Didn't BlowinSouth just buy a T30? He's probably up to date on the pluses and minuses.
Was it a T30? I missed that, I guess.
Just as a follow-up to my earlier post, please don't take offense. Just kidding around a bit.
However, it does strain credulity that any production 30 footer could hit 20 knots, so some of us are certainly intrigued by this mystery. The most obvious explanation is that your GPS receiver is malfunctioning, or you are somehow misreading the information it is displaying. I'm not trying to insult your seamanship, and to prove it I'll mention an embarrassing story of my own.
I was once crossing Chesapeake Bay in some really nasty weather with one of my brothers and my father. After a fast beam reach across the Bay, we had to head up as we rounded a bell buoy waypoint for a long beat to weather. It was blowing and raining sideways, miserable conditions.
After hardening up, reefing down, and getting sails trimmed, we took stock of our progress. We were dismayed to learn that our VMG was only 1.8 knots on the GPS. I then did everything I knew of to improve the boat's sail trim, including adjusting leads, reefing the genny to reduce heal, tweaking lines everywhere, etc etc. As I made these adjustments, my brother called out our slightly improved boat speed "1.9 -- 2.0 -- 2.1 -- 2.2" The boat felt fast to me, but the GPS was saying otherwise. Imagine my frustration and concern, knowing that we had a 10 mile beat to weather and it was already late-afternoon on a late autumn day, with miserable conditions.
Finally, as my brother continued to call out our ever-so-slightly increasing speed, it dawned on me. I went back to the GPS display and discovered that it was showing the steadily increasing distance from the previous waypoint we had rounded, not boatspeed!!!
Our actual VMG was well over 6 knots!!
Moral of the story: Sometimes we misread the information being presented.