From my research i found out that what seemed to be the best method to ensure that there would be no seperation / slippage was as follows.
1) rough the painted surface up with 80 grit sandpaper, and rough up any bare aluminum with same
2) blow off dust, then wipe down all surfaces with Xylene
3) spray self etching primer on the bare aluminum spots.
4) after everything drys wipe down boat again with xylene, then start coating with durabak. Left it overnight for first coat to dry and then did second coat today.
People that have followed that procedure report no slippage / seperation... hope thats the case for me.
