ボクに任せたんだ。君たちは大船に乗ったつもりでいるといい。
I'm taking care of it. You can relax. You can rely on me.

大船に乗った気がする。
I feel as I can rely on things now.

大船に乗った気持ちがする。
I feel as if I were aboard a great ship.

もう大丈夫。大船に乗った気で心配しないで。
It's OK now. Don't worry. You can depend on me one hundred percent.