Depth Offset

[Carl]

How is the best way to determine the water level prior to going to the lake? Do you have to use your depth finder and map chip to do the off set depth of a lake? I have a HB 798 and a Lakemaster chip.
Any information on this subject will help.

[CrappiePappy]

Carl ... I usually look here : Lake Levels and/or a website for that particular lake, or the website of the state/fed agency that controls the lake level. I use this one
Louisville District Daily Lake Report for local lakes ... and it shows the fluctuation levels for the previous 12 months.

Reading your title ... I thought you were going to ask how to set your DF's depth to compensate for the depth of your transducer Rofl

... cp

[Carl]

I've looked at the lake levels and don't understand how to reead them. I guess my question was a 2 fold question the other question would be "how to set your DF's depth to compensate for the depth of your transducer"?

[CrappiePappy]

Carl .... on the Lake Levels link - find your lake, then look at the "Full Pool" number .. that's the Summer Pool level, which is what any map's depth reading is based on. So, if your map says the water is 20' deep at a certain spot ... it's 20' deep ONLY when the lake is at Summer Pool.
Then look at the "Current Level" number ... that tells you what the lake level is "now" (when last measured). You can see when it was last checked, under the "Reading Date-Time" column. The "+/- Full Pool" column tells you, at a glance, whether the lake is below or above Full Pool and by how much (measured in feet).

Once you know that the lake is up/down X number of feet ... you have to add/subtract that from what your map is saying the depth is. Then you'll know whether that 20' deep spot, on the map, is actually deeper or shallower and by how much.

Your DF will tell you how deep the water is, where you are on the lake, and you can figure out all that "lake level" info by just comparing the depth on the map against the depth showing on the screen.

That's where knowing how deep your transducer is, in the water, comes into play. It's usually only a foot to 1.5ft below the surface. Knowing that, you can simply add that distance to whatever depth the DF is reading, and you'll know the actual depth from surface to bottom. You also need to take into consideration that the transducer is reading the depth of the fish/cover/bottom from where IT is, and not from the surface of the water.

Look at it this way : Say your DF shows a fish that's 15ft deep, and you want to put your bait right in front of it. If your transducer is on your TM, and it's 1.5ft below the surface ... then the fish is ACTUALLY 16.5ft deep (from the surface). So, if you're fishing with a float, you'd want to set your bait 16.5ft below the float. Or, if you're pole is hanging off the side of the boat or in a pole holder ... you'd have to add the distance the rod tip is above the water's surface, to the 16.5ft actual depth of the fish, so you would have the correct amount of line out to get your bait in the fish's face.

That's just the laymans way of figuring "actual" depth of what the DF is telling you. I believe there is a way to set a DF to compensate for the depth of the transducer, and I think this is how you do it for a 798 :

Go to Advanced user mode, then to Main Menu ... under SETUP Tab is the Depth Offset ... you can adjust the depth reading by adding the depth that your transducer is below the surface of the water. THEN all the depth/cover/fish readings will be "actual" depths as measured from the water's surface, and not from the transducer.

... cp

[Carl]

Thanks crappiepappy thats just what I needed.

[LBM]

Carl crappiepappy has it nailed and spot on with his answer to you.

I'm not sure how you fish but when I first started crappie fishing I was interested is how to set the Depth Offset on my graph and finally realized as for me it really didn't matter that much since my trolling motor depth it is running in the water is continually changing as it always eventually slips deeper into the water over time. When it finally slips to its maximum depth I'll adjust it up shallower since I don't like it running that deep where I can't see the underwater stobs that I'll run into. I think Minnkota sells an additional attachment that will more securely hold the trolling motors depth setting.

Now for some of the reasons I didn't find it necessary to set the Depth Offset. I normally tight line hover with rods in both hands. If I'm working suspended fish where I can see scattered individual fish marks on my graph it tells me at what depth they are running. At what depth they actually are suspended at doesn't really matter because I can also see the depths my baits are running on the graph. I them make sure my baits are running at the same depth I'm seeing my fish marks.

If I've established that there are fish on the bottom to be caught at a given depth it doesn't really matter what the real actual depth is as long as I stay where my graph shows that given depth.

Again if I've established there are catch able fish on a break from say 15 ft into 20 ft as shown on my graph it still doesn't really matter if those actual depths are 12 and 17 or 19 and 24 as long as my graph shows it at 15 to 20ft.

Just my thoughts on this which now definitely confirms my lazy indolent approach towards fishing where I try and catch fish with the very least or minimal amount of input efforts towards actual catching and which those that already know me are well aware of.

[Hanr3]

I crappie fish the most. Crappie feed up, in that they look up for food becasue their eyes are more above the nose per say nad its is easier for them to see food above them. I read the depth on my sonar unit to the fish crip, fish and set my depth to match. That puts my biat about 1' above them. Now when they come up to take the bait, they will naturally head back down to where they were to eat. This causes my bobber to go under and I know without a doubt I have a fish on.

The only time it bothers me is when I travel through shallow water to get to another spot and the depth finder shows 2 foot or less. I have to remind myself the propr is aobut another foot depper than the transducer. I have replaced teh shear pin at least once per year while on the water.