Probably an over estimation of the power needed. Some good info here from an owner https://youtu.be/1u267wy-d5A  more on the topic https://youtu.be/OW8mzN-KPN4 and

 http://www.electricsailboats.com also look at this gun boat install http://www.moonwave-systems.com/ and http://www.moonwave-systems.com/ . Both of these installs are high dollar, but something to aspire to.

I also see Rare Bird installed twin Torqeedo Cruise 4. (2.2K) 9.9 HP  Excerpt from the article on install (http://thetorqeedoshop.com.au/c4-harryproa/ ) suggests that much smaller motors would do the job.  “And we see here that 1000 watts on each motor brings her to 3.7 knots and this was before the trim was adjusted. And so I’m guessing it might take around 1500 watts total to run at 4 knots when she’s clean and well-trimmed.”

It would be nice to see more info on Cruiser 60 estimates on weight, sail area, payload.