Start at the stern (back) of your boat and measure a spot 10′ up on your side rail. Mark this spot with a sharpie or if you don’t want to mark the side rail, put a small piece of duct tape.
Put the bait in the water with your rod tip touching the stern. Open your bail as you move your rod tip to touch the 10′ mark. You now have 10′ of line out. Stop the line from coming out and move your rod tip back to the stern and repeat as necessary until you have the desired amount of line out.
This is a simple thing to do in practice, maybe not as easy to type out. Hopefully this makes sense!! I do this all the time when we go to Canada and need to limit the number of rods and reels making the trip.