If the easy out hasn't worked, another thing I have seen in workshops but never used is a spray that freezes the bolt, it's used to extract bolts from engines. The theory is you spray the bolt and the contraction cracks it away from the thread


Jeff Southall
Current boats
Nacra 5.8 1703 Animal Scanning Services
Nacra 5.8 1667 Ram Raider
Nacra 18 Square
Arrow 1576