On Thu, 23 Jul 2009 16:51:43 -0500, "mr.b" wrote:

I'm looking for tuning hints here. It's just a conventional masthead rig
with single lower shrouds and no backstay tensioner installed. Headsails
are hank-on. Main has 3 full battens.

If the rig tuning is off it should show up as a difference in sail
shape. Does the main seem fuller or flatter from one tack to the
other? How about head stay sag? Are the jib leads in exactly the
same position? Have you tried adjusting them separately? Is the jib
luff the same distance off the spreaders on both tacks?

Many paddle wheel knot meters read differently on opposite tacks.
When I was working with high tech instrumentation on my old Cal-34 we
ended up installing port and starboard paddle wheels with a switch box
which I had to remember when tacking. It sounds like your boat is
actually handling differently however, not just a speed difference.
If all else fails try to get an experienced rigger and/or sailmaker to
go out with you.