The HF radio isn't difficult - you can buy or rent. The more difficult part is the aerial installation. There are some rogues around who will sell you a radio and install it (at a price!) but you'll find when you get out over the ocean that you can't raise ay ground stations.
I examined such an installation some years ago - nice radio, nice kit, installed totally wrongly and never going to work over more than a few miles.
Talk to an established ferry company who have done it aplenty, and ask who they use.
As said, there are routes where you don't need HF.