One of the best tools for doing storm at sea is the tri-recs rulers and you would
rotary cut. Storm at sea requires a 57 degree? triangle and half-rectangular squares. These are hard to piece unless you use use a template that tells you where to slice the point off the triangles. If you slice the point off the triangles, it's pretty easy to know where to line up the pieces for piecing.
Many manufacturers make tri-recs tools, including the 57? degree triangle and the half-rectangle. Marti Michell is one. I think I got the EZ International ones, that are frequently 50% off at Joann's .
http://www.joann.com/wrights-ez-tri-...r/4192068.html.
Some people think the tri-rec rec ruler is just a badly inaccurate 60 degree triangle. Nope. It is deliberately cut at the angle it is just for storm at sea (and certain star blocks that also use such an angle)