Hi folks,
Im going to be fishing in Lake Chelan this coming week. Ive been told the best bet for lake trout is to troll with your downrigger ball about 5 feet off the bottom. This is in 250' to 350' depths using a 15# to 20# ball.
Ive done some tests locally in salt water and I can easily see the ball and get a depth reading on it as well as see where it shows on the screen in relation to the bottom.
However, while trolling the ball is well behind the boat - 20 or 40 degrees easily. Im assuming that, because of the blow back, the ball will not actually be where it is shown in relation to the bottom. I have charts to make allowances for the blow back of the balls while trolling. So I can get a pretty good idea of the actual depth of the ball.
My question is - is the bottom depth shown on the unit in 2D mode the actual depth under the boat at that precise point or is it an average of the depth over the entire cone of coverage area or is it the shallowest point within the area of the cone or something else? I will be fishing in areas where the bottom has a significant amount of slope with some pretty dramatic depth changes.
I suspect the guys who are giving this advice are just looking at the screen and keeping the ball what "looks like" 5' off the bottom as shown on the screen. In other words, Im probably way over thinking this
Im still curious about how the sonar unit determines the actual depth - especially when the bottom is irregular right under the boat. Any tips or info would be appreciated.
Thanks,
Larry
Im trying to figure out how to keep my gear within 5 feet of the bottom