As you can guess from the title, the tendon has snapped on the mast of my 300cs so it's a SUP right now. Is there a way to retro fit a different base to the board without hacking it?
Being a fixed hole in the board. I thought of some sort of plug that could be threaded.
Any thoughts?

Believe it or not, I have been retrofitting Normal Boge hourglass joints to Hifly bases since the eighties, takes a bit of engineering but keeps you guys on the water. You need to post them to me on the Gold Coast and average price is $150...good as new

lotsa people are doin it i.e. retrofitting the mast base

www.google.com/search?q=hifly+300cs+mast+base&tbm=isch&source=iu&ictx=1&fir=0m7iAzxNlFmZeM%253A%252C7C8nG_TYn2ChjM%252C_&usg=AI4_-kSHxkw8XG78ZKvSGTHmiAjLWwAZug&sa=X&ved=2ahUKEwiiruPKq_zfAhVsneAKHb-HBSEQ9QEwAHoECAMQBA#imgrc=0m7iAzxNlFmZeM:

on the other hand, once when a mast base broke on an old board, i analyzed the board condition and tossed all
it was a BIC SAMBA (or Calypso)