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Kit Guide

Fitting Upper Mast Bungs to a Topper

By Dave Cockerill 2nd October 2020

Upper Mast Bung_New

Have you got a leaky Upper Mast?

Topper upper masts are designed to be sealed floatation chambers that slow down a complete inversion in the event of a capsize. They work ok when empty but really make things difficult when they are full of water! Apart from speeding up the inevitable full inversion, they increase the likelihood of a capsize by weighing the rig down and they make the boat pitch badly in any waves at all. There are two seals/bungs, one inside the bottom of the upper mast and one underneath the masthead crane at the top of the upper mast. The Cause? The ‘bungs’ are a push fit and generally work fine but once disturbed they need re-seating. Pushing the burgee in too far will cause the bung to either puncture or to be twisted. The Cure? See diagrams below:
  • Remove the masthead crane by drilling out the rivet and carefully driving it out (a gentle tap on the front and then the back repeatedly is the best way).
  • Drive the old bung sideways and either hook it out or leave it twisted but driven further in.
  • Remove any corrosion or dirt from the inside of the mast tube.
  • Drive the replacement bung in, being sure to keep it square, with a wooden stake of the right diameter (ish!). There is a lip on the bung, which does the sealing – it will go! Use a little lubricant if necessary; washing-up liquid is good. Some people use a sealant as well, but I have not found this necessary.
  • Do the same to the lower bung.
  • Replace the crane

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