11-07-2005, 01:09 AM
Hey smallmouth89,
You are understanding your Humminbird's functions correctly. Mine is the same way - basically.
Think of the beams from your fishfinder like the beam of a flashlight. The 20 degree is a narrow intense beam, like a spot light. The 60 degree is a broad more diffused and less intense beam, like area lighting.
The solid fish figures are the ones directly under you - those are the fish in your 20 degree beam(that's the higher frequency beam). The 20 degree beam is the one that goes down the deepest.
The hollow figures are the ones in your 60 degree beam(that's the lower frequency beam). This is the beam that covers the most area.
The coverage on each beam is as follows(if you'll remember some of your geometry from school):
The 20 degree beam is measured at the widest part of the beam - that will equal little over 1/3 of the depth you read(actually it's about .35 - or a circle of 10feet(depth) X .35). In other words, if the depth is 10 feet, the cone will cover a circumference under you that is a little over 3 feet in diameter. At a depth of 4 feet that would be a cone on the bottom of about 1and 1/3 foot diameter on the bottom.
The 60 degree beam puts a circle on the bottom that is roughly about(just a little bit over) the same diameter as the depth(actually the number would be 10 feet X 1.15). Or, if the depth is 10 feet, the cone on the bottom is about 10 feet in diameter. At a depth of 4 feet the cone is a little over 4 feet in diameter on the bottom.
To follow a contour of a specific depth - for example, a breakline(like a submerged roadbed), a drop off, or a deep weed edge, you can use a GPS and mark spots along it(this is difficult to do in a tube while fishing though). Or, use bouy markers that you can buy them fairly cheaply - Or, make your own very easily and even more cheaply.
If possible, scout out the area to fish in advance - get a map of the area before hand(this is the easiest way). Or, you can kick back and forth(in a serpentine or figure "S" fashion) across the contour and throw markers as you intersect the different depth changes.
[signature]
You are understanding your Humminbird's functions correctly. Mine is the same way - basically.
Think of the beams from your fishfinder like the beam of a flashlight. The 20 degree is a narrow intense beam, like a spot light. The 60 degree is a broad more diffused and less intense beam, like area lighting.
The solid fish figures are the ones directly under you - those are the fish in your 20 degree beam(that's the higher frequency beam). The 20 degree beam is the one that goes down the deepest.
The hollow figures are the ones in your 60 degree beam(that's the lower frequency beam). This is the beam that covers the most area.
The coverage on each beam is as follows(if you'll remember some of your geometry from school):
The 20 degree beam is measured at the widest part of the beam - that will equal little over 1/3 of the depth you read(actually it's about .35 - or a circle of 10feet(depth) X .35). In other words, if the depth is 10 feet, the cone will cover a circumference under you that is a little over 3 feet in diameter. At a depth of 4 feet that would be a cone on the bottom of about 1and 1/3 foot diameter on the bottom.
The 60 degree beam puts a circle on the bottom that is roughly about(just a little bit over) the same diameter as the depth(actually the number would be 10 feet X 1.15). Or, if the depth is 10 feet, the cone on the bottom is about 10 feet in diameter. At a depth of 4 feet the cone is a little over 4 feet in diameter on the bottom.
To follow a contour of a specific depth - for example, a breakline(like a submerged roadbed), a drop off, or a deep weed edge, you can use a GPS and mark spots along it(this is difficult to do in a tube while fishing though). Or, use bouy markers that you can buy them fairly cheaply - Or, make your own very easily and even more cheaply.
If possible, scout out the area to fish in advance - get a map of the area before hand(this is the easiest way). Or, you can kick back and forth(in a serpentine or figure "S" fashion) across the contour and throw markers as you intersect the different depth changes.
[signature]