This is another one of those calculators, this one to compare boats.

http://www.image-ination.com/sailcalc.html

Can't vouch for any of these calculators. There are probably too many factors invoved for them to be accurate. The data on the Commander in this one is wrong too.

As far as displacement for our boats, I've seen many different figures. I don't know if any of them account for engine, fuel, water, beer, crew, stores, ice, more beer, etc.

Interesting note at the bottom about hull speed, stability, and being able to carry sail. That's one reason why we get to torture bigger boats.