Trigonometry pays dividends by playing the angles in salmon fishing

on May 02, 2014 at 6:00 PM, updated May 02, 2014 at 8:25 PM
FishingAngles for angling aren't rocket science for former (and current) math students.
I remember very little about high school trigonometry, other than the teacher was tough enough she could have played Dorothy’s bicycle-riding, wicked-witch “Miss Gulch” in Wizard of Oz.

Trig was a “solid” in those days; courses (Latin, math, physics, biology, etc.). We endured solids to please our parents’ dreams about us becoming rocket scientists and brain surgeons.

But practical applications as an adult? Isn't angling really more about fishing than math?

How deep?” I shouted the other day to the guy on the kicker of a boat we passed after he told us they’d caught a hatchery spring chinook salmon. “20 feet,” he shouted back.

OK, Miss Gulch, I can do that. Imagine a right triangle created by the line angling back to the bait or lure, then horizontally back to a point directly below the boat and then 90 degrees vertically to the tip of the rod. That last leg, minus the rod tip's distance above the water, is then the depth of the bait or lure.

You adjust the angle of the line with both the weight and the trolling speed. If it's 30 degrees, the sine (constant ratio of an angle in a right triangle to the opposite side) of a 30-degree angle is .5, so therefore…if the hypotenuse, or the amount of line out, is 40 feet, then the depth, or the side opposite, must be 20 feet.

Yup, trigonometry.

It actually works well in the kinds of relatively shallow depths of the Willamette River. Deep water, of course, adds parabolas, line arcs and calculus. I drew the line at calculus, wicked-witch be damned.

(Think downriggers. I have two for saltwater. No math required.)

In a crowd, where you don’t want your tangling with another boat, you can add weight and troll at a 45-degree angle. Since the sine of a 45 degree angle is .707, use a simple algebra equation to come with how much line it will take to multiply by .7 (in fishing, unlike rocket-science, it’s OK to round off) and get to 20 feet (about 28.6).

I used to use the Pythagorean theorem to do depths. You may recall it says the sum of the squares of the two sides of a right triangle is equal to the square of the hypotenuse.

Calculating square roots in my head killed a lot of time between bites, but then fishing got better and I resorted to much faster trigonometric calculations.

Today's smart phones make it even easier. I can simply look up all the sines and cosines then use the calculator while someone else steers.

I thought about my solids this past week on a turkey hunt while using my iPhone to carry on a live email chat with my brother in Kenya as I waited for dawn. The only thing it wasn't smart enough to do was tell me I'd parked in a patch of poison oak.

Still, it occurred to me if you’d told me back in high school that someday, instead of rocket science, I would chat as if we were across the room from each other with my brother in Africa while listening to turkeys gobble in Oregon, well…

…I'd have figured there was about as much chance of that happening as actually using algebra, geometry and trigonometry to go salmon fishing in downtown Portland, Oregon.

Happens every year: The game of tag is running to a conclusion with more than two-thirds of you still waiting to touch the Oregon Department of Fish and Wildlife’s big game application process.

The deadline is May 15.

With a 2 percent increase in total tags this fall, most of them deer and elk, those who match last year’s 382,406 applicants might stand a bit better chance of getting a hunt they want. There are 143,198 tags proposed for approval by the Fish and Wildlife Commission in June, compared with last year’s 140,807.

However, as of Wednesday, only 103,505 applications were filed, actually a little up from 100,638 by the same time in 2013.

Avoid a long, last-minute wait by going online.

The department is warning hunters about new access fees on lands owned by Weyerhaeuser Inc. (and some in Washington) Not all tracts will be in the program, but it does include the popular Molalla Tree Farm.

More information is available online from Weyerhaeuser.

-- Bill Monroe