Grain orientation is critical. In addition to using vertical grain stock, you need stock with minimal runout. The grain should be nearly straight and contiuous from one end of a rib to the other. I made the mistake of only concentrating on one aspect of the grain on my first boat and learned the hard way.

BTW, I haven't found any benefit to soaking. Even when soaked for several days, if you cut off the end of a piece of stock, you'll discover that water has only penetrated a few thousandths of an inch into the wood. The big downside to soaking (other than the time it takes) is that it make the wood swell. Your ribs won't fit their mortises unless you thin them, then they'll be loose after they dry.