*** UPDATE: 08/29/2020 ***
Refer to this post on this thread for an updated step-by-step instructions on how to utilize the native boot from SSD that has been added to the Raspbery Pi 4: https://forum.openmarine.net/showthread....1#pid15791 This method has been tested on the above date and does not break the Moitessier HAT firmware.
*** UPDATE: 08/29/2020 ***
First. I'm new here. I searched to see if anyone else has done it, and didn't find much, so since I got it working, I decided to post. I tried a few methods and the one that worked for me is found here:
Raspberry Pi 4 USB Boot Config Guide for SSD / Flash Drives
I had a 64gb SSD out of an old laptop so all I needed was a USB cable. I purchased the recommended StarTech 2.5" SATA to USB 3.0 Adapter from Amazon and followed the outlined steps almost exactly. I already had my SSD drive prepared with a new partition, fresh format, and new install of OpenPlotter, so I saw no need to go though those steps again. After reinstalling my USB Wifi adapter, installing the drivers, and downloading the charts, OpenCPN is running much better.
I wish I could have this setup on my boat.
This shows the two volumes, one is the micro SD card in the Pi, and the other is the USB SSD.
I hope this is useful to someone here. I'm quite satisfied, myself, since at the start, I knew nothing about Raspberry Pi or OpenPlotter. At the beginning of the month, I'm going to try and purchase a Moitessier HAT and experiment with that. Unfortunately, it looks like they are not shipping because of this virus. I cannot decide if I want to go headless, or with a touch screen. My preference would be with the screen, but I cannot seem to find a good waterproof touchscreen option.