Since I posted the detailed pictures of the planks below, the general consensus across the forums is that yes, the lighter wood is indeed sapwood. The holes gave it away. It's excellent for indoor furniture, worse than useless for boats.
Apparently it soaks up liquids, including whatever you might use to try to seal the ends of it, and then it soaks up some more.
Since being a rank beginner when it comes to working with oak, I will need to practice various cuts and joints. So I guess the sapwood won't go to waste. If I have Lots left, I may use if for the slats for the seats, then when it rots away, I'll just replace it.