© 2020
|
Johnson Outdoors Marine Electronics, Inc.
|
cannondownriggers.com
39
BLOWBACK CALCULATIONS
Blowback is created by the resistance of the water to the downrigger Weight and Line as you pull it through the water behind your
boat. When the speed of the boat is increased the horizontal distance behind the boat also increases. This causes the Weight to move
shallower, so more Line needs to be released from the spool to get back to your target depth.
The following charts provide you with approximate blowback information for three sizes of Cannon downrigger Weights pulled at three
different speeds with no lures attached and with no current in the water. Water current, water current drag, water salinity and the use of
non-Cannon products will affect your actual trolling depth and blowback.
As an example, the first chart shows that if you are trolling at 4 mph with an 8 pound weight and you have 100 feet of line in the water
with no current; the downrigger Weight is actually at a depth of about 80 feet.
Line Length (ft.)
0
20
40
60
80
100
120
140
160
0
20
40
60
80
100
120
140
160
8-Lb Weight at 2, 4, and 6 mph
mph
2
2 mph
mph
4
4 mph
mph
6
6 mph
mph
Ac
tu
al D
ep
th O
f W
ei
gh
t (
Ft
.)
BLOWBACK
Line Length (ft.)
0
20
40
60
80
100
120
140
160
0
20
40
60
80
100
120
140
160
10-Lb Weight at 2, 4, and 6 mph
mph
Ac
tu
al D
ep
th O
f W
ei
gh
t (
Ft
.)
2
2 mph
mph
4
4 mph
mph
6
6 mph
mph
Line Length (ft.)
0
20
40
60
80
100
120
140
160
0
20
40
60
80
100
120
140
160
12-Lb Weight at 2, 4, and 6 mph
mph
Ac
tu
al D
ep
th O
f W
ei
gh
t (
Ft
.)
2
2 mph
mph
4
4 mph
mph
6
6 mph
mph
NOTICE:
These tables are approximate and may be
affected by water current, water current drag, water
salinity, trolling depth and the use of non-Cannon
products among other things.
