She would never notice that hanging off the back of the boat
Every husband makes one stupid mistake...I bought a new camera and didn't tell my wife.
She found out when a friend asked her how I was enjoying my new camera at a dinner she was at.
It would have been easier to remember to tell her I bought the camera than to forget to tell her. It is now a running joke in our marriage, well I don't think it is that funny, but she can make me squirm (to her delight) when she mentions the camera.
The boat build costs are tallied on her spreadsheet and she is well versed on every cost.