Does having hand sketches in a book about engineering and construction look amateur and bad work or they might be ok and look even original, as they are done directly by the author's hand, as long as they are drawn well and informative? What do you think? There will be a lot of them, but they are mostly simple sketches that can be drawn in under 10 minutes each, by hand.
I think it depends on the quality. I work with a lot of engineering drawings—some hand-drawn work by a draftsman looks as professional as anything done using a computer. If they’re high-quality I don’t see why it would be a problem.
Are they meant to be hand sketches within the context of a story? As in a character actively drawing in a scene?
Not at all. I am an engineer only explaining concepts about engineering, construction, structures etc.... sketches are just to explain better, easier.
Okay. You should be fine so long as the quality of the drawing accurately represents what it purports to be. Whether including drawings elevates the story or not is a different issue.
in a trad deal the chances are high the publisher will recommission an illustrator if necessary if you are self publishing be aware the the more illustrations you put in the higher the file size will be and thus the more you'll get charged for delivery on KDP etc
As well as the overall cost of a physical book because they will have to use better paper which costs you more.
