Vince Marinaro fished bamboo, mostly 4-weights and lighter, and the anglers who’ve read him tend to treat that as a charming artifact of an earlier era. But Marinaro wasn’t being romantic. He was solving a problem — presentation on flat water to fish that had seen everything — and the solution was less rod, not more. The limestone creeks he fished in the 1950s aren’t that different from the spring conditions you’ll face this month on any freestone with a decent Hendrickson hatch.

A trout’s lateral line registers pressure changes as small as 0.1 microbars — roughly the disturbance created by a size 14 dry fly landing on the surface at the end of a 40-foot cast. The difference between a 4-weight line and a 5-weight line hitting the water at that distance isn’t dramatic by human perception, but it doesn’t need to be. It needs to be detectable, and it is. In April, when water temperatures sit between 50 and 55°F and Hendricksons bring cautious browns to the film for narrow two-hour windows, “detectable” is the entire gap between a committed eat and a fish that slides back under the bank without urgency.