There’s a cliche in writers education to ‘write what you know’, which has always seemed a spur to know more and then write about it. Research is not a luxury. Some (famous, male) author I head on the radio a long time ago was describing his use of a house he walked past everyday. The first-floor bay window gave over Hampstead Heath. “And because I’m a proper writer,” he said assertively, “I did my research. I knocked on the door and asked to look out of that window to check.”
Writing speculative or historical fiction allows a bottomless pit of investigation. Just how did ordinary seamen get their prize money in the first decade of the 19th century? Does a squid manoeuvre by straight jets of water or by generating mini-vortices? It’s all fascinating and it’s a great distraction from putting new words on paper or screen.
Of course, you want to use it all. When I am intimidated by what I don’t know, learn a little of the vast knowledge out there from specialists, and then want to use every scrap of it, I turn to the wonderful interview Ernest Hemingway gave to the Paris Review of books, the whole of which is on-line here. He says
I always try to write on the principle of the iceberg. There is seven-eighths of it underwater for every part that shows. Anything you know you can eliminate and it only strengthens your iceberg. It is the part that doesn’t show. If a writer omits something because he does not know it then there is a hole in the story … I’ve seen the marlin mate and know about that. So I leave that out … But the knowledge is what makes the underwater part of the iceberg.