Wikipedia says that the English phrase “rule of thumb” refers to a principle with broad application that is not intended to be strictly accurate or reliable for every situation. It references an easily learned and easily applied procedure or standard, based on practical experience rather than theory. Webster gives us two meanings that are much simpler to follow: First, a method or procedure based on experience and common sense; second, a general principle regarded as roughly correct but not intended to be scientifically accurate.
The phrase itself has been said to derive from the belief that English law allowed a man to beat his wife with a stick, so long as it is was no thicker than his thumb. Interesting concept, but let’s not go there. Some have tried to link it with brewing. Supposedly, in the days before thermometers, brewers gauged the temperature of the fermenting liquor with their thumbs. Wherever they came from, there is a rule of thumb for just about anything and everything, but let’s talk over some of the rules of thumb used in fly fishing.
What color fly should I use? If you are fishing salt water in low light conditions (early mornings, late evenings, or cloudy weather), the rule of thumb is to go with darker colors in your fly patterns. The reasoning is that the silhouette will be easier seen by the fish. This holds true for off-color water also. Whether it’s dark by being tannic or dirty from rain or wind, a darker color fly will be easier seen by the fish.
On a bright sunshiny day with clear water, the rule of thumb is to use lighter colors and more sparsely tied patterns. Trying to match the color of your surroundings is a “thumb thought.” If you are fishing over a sandy bottom, light tan is a good bet. Fishing over grass? Maybe an olive would be the ticket.
I see it all the time with clients who go fishing with me for the first time. They are putting their fly rod together and ask “Captain, what color fly today?” When I tell them to wait until we get to the area we are going to fish and we’ll see what our conditions are at that point, you should see their faces — disbelief and sometimes total shock. Of course, I have an idea of what we are going to use because I’m on the water so much, but it’s a good teaching tool to have them tell me what they see and choose accordingly. Rule of thumb: Use what Mother Nature gives you today.
Color or size can make the difference between getting a few bites a day and getting epic eats with non-stop action. This is why you should have a spectrum of colors for each pattern you have. I always have different colors of a fly pattern (natural, dark, bright, and at least one multi-color) in my box. Another thing to think about is what is the main forage of the fish you are targeting on that trip. Every type of forage out there will occur in different sizes and colors depending on the conditions of the area you are fishing.
Rule of thumb for topwater flyfishing: Don’t set the hook until you feel the weight of the fish. Topwater has been a blast lately throwing gurglers, poppers and crease flies, with fish blowing up on them. There is nothing more exciting than an explosive topwater crush! But that blowup produces a lot of adrenaline in people, and then they want to react to that adrenaline rush in ways that aren’t conducive to hooking a fish.
This to me is more than rule of thumb — this is a law. Don’t react to the blowup. Keep the rod tip down, keep stripping, and wait to feel the fish on before you strip-set and lift the rod for the fight.
One or two refusals on a fly means it time for a change. Maybe the problem is your retrieve, so change it up. Go faster, slower, pause in between every couple of strips …whatever it takes to get the eat. Still not working? Change the color, or go up or down a size. If this doesn’t get results, then change the type of fly, maybe from a baitfish to a crab. Keep changing things until something works!
As a passing thought, but still a very important rule of thumb: If you see a pelican standing on a flat, don’t run your boat there — it might be shallow! Isn’t that right, owner of the Key West with a 90-horse Yamaha? I was glad to see you stand up after being thrown out of your boat.
My rule of thumb on fly effectiveness: Presentation is most important, and it’s all up to you. How well you cast, and how you make the fly look alive and real enough to eat, really matter. Sometimes a good presentation with the wrong fly will still get bit! Next in importance are the size and profile of the fly (matching the hatch, ya know), and then comes color.
One last rule of thumb: A day of fishing beats a day of just about anything else! Let’s get on the water and enjoy, and remember:
Capt. Rex Gudgel is a fly fishing guide in the Boca Grande area and an International Federation of Fly Fishers Master Certified casting instructor. If you’d like to get casting lessons, book a trip or just need more fly fishing info, contact him at 706-254-3504 or visit BocaGrandeSlamFlyFishing.com or CastWithRex.com.