barne wrote:

On a W/L race, it makes sense to use VMG%. Polar% is only percentage of speed in the direction you're sailing so if you were sailing around at very wide wind angles, you could potentially have great polar% but in reality not doing too wall in your race.

When analysing, remember that your boatspeed is probably much more accurate than your wind angle. Good boatspeed calibration is a lot easier to get than wind angle calibration that differs every day and during each day. When I do analysis I keep an eye at target bsp % as well, even though it only tells the half true, it will at least give a more accurate output.

In my experience (especially in a one-design fleet or sailing with similar boats) the best approach on W/L races is to use the data to analyse and present HOW you sail the boat (fast/low or high/slow, more or less heeled than normal, more or less rudder than normal) and then cross-reference that to your percieved performance against your competition.

Can you clarify your issue in your 2nd section? Are you referring to tuning the numbers in the start box?

I placed a TWS and TWD hold in the Start menu.  I used the average TWS and TWD from the values derived in strip chart for the entire race.  In the course window I looked at the total time to sail the course.  I then adjusted down the Nav Polar % until the predicted elapsed time matched the actual time it took to sail the race.  I would guess that this method would be the most accurate way to compare theoretical VPP performance to actual performance on the race.  Calibration values would have no influence unless recorded TWS is incorrect.