Ha, ha, ha... 3 guy, 200 pounds plus?

Get a freighter canoe!
http://www.islandnet.com/~canoes/20ft_freighter.htm But you won't be
able to carry it yourself and they are pricey, even used.

A loaded canoe does not have much freeboard, at least not with the
Frontiersman canoe I had.

You might want to look and this site and learn a bit more about this:
http://www.redrockstore.com/canoecompare.html

For 600+ pounds of weight, you could have serious problems in a smaller
canoe. We sunk ours at the lake, doing a silly trip with our 2 dogs,
all our camping and hiking gear and the two of us. I guess we were
close to 650 pounds loaded. All it took was the dog (a large German
Shepherd) to jump to one side and over the water came into the canoe
and down we went.

You might be better off with a Zodiac or some other lightweight
inflatable. Just my opinion.

Or, as an alternative, you might want to look at sea kayaks. I'm not
big on either kayaks or canoes, but I do like the sit on top kayaks for
summer use. They are great for snorkeling, lake, or river travel.