Can ships from Dalian to Yantai pass in winter? Is it safe?

It has nothing to do with the season. The key is to see whether the wind is strong or not. If the wind is strong, the ship will sway badly, and people who are not used to sailing will get seasick. In normal weather, you can't feel the hull shaking. Ships from Dalian to Yantai are all ro-ro ships (much larger than passenger ships), with large hulls and deep water, which are difficult to shake in general. If it's a typhoon or something, it will stop. But so far I haven't seen one turned off. When you travel in winter, it is definitely much safer to take a boat than to drive.