Here's a link to the book on the publisher's site.
Sterling Publishing: Catalog
It doesn't seem to have anything in the way of "new in this edition".
On Amazon though the product description for the 66th edition includes the following:
- Most up-to-date Federal laws, regulations, and fees
- The latest developments in outboard motors and inboard vectored thrust propulsion systems, including joystick controls - New mayday procedures
- Cutting edge technology: VHF/DSC radio; Rescue 21 coastal communication system; networking electronic devices; features and capabilities of GPS, radar, depth sounder, fish finders, and chartplotters; eLoran system; autopilot; NMEA 2000 and more
- Latest United States Power Squadron updates
- Expanded contact information for governmental and commercial organizations"