Kiyoshi Nakagawa's research on the sink rates of Nymphs - Testing The Theories

By Rene Vaz (replicated courtesy of Fish and Game Magazine)

The obsession we refer to as fly fishing is different for so many people; for Kiyoshi Nakagawa that obsession couldn’t be any more extreme. Kiyoshi or Yoshi as he is known to friends is in the enviable position of having been able to turn his passion for fly fishing into a career. Not only is Yoshi a part owner of Auckland's new fly fishing retail store Rod and Reel but he also operates a successful guiding operation focusing primarily on Japanese clients and training up and coming competition anglers. What’s more, Yoshi has also made time to further his angling knowledge in a number of scientific studies focused on generating some concrete data towards some general day to day perceptions we all have as anglers. These projects, conducted along with Professors at the Japanese Kanazawa Institute of Technology, are of particular interest to all of us as anglers.

An avid fly fisher from the age of 15 Yoshi had read about fly fishing in New Zealand and at the age of 23 took the opportunity to move to New Zealand along with the 2003 Japanese America’s Cup Squad as a strategic researcher. During these early days in New Zealand Yoshi spent all of his spare time fishing around the North Island and in 2004, began competition fishing and working for then tackle retailer Tisdalls in Auckland’s CBD.

Yoshi’s competition fishing took him to the world championships in Slovakia in late 2004 representing the Japanese team and since this time Yoshi has had a number of placings for both  the New Zealand and Japanese teams. One of the highlights of his career was in 2008 when he represented his home country Japan on his new home waters around New Zealand where he finished a very respectable 18th in the world.

Yoshi has always shown a strong commitment to teaching up and coming fly fishers, whether at a truly elementary level ,or for those wishing to further their skills. As a result of his passion for teaching, in 2005 Yoshi and Peter Scott (his colleague from Tisdalls) started their own fly fishing academy. These activities have been continued over the past number of years and have continued into a new retail store concept ,Rod and Reel, which was opened for trading in October 2007 by Yoshi and Peter, along with new business partner Paul Dewar who’s had previous experience managing the New Zealand fly fishing team. One of the primary drivers of the Rod and Reel shop has been Yoshi’s ongoing energy and passion towards conducting fly tying and fishing lessons throughout the year from their Newmarket premises which has a purpose built teaching area onsite.

With a background in mechanical engineering from Kanazawa Technical College and further post graduate studies from the landing School of Boat Building and Design in the United States. Yoshi had always found that many of the concepts and beliefs he had been taught as a fly fisher were based primarily on assumption, versus the researched facts he had been brought up in during his academic training. As a result Yoshi, along with the assistance of his original professors have began to conduct a number of physical experiments on the performance of fly design on sink rates in varying environmental conditions. Yoshi’s current research project focuses around the sink rates of trout flies tied from different materials. Of particular interest are his findings on the vastly different sink rates of tungsten versus brass bead nymphs.

The table below shows that the two flies tied with tungsten beads sink at over three times the speed of flies tied with brass beads.

rod and reel yoshi nakagawa rene vaz fly fishing sink rates competition fishing trout flies tungsten beads

Furthermore the graph shows that there is little difference between the two flies of 0.6 or 0.8 grams in either tungsten or lead. And in fact, the major differences that occur are only due to the density of materials versus the overall weight. Interestingly enough this becomes a critical piece of information for anglers wanting to tie fast sinking nymphs whereby traditionally anglers have fished larger and heavier flies in order to get to the bottom quickly. This research however shows that small high density flies will in fact sink faster than larger and heavier patterns. As we can see above, the 0.6gram Tungsten nymphs sink more than twice as fast as the 0.8gram brass nymphs.

What is also interesting to note in the graph is the acceleration that a fly goes through in reaching maximum sink speed. Yoshi states that one important skill he has learnt from his shortline nymphing is to drive the nymphs into the water, that way the flies reach their maximum sink rate quicker, and consequently get down faster. If the flies are feathered down to the water they spend too long reaching their maximum sink rate.

Yoshi states that as a result of this research he has started to rethink his fly collection. Especially as over recent years where he has tended towards using shortline nymphing techniques. What has been critical in creating an effective fly collection is a range of patterns of differing weights and densities. Many of the successful patterns designed by the French, Czech and Slovakian anglers are tied with much slimmer profiles than the more traditional New Zealand patterns leading to faster sink rates effectiveness in fast and deep rivers.

rod and reel yoshi nakagawa rene vaz fly fishing sink rates competition fishing trout flies tungsten beads

What is vitally important in fly selection is getting an understanding of what your fly is actually doing. Yoshi’s advice to anglers is to cast your flies into clear water in front of you and watch how fast they sink. Being able to visualize the flies sinking and having an idea of how deep you are fishing will give you a better concept of the sink rate and drift. It’s not always critical to have your flies on the bottom, however it is critical to understand what they are doing so you can either repeat your success or adjust your approach. It is too easy as an angler to assume that you are fishing correctly when in fact you have no idea.

Of interest to many has been comparisons between different qualities of tungsten beads on the market, as all tungsten beads are made with a percentage of steel to give them strength. Sink rates are greatly altered by the amount of steel used within the bead and often lower priced or discount beads on the market look attractive and in fact they may still be heavier than brass beads. As Yoshi points out, it is important to understand exactly what you are buying as there is often a sacrifice for paying acheaper price and when you are looking for the ultimate sink rates, the premium product certainly makes a difference.

With so many channels for his fly fishing obsession it will be interesting to follow Yoshi’s progress in all of his endevours over the next few years. At the time of writing we have just heard that Yoshi has taken the gold medal at the recent Oceania Fly Fishing Championships held here in New Zealand, winning with a perfect score of five wins out of five sessions. Not stopping there, Yoshi mentions that he’d still like to win a New Zealand national competition sometime soon which despite five consecutive top ten placings, has eluded him thus far, and there is always the world champs, who knows? With a clearly different view point to so many anglers and an eagerness to understand the truth behind the assumptions that we all make as anglers it’s clear that all things are possible for Kiyoshi Nakagawa. Let’s hope that if he does take a world championship gold some day he will be wearing a Kiwi cap.