Re: understand 12v electrical
I'd suspect the monitor and it's set up. I'm assuming you set the capacity to 232ah.
After the initial install did you allow it to 'sit' and learn your batteries without a charge as the manual undoubtedly says you should?
When it was showing a state of charge of 85 % what was it showing as AH remaining?
You may need to just unplug it and start from scratch, but be assured your 60w of panels and a mppt will and should bring it up to full charge and keep it there if the boat is used as a weekend cruiser and you don't moor the boat with under 60%.
Lessons learned are opportunities earned.