Range Ruler

What I want to do is use the LOS as a range ruler by having it set to a set distance when drawing the LOS from a counter.
As an example…

A ship has a short range cannon with a distance of 1 " and a long range cannon with a distance of 1.5". One cannon is located near the stern of the ship and the other near the bow of the ship. I would like to see if the short range cannon (located near the stern) can fire at another ship nearby (the enemy ship is off angle and closer to my firing ships bow). This would be easy to determine by simply drawing a LOS from the firing cannon to the enemy ship using a LOS with a pre-determined length.