These should be tight with your mast rake at 31'10".
Tightening the turnbuckles by hand as tight as you can should produce close to the correct tension.
Be sure not to over tighten the sidestays. The sidestays need to be equal length.
Hoisting a steel tape with the halyard. Lock it in place and check each side stay.
Measure your sidestays with firm forward pressure on the mast and firm tension on the side stay to the deck of the boat on both sides.
A good rule of thumb is that your sidestays should be tight in medium winds with your normal mast rake setup.