Discerning Bottom Composition in Thick Grass

[DrewFlu33]

Anybody have any luck doing this?

I have gen 3 HDS units running LSS-2 and HST-WSBL combo at the console and an HDI at the bow. I'm hoping to find hard bottom areas on weed flats ranging from 5-18 feet deep (mostly 8-15) with a mixture of milfoil, coontail, and just about anything else that grows in MN. The vegetation is THICK and the water is clear with at least 8 feet of visibility.

The background:
Every year I start out my season promising myself I'm going to go out right after the ice is off to graph the areas on my tournament lakes that end up weed choked by the time tournaments get going to find bottom transitions, then I never manage to find time to do it. So here I am, about to fish a lake that I have struggled mightily on in the past but where I know there's a winning pattern waiting to be unlocked. Quite honestly, figuring this out would pay off in a huge way just about everywhere I fish, but this lake in particular has had my number. It's a lake that has unreal numbers of dinks - 100 fish days are not uncommon - but where the relative few big fish in the lake school up together in what seem to be random areas on giant weed flats. We're talking tournaments where you'll have 20 guys with 5-9 lbs with most usually clustered around 7 lbs (EVERYONE catches a limit) and one or two guys who will roll in with 15-20+ lbs absolutely demolishing the field. It's unbelievable, and what's more is you know general areas they fish and the techniques they use yet still can't replicate it. I'm certain that the spots they school up on the weed flats aren't random as guys can repeat their success year after year and different guys will catch them different ways, but I just don't have time to go out and pick apart a 500 acre flat to find an area the size of my boat holding the fish, and as I mentioned I didn't manage to do my homework in the early season. I have to believe the fish school up in specific areas, and my bet is that it's the scattered areas with hard bottom or rock piles.

So, anyone have any luck doing this and/or tips for figuring it out? Or am I stuck hoping to land on a needle in a haystack and promising myself I'll go graph before the grass grows next spring?

My attempts in the past have been to dial back sensitivity to try to get the units to "ignore" the weeds then look for differences in the thickness of the bottom return, but the fact that the weeds aren't uniform means I end up just seeing areas with thicker/thinner weeds near the bottom.

[winnebasschamp]

Sorry to say, but get a vexilar flasher unit. Only thing I've seen that will shoot through thick grass to show bottom hardness well.

[Team Colibri]

Weeds usually don`t grow on rocks. :) In shallow water I typically use SideScan for this, where there is no weed there is usually hard bottom. Apart from that, you can easily identify hard bottom by:
Use 2D with the narrowest coneangle and hardest echo you have, typically 200kHz. Put your unit in manual mode and then set depth to 3-4 times actal depth. Look at the shadow-bottom, as seen here:



Soft bottom will not create the 3. and 4. shadow-bottom:

[Chief Brody]

Doesnt Lowrance have an ice ducer with a narrow cone angle?
maybe try it.

[Team Colibri]

Doesnt Lowrance have an ice ducer with a narrow cone angle?
maybe try it.

HST-DFSBL and 50/200-HDI are the Lowrance-ducers with the most narrow coneangle (12 degrees on 200 kHz). The ice-ducers are around 20 degrees.

[Macsimus]

Sounds like Prior.

[SlumpGumpy]

Dude i say the same thing every year at ice-out too
i’m gonna scan the whole lake and find those areas—never do it

Anybody have any luck doing this?

I have gen 3 HDS units running LSS-2 and HST-WSBL combo at the console and an HDI at the bow. I'm hoping to find hard bottom areas on weed flats ranging from 5-18 feet deep (mostly 8-15) with a mixture of milfoil, coontail, and just about anything else that grows in MN. The vegetation is THICK and the water is clear with at least 8 feet of visibility.

The background:
Every year I start out my season promising myself I'm going to go out right after the ice is off to graph the areas on my tournament lakes that end up weed choked by the time tournaments get going to find bottom transitions, then I never manage to find time to do it. So here I am, about to fish a lake that I have struggled mightily on in the past but where I know there's a winning pattern waiting to be unlocked. Quite honestly, figuring this out would pay off in a huge way just about everywhere I fish, but this lake in particular has had my number. It's a lake that has unreal numbers of dinks - 100 fish days are not uncommon - but where the relative few big fish in the lake school up together in what seem to be random areas on giant weed flats. We're talking tournaments where you'll have 20 guys with 5-9 lbs with most usually clustered around 7 lbs (EVERYONE catches a limit) and one or two guys who will roll in with 15-20+ lbs absolutely demolishing the field. It's unbelievable, and what's more is you know general areas they fish and the techniques they use yet still can't replicate it. I'm certain that the spots they school up on the weed flats aren't random as guys can repeat their success year after year and different guys will catch them different ways, but I just don't have time to go out and pick apart a 500 acre flat to find an area the size of my boat holding the fish, and as I mentioned I didn't manage to do my homework in the early season. I have to believe the fish school up in specific areas, and my bet is that it's the scattered areas with hard bottom or rock piles.

So, anyone have any luck doing this and/or tips for figuring it out? Or am I stuck hoping to land on a needle in a haystack and promising myself I'll go graph before the grass grows next spring?

My attempts in the past have been to dial back sensitivity to try to get the units to "ignore" the weeds then look for differences in the thickness of the bottom return, but the fact that the weeds aren't uniform means I end up just seeing areas with thicker/thinner weeds near the bottom.

[DrewFlu33]

Sounds like Prior.

Way worse than Prior! Not joking!



Appreciate the insight, everyone! I was actually able to use 2D to locate some harder bottom areas like Colibri mentioned and, although it was slow, it was faster than waiting til spring! Not sure why I didn't try that before. I know that trick with my flasher when ice fishing, should've realized it would work on 2D as well. The bad part is I still didn't find any good fish!

[Fishton]

Airmar P66 has a 9° cone

[DrewFlu33]

Aaaand bringing this full circle: I ended up catching two key fish on a soft/hard bottom transition I had located earlier in the week and won the damn tourney! A little over 9 lbs and won by nearly 2 lbs. Feels like I'm back in WV with those kind of weights (though I would've been ecstatic to catch 9 lbs in WV most times)....

[Marc Marcantonio]

Have you tried using the Insight Genesis mapping and using the bottom hardness layer? Makes the task much easier to see the relative hardness throughout the lake. Congrats on the win!

[Macsimus]

Congrats on the dubya

[DrewFlu33]

Sorry for the delayed response! I appreciate the congrats, gents. Thank you! It was definitely rewarding after having struggled so mightily on this lake in the past. The only thing that takes the wind out of my sails somewhat is that the day was still a struggle, I just happened to struggle a little less than everyone else!

Have you tried using the Insight Genesis mapping and using the bottom hardness layer? Makes the task much easier to see the relative hardness throughout the lake. Congrats on the win!

I actually bought it for a month just for this lake in the past. I think the reliability of those maps is tied directly to how many people use Insight Genesis and record sonar logs. Additionally the amount of weeds here probably makes those recordings not as reliable as they would be otherwise. Anyhow, sort of long story short, it was not reliable at all on this lake.