I just came across this program the other day. Can't say much about it as I only used it for about 3 minutes, but bookmarked it.
Draw your boat, van or off-grid 12 V system from a catalog of real parts — every cable and fuse sized against ABYC E-11 as you wire it. Free, no sign-up.
crimp.studio
Some folks are using MicroSoft Visio to draw circuits. I picked up a copy for about $10 from StackSocial.com
The drawing features in MS Word also work. Takes a bit to get the hang of it, but works for basic drawings.