Catawba isn't actually an Island, - It's a peninsula that is out RT.53 east of Port Clinton about 8-10 miles.
Thats where Millers ferry runs from. I think it's the closest point of mainland to get to PIB.
If you go through Port Clinton and head east on RT.53, Sand Rd. veers off to the left (almost a Y in the road). There are a few nice marinas out that way, and some beautiful houses on the water, (intermixed with campers...). I haven't been out there in a few years, but when I was living up there used to run out there every few weeks. Several dealerships out that way and used to be a Merc store (may still be there?).