I installed my HDS 8 with 50/200khz transducer back in August, and have had no problems with it - that is, until I started trying to explore some of the more advanced features and realized I have an issue with operating in 50khz.
I can get a decent return in 50khz at idle speed, but once up on plane the signal goes to crap. 200khz seems fine, I’ve never lost the bottom at speeds up to about 40 mph, even in some decent chop. Kind of puzzled by this, because everything I know about sonar theory says that 50khz should be less sensitive to poor conditions than higher frequencies. I’ve included some screenshots below (hopefully, never tried posting pics before…)
I’ve checked all the basics I can think of:
transducer location seems OK, I used the existing mounting holes from a previous owner (don’t know what type of unit was on the boat then) but the placement is within the ranges suggested in the installation instructions.
correct transducer selected in “Installation” settings
no other sonar, so it’s not a cross-talk issue
varying sensitivity settings, fishing mode, etc doesn’t really make much difference
My theories are that either the transducer is getting too much turbulence and needs to be moved, or that there is some sort of electrical interference that affects the lower frequency. Before I start drilling new holes and rerouting cables does anyone have any other ideas or things too look for? Thanks in advance!
Transducer location
at idle, 50khz on left side of sonar screen, switched to 200khz
switch from 200khz (left) to 50khz (right) at idle
I can’t tell from the photo, but is the trailing edge of the xducer higher or lower than the leading edge (straight edge from hull in relation to the seam on the side of the xducer)? I have had the best results with the trailing edge ever so slightly lower than the leading edge to keep a bit more positive water pressure on the face of the xducer. Also, as you get familiar with your unit you can overlay some of your GPS data into your sonar screens. These are great units but require a bit more time to master due to the added features. Also, looking at the photo I wonder if there are any live well / wash down intakes forward of the xducer location. And the xducer location looks closer to the engine than recommended in the manual.
No intakes forward of the transducer. The perspective of the photo distorts the actual distances a little, but yea I think it may be a little too close to the outboard horizontally. The manual is a little vague on the distance, it says no closer than one foot from lower unit - it’s definitely more than one foot away total, but not one foot off edge of prop radius horizontally. But, I wouldn’t expect that to matter much except when backing. My only concern with moving it out is that it will also raise it higher in the water, which may not be good either.
I haven’t played with the angle except to level it enough to get clean arches, I’ll try that next time I get it in the water.
I’m also planning to add trim tabs eventually which will take up real estate in the same area the transducer needs to go so maybe I should just solve this whole issue with a thru-hull transducer - anybody have any experience with the Airmar B60 50/200 khz 20 deg tilted element thru-hull vs the stock Lowrance transducer?
the airmar thruhull is a great upgrade
unless you fish really deep, the 600 watt will work perfectly, but if you want to see a big improvement, get the 1kw. major price difference between them
whatever you get, make sure you get the bronze thruhull, not the plastic
