We just got back from 19 days at Siltcoos, fishing at Siltcoos has been on a downswing (overfished?). We started fishing Woahink instead, before the official news of the alge bloom hit. We had an 80+ day, a 100+, a 60+ day and some 20-30+ days with a day to rest our tendinitus afflicted elbows from jerking perch from 50' down. We were able to use the fish finder to locate fish and sit down on them, if you can't locate the fish with the finder adjusted properly it's a crapshoot and you will get very few perch.
This is a photo of a perch being jerked from the mess of perch from 48.5'-50.7'. The line going strait up mid photo is our line with perch attached. The other red orange blue line going up and comming down is another perch going up for the stomach contents of the caught perch I'm guessing.
This photo shows a perch going from 50.2' up to 40' to grab a piece of discarded bait, old worm. At the bottom of the photo, the two black lines are sinker and bait, bait on the bottom. There are four perch in the photo comming up from the bottom to check things out, many times they seemed very curiuos about our sinkers. The bottom of the photo shows many perch from 48-50'

When there was a mass of perch like this the fish would bite as soon as you got your bait into them, lots of times you'd see perch commong out of the mass, ten feet up to get the bait before it got to the mass at the bottom. Somtimes when there were only two or three perch on the screen you had a hard time getting them to bite, sometimes you couldn't. They were like little sharks, when in mass the would frenzy feed!
The keys; High pixel count finder, 480x480, color would be best. I think if you running 240x240, or less, it may be tough to get a good picture, zooming may help though. Turn finder to maunual mode, if your seeing little fishie shapes on the screen you've got it wrong. Turn sensitivity to maximum. Turn zoom to maximum, mine is 4x on this finder.
Water clarity in Woahink is what made all this possible, when you turn a finder to maximum sens. in cloudy water in may be impossible to get views like these. I never did put the boat back in at Siltcoos to see if I could get results like this there.
Smj