gently tapped the bolt with a hammer. Checking that I wasn’t damaging the mast, I gradually increased the force. Eventually, it broke free of its bond, and I was able to tap the bushing out of the compression tube. With one bushing off, the rest of the assembly slid from the mast. In the end, I had to strike the bolt quite hard to break it free, but the compression tube did its job of protecting the spar. I repeated this procedure with the upper tang assembly, and it too came apart.
It was worth going the distance to inspect the state of both the assemblies and the mast. When I reassemble them, I will use new parts and add Tef-Gel, to inhibit corrosion and ease future repairs.