Here is a link for a free pattern and it includes some templates. There are several free Storm at Sea quilt sites available to look at. Also search this board as there are a couple of Storm at Sea quilts posted. Maybe those members posted if they used a certain ruler set that made the project easier for them.
Good luck with your project.
http://www.fonsandporter.com/article..._quilt_pattern
Here Quilt in A Day talks about rulers for the block.
http://www.quiltinaday.com/imgs/face...AtSea_feb6.pdf
Free templates
http://oldsite.mccallsquilting.com/q...e_diagrams.pdf