Perhaps what you are missing in the harness line length vs boom height equation is the simple fact that if you set your line length and boom height so you can hook in while standing up near the mast, the lines will be too long and the boom will be too low when you move back on your board to get into the footstraps.
So, if you aren't already in them, work on getting solidly and easily into the footstraps, then set your boom height and line length so your arms are fully extended when you are leaned fully back and supported by the rig.
This is one reason why many racers use adjustable length harness lines.
If you race Formula, you will find that you need a different line length for upwnd vs deep downwind as your stance will be very different on each course.
Maybe try a set of good adjustable harness lines, so you can make adjustments out on the water to get your setup really comfortable.
Oh, and the biggest issue sailors at your level face is getting a really good balance on the harness lines.
PG has it right.
Get your lines balanced to the point that you can take both hands off the boom for a few seconds and have your rig simply stay in position (not falling forward or back) and at the same sheeting angle (doesn't sheet in or out) giving you reliable and constant power.
Once your lines are truly balanced, it makes it far easier to learn to trust the rig to support your body weight.
And, that's the whole point behind harness lines.....to allow you to transfer most (if not all) of your weight off your feet and onto the rig through the harness lines.
It's a real paradigm shift when you go from having the sailor support the rig to having the rig support the sailor!
Hope this helps,
Last edited by Roger; 13th June 2009 at 06:17 AM.