I am a big advocate of boards instead of keels on multihulls. I understand the preponderance of production multihulls have keels. And boards can mess up the interior. The big deal, I think, is the greater lift that a board generates. When I got new computer a while ago, I had not gotten around to downloading Dave Vacanti’s Loft 97 foil creating program again. He has a free demo of it. I urge you to compare keels to boards on your own.
Keep in mind that nothing else will push you windward except lift.
See http://vacantisw.com/ Go to the free downloads.
For example lets compare 16 square foot foils. Same foil family, NACA 00. For simplicity, no sweep.
Assume a board with 2′ chord and 8′ draft. At 5 knots the board generates 800 lbs of lift. At 20 knots, 12,000 lbs of lift.
Next, a keel of 2′ draft and 8′ chord creates 120 lbs of lift at 5 knots, and 2,400 lbs at 20 knots.
Now look at a common 1′ deep keel. At 5 knots, 35 lbs of lift. At 20 knots, a mere 550 lbs of lift. People. Again, nothing else will push you to windward except lift.
And as I tell my catamaran customers with keels, take a cell phone with a marine towing service on the speed-dial. If they run aground, a mono can kedge off of the mast and get free. A trimaran can chase everybody onto the ama and get free. If the tide is going out, a cat with keels will spend the next several hours there. Period.
Finally, if you stuff it up on a rock, with a keel you must haulout to fix. With a board you can keep sailing as you repair the board.