Smoothing lines from scanned image saved as pdf

Hi, I am trying to laser cut some parts for a model boat. I scanned the relevant section of the plan and saved it as a PDF file. I imported into Lightburn and used the trace tool but everything comes out as double lines and it is impossible to get a smooth cut, likewise with the engrave part. In the example, I want to engrave the deck planking, then cut out the perimeter. I did delete all the superflous information.