Your mistake is using Journal Entries. Journal entries can only be used to adjust accounts.  Inventory is not an account, they are items in your inventory.  For inexpensive items you use a lot of, say screws, you don't have to track them as inventory. You can set up a COGS account and call it "Job Materials."  I don't actually see why you need to keep an inventory if you build so few boats. If you buy everything as needed for each job, set up a job or a "Class" for each project and keep track of your expenses by Class. There are some good online tutorials on using Classes.  Great thing, too, about "Classes" is you can run a P&L by Class.

I don't know what state you are in, but some states tax companies on their inventory. Something to consider...