I'd never before thought about when windows in built into a ship stopped being square and became round portholes, or when the 15th century rudder was replaced by the captain's wheel, but I needed to know to be as accurate as I could about my ship in A Captain and A Rogue.
I found a list of ships contracted by the East India Company in the time frame, and mentally chose a small one to base my Ascalon on. I decided on a 432 ton (water displacement area), two-masted ship with a crew of only 32 men. It needed to be small to be able to take an unscheduled trip to an island, especially if the boat was to be sailing in an area which might be more like an obstacle coarse than a sea. I tried not to mention specifics, knowing many photos and drawings show 3 masted ships..
Even naming the ship wasn't as easy as I expected, I named it Goldenrod first and then I thought about the plant. I didn't even know if that would have been the name of a plant an Englishman would have known, or named his ship for in the early 1800's. I think it would have worked, but before I researched that, I changed the name to that of a legendary sword and moved forward.
In researching, I walked on a replica of a pre-1500's ship. It carried scent of a pine forest because it had been coated with the pine waterproofing material of the day.
It was more soundproof than I expected because of the thick plank sides.
It was also more combustible. You have lit lamps with breakable glass on a bobbing object coated in a flammable rosin, and the water to put out the fire is a wooden wall away from you. I believe Alexander Hamilton, the face on the USA ten dollar bill, was once on a ship which caught fire. A fairly slight man, he was lowered over the side to bring up water for fire fighting.
Even on the replica, the lanterns were secured to keep them from excessive movement.
After stepping on board one sailing vessel, I wanted to tour many more.
Starting the research was a struggle, but so was ending. I could have happily immersed myself in another bout of study--just not on ships away from port. I don't swim.