Bob,
Excellent analysis on the sail shape. That was exactly what I did once we  
reached the dam. I dropped the pop top, lowered the boom and brought the genny  
sheets inside the shrouds. I sailed with a full main and about a 110 genny on  
the way back. I had great balance and good hull speed. Now, if it had been 80 
 degrees instead of forty, the rules would be totally different. Full main, 
upper  position, full genny and I'd be sitting on the rail. :)
 
Rummy