I assume you mean a 90* turn.
If we have 3 sides of a right triangle, they are related to eachother by the Pythagorean theorem.
Replace with known values of A and B
Simplify and solve for C
11^2 = 121
8^2 = 64
121 + 64 = C^2
The ship is approximately 13.6 miles from its starting point
Hope this helps
:D
- Jeron