Torqueedo... yawn.
I worked at West Marine and I think we sold one of these in 2 years. There simply is not the thrust for anything like a proper yacht of any decent size. The pic in the WM catalogue shows a '6-HP' Torqueedo on the back of a 3500-lb Alberg Kittiwake/Sea Sprite. I doubt this motor would push this boat at 2 knots for more than 10 minutes before it had killed a size-24 battery. The one with the attached battery, reputed to be worth about 2 HP, is even worse. Using Torqueedo's specs I once calculated that two people in a small dinghy or inflatable could cruise at about 2 kts for about half an hour on one... and that's not taking into account that it would slow down as the battery waned.
Seriously-- and all wishful thinking aside, please! --the Torqueedo as I became familiar with it is simply not a replacement for a gasoline-powered outboard motor of any respectable size for use on an actual yacht. For a canoe, for a pedal boat, for a small dory used on very protected waters (i.e., lakes with no current or wind issues), I'm sure it's fine. (I would be sure to take oars or paddles with me though.) For anywhere there might be chop or wind or weight, or for a trip of any duration, all common sense has got to conclude that it's out of the question.
And for eco-conscious people out there, remember that ALL electric power increases society's dependency on nuclear reactors, because that's where we're (still) getting most of our electricity from-- just something to consider.