Seems like all the 1/4" oak I've seen at Lowe's and Depot are advertised as interior plywood. If there is a manufacturer's label you could get on the 'net and maybe get better info than you see in the store. Also, it seems like the oak I've seen at the "big box stores" has had very thin face veneers, which get messed up pretty easily when sanding - if you use it, look out for that.
Butt splices - what sort of boat are you building? On my Uncle John's Pirogue, the center frame landed right on the splice (I planned it that way, which is easy to do), so the splice doesn't show on the inside. As to the outside, I painted it. Figured it would tend to get beat up anyhow, so I went for simple and durable. So in my case, the splice is completely hidden. On other boats, it might be a different situation.
George
