The way it came to me was as David and I were driving along the beach road talking about all the extraordinary events we have experienced together and the wonderful people we have met along the way. At almost the same time, it hit both of us that none of that began until we were willing to "step out of our comfort zone" and leave Rome where we knew so many people and were well known, trusting that God was indeed leading us to do that.
We drove on for several minutes pondering what we had just realized. The ferry came to my mind's eye and I described it to him. Later as I was talking with one of our pastors about this epiphany, he pointed out that the part of the ship under water is that which causes it to float and to move. He suggested I bring it up at house church, which I did.
One of our members is a lifelong sailor (as in sailing ships). He pointed out that not only does flotation and mobility come from below the waterline but so does stability in storms (because that's where the ballast is). So, as we have shared this with prayer partners (remember the part about "withstands the scrutiny of other prayerful Christians" as being a part of testing decisionmaking for God's Will as contrasted with our own), more of the meaning has been revealed.