Garmin vs Lowrance

[Riccochet]

could be the freq and scroll speed you are using. turn off chirp and use straight 200

I'll give that a shot this weekend. Thanks!

[Larry3215]

You usually get better penetration with lower frequencies, so if 200 doesnt work, try the lowest freq the transducer will let you select and up the gain.

[mcbassin]

You usually get better penetration with lower frequencies, so if 200 doesnt work, try the lowest freq the transducer will let you select and up the gain.

So you're saying change the frequency every time we make a run? I have the same unit as you on my console Larry. Are you running a shoot thru transducer?

[Riccochet]

the only thing I use my GT15 shoot-thru for is reading depth at speed. If changing the frequency on just that transducer solves my issue then I'm all for it. I have a GT52 on the transom for actual fishing.

[Larry3215]

So you're saying change the frequency every time we make a run? I have the same unit as you on my console Larry. Are you running a shoot thru transducer?

No in-hull or thru-hull - I just have the GT51 on the transom and it reads bottom in normal CHIRP mode at my top speed of about 35 or so, so I dont have a need for one.

In your case, its going to be much more difficult to read bottom at 50-60 mph - especially with a transom mount transducer. Its even more complicated if your hull is stepped.

In your case, an in-hull or thru-hull would almost certainly work a lot better than a transom mount at those speeds. A lot will depend on your hull (how its constructed, thickness, layers, etc) and exactly where you mount it. Its very important to test locations before you commit with an in-hull/shoot-thru hull type.

For a true thru-hull (through an actual hole in the hull) the main thing is to be sure there is nothing ahead of the location that can cause turbulence, bubbles etc.

My comment about frequency was a general thing. Lower frequencies always penetrate thru water better than higher frequencies. In the case of the GT15, it has a range of 85-165, so if CHIRP mode doesnt work, and your mfd will allow it, try a lower fixed frequency and see if its better. Lower should work better than higher, but I have read of cases where higher worked better. Probably had something to do with how the hull was constructed Im guessing. In any case, it wont hurt or take long to try all the options.

If it still doesnt work, you might consider removing it from the housing and testing other locations using the baggie filled with water method or going to a true thru-hull type ducer. Also check to see there is nothing ahead of the GT15 on the bottom of the hull that could be causing any turbulence.

Oh - and be sure the gain is turned up :)

[Larry3215]

the only thing I use my GT15 shoot-thru for is reading depth at speed. If changing the frequency on just that transducer solves my issue then I'm all for it. I have a GT52 on the transom for actual fishing.

Thats about all a shoot thru hull type is good for. They almost never make for good fishing returns. See my comments above - they apply in most situations.