Home Fly fishers shape the world of fly fishing with their stories, journeys, and friendships. This website is our shared journey of science and research applied to fly fishing. We hope our explorations and insights will contribute to your fly fishing enjoyment -- and to your stories and friendships. Our current research projects: Are long casts overrated when swinging for steelhead? We think so! Shape and depth of fly lines with sink tips under various water velocities Sink rates of fly lines based on simple measurements you can make yourself Fact-based fish weights and steelhead weights based on length and girth Spey casting methods that make casting a breeze Spey casting methods for distance -- with an in-depth analysis of tournament casting, including photo sequences and videos Good setups for Spey casting sink tips under various conditions What's new: Spey-O-Rama, World Champtionship of Spey Casting, tournament competitors and results Bob Pauli's unique and thoughtful perspectives on fly fishing, two-handed rods, and a wide range of other topics in an interview with the California Fly Fisher. Bob Pauli's updated spey casting instruction booklet -- Fresh, accurate, and readable introduction to spey casting. Free download, English and Spanish editions. Steelhead weight formula -- now based on meticulous measurements of 115 steelhead, both bucks and hens from many different Pacific Northwest rivers.  Includes information about formula accuracy and sources of variation by individual, by gender, and by river.  Includes explanation of our original formula (weight = length * girth2 / 690) and an improved formula which adjusts for the systematic differences in girth taper associated with fat and thin fish. River reference card -- Key results from this website summarized in a small card for ready reference on the river. Sink tip research center Find out how your favorite sink tips perform under water -- based on measurements of your fly lines you can make yourself. Reduce and simply the number of sink tips you carry on the river. Do your own analysis of your favorite sink tips with rule number look up tables, sink rate lookup tables, do-it-yourself sink rate and rule number calculators, and a sink tip converter that allows you to convert multiple sink tips into equivalent lengths of a standard sink tip of your choosing. It turns out that the current industry standard method of determining sink rate overestimates actual sink rate of lines you use for fishing.  We explain why.  As an alternative, we offer a sound scientific approach for determining sink rate for a range of water temperatures in fresh and salt water, and easy ways to put it to use with our lookup tables and on-line calculators. Our article on estimating fish weight is now available in the May 2008 issue of Fly Fisherman Magazine. Click here for the fish-weight look-up table referenced in the article or simply use our on-line fish weight calculator. Our article, "Ruling Your Fly Depth," (Fly Fisherman Magazine, December 2007) is now available as a free download. Based your requests, we have completed an in-depth analysis of spey casting techniques for distance -- illustrated by tournament casting videos of Gordon Armstrong -- one of the world's finest long-distance spey casters. Based on your requests, we have completed an in-depth comparison of several tapered sink tips, including VersiLeaders (Rio) and PolyLeaders (Airflo). We have extensively updated the "Fly Depth" portion of this website with information on rule numbers, fly depth results (including a graph with the same information as in the article), fly depth formula, sink tip length formula, and estimating water velocity. Check it all out! We encourage others with fly fishing insights or questions consistent with our research-based mission to let us know by e-mail.