[TheForge] Permalac over urethane ?

[Peter Fels & Phoebe Palmer]

Howdy all:
Can  i get away with using Permalac over water cleanup 
type urethane spar varnish?
I've sprayed on 5 coats of the urethane on a steel 
sculpture with a complex surface configuration .
It simply doesn't have anywhere near the necessary film 
strength. Seems brittle and flakes off under light 
fingernail scraping.
Not at all what i expected from spar varnish.
I mightily do not want to refinish this stinker, having 
spent way too much time on it.
Any solutions please...be appreciated.  pf