Whatever drawing program you use there will be a fairly steep learning curve, especially if you're new to CAD or anything like it.
LibreCAD is another free 2D. But it's a bugger to learn.
Don't waste time on a drawing program that does not support layers. It's just too hard to work out ideas as you go along without fully starting over. File format can be important as well. At a minimum for CAD work .CAD and .DXF formats. More here
CAD file formats
If you need 3D visualization Sketchup is OK. I say just OK because it really doesn't work well with boaty shapes.