You left out the most important information:I left the boat the other day, and it was pretty windy-- blowing about 15-20mph. I have a spring line on each side, and two bow and two stern lines on my boat, but they are not tied all that tightly to the dock so the boat kind of floats around maybe 6" from side to side with the wind.
I looked around at some other boats on my dock and some of them have the lines tied very tightly to allow no slack or boat movement. Is there a correct way to do this to reduce chafe and stress to the lines? I'm on a floating dock.
Are you tied to a floating dock or a fixed dock? Are you in a location where tides (or the wind) raises and lowers the water level? Are there wakes and waves or is it a calm, protected location?
You can tie up pretty tightly to a floating dock. but not to a fixed dock if the water level fluctuates or there are waves or wakes. You have to allow for the lowest and highest expected water levels. In some cases, you have to use extra lines to make sure the boat doesn't end up under the fixed dock at low tide and get trapped there as the tide rises.
Look at how your slip neighbors secure their boats and talk to them. Figure out which ones are the smartest and most experienced and secure your boat the way they do.