Assuming you mean x to stand for the distance between the ending of the direct line to shore (where you have the "2 Miles" line meet the horizontal line, above) and the point where the boat actually landed, then the Pythagorean Theorem (or the Distance Formula) should give you the following "distance" expressions:

. . .boat:

. . . . .sqrt[2^2 + x^2] = sqrt[4 + x^2]

. . .land:

. . . . .sqrt[(4 - x)^2 + 1^2] = sqrt[17 - 8x + x^2]

Since d = rt, then t = d/r, so the "time" expressions will be:

. . . . .boat: (sqrt[4 + x^2])/2

. . . . .land: (sqrt[17 - 8x + x^2])/4

Add the expressions for the two partial times to get an expression for the total time.