I accepted the default suggestions for partitioning and an EFI boot was the result. If the HD has partitions on it to start with you need to use the “hold the command (alt) key down on powerup” procedure, and select the USB drive to boot. I created a “Startup Disk” memory stick from my existing Ubuntu Mate 16.04 host using the 18.04 386 iso image. The standard install worked with no tweaking. If you “Try Ubuntu” first, you can use GParted to remove any existing partitions. The important thing to do is to make sure the hard disk has no partitions on it to start with. I ended up using the 386 version and it worked well. I tried installing the 64-bit version, but it kept glitching when formatting the disk.
I’m reporting on my recent installation of 18.04 on two Apple Macs.
