Confused on Fitting tool for skiff - EHP drops when actually fit

I’m returning after 5 years and I wasn’t an experienced player even then (but I kept the training going because I kept forgetting to cancel).
Setting up Skiffand when I simulate a fitting I see an EHP of ~54K but when I actually fit the ship it drops into the 40’s. I’m guessing it’s me not understanding the fitting tool, but if anyone could help me understand what’s going on I’d appreciate it.

Activate simulation with fitted ship. Hardeners and so.

Thanks. That fixed it.