It depends if the hike is ON the coast or ALONG the coast. My longest coastal hike was California Lost Coast, about 65 miles, 8 days. The first 25 miles is walking on the beach; the rest on a very poorly maintained trail with lots of 1000 foot ups and downs.

Not sure if any of this applies:

1) I really needed tide tables because there were points that were under water at high tide.

2) Camping was limited by need of a fresh water stream, and these were unevenly spaced along the route.

3) Between lots of rain and heavy dew on a trail overgrown with vegetation, I was constantly wet or damp. As long as you keep moving, it is fine. Aim to stay warm, not necessarily dry. Often I would simply go naked under my rain clothes. There was a constant wind so I needed an outer wind layer. If chilly I had one light weight wool layer. Sailors have used wool for ages because it retains warmth when wet.

4) Shoes will be wet all the time. Waterproof shoes will eventually get wet. Better to have quick drying shoes like trail runners.

5) I have observed that Japanese tourists who come here always have an umbrella. I actually have a 7oz folding backpack umbrella made in Japan!

6) Keep insulating and sleeping clothes in a waterproof dry-bag.

7) Either use a synthetic sleeping bag or a down bag that has the treated down that makes it water resistant.

8) We have ticks and all sorts of creepy crawly insects. I have to check for ticks every evening, and be sure you have an insect proof tent.

Your route may be entirely different. Try to get some local information on the route before you start. See what the locals use for equipment. I suspect your route is a lot more civilized than the Lost Coast.