confidence & confusion with the fish finder

today was my 3rd time out in the salt - gets different each time - each time i become aware of a few more things, pretty cool

i finally got my FF rigged and used it last week and today (huminbird 383c) - during both outings, i noticed that there were specific locations, where the FF would read a depth that i knew was incorrect - for instance it would say 10 feet or so, when i knew i the water was way deeper.

so, this inconsistency has me wondering about how accurate my FF is general when it comes to depth, and the new one i'm wondering about is speed...today couldn't believe how fast i was going without hardly paddling, though there was a good tide push

so what gives?  i'd like to be able to feel confident with both depth and speed, but i'm really just scratching my head at the moment looking for answers

as an FYI, my transducer is mounted on a small sidtrack board outside the boat in the water

thanks!

anthony

The same thing happens to me from time to time out in the salt as well.  My theory is that its a harbor seal checking me out from below... at least thats the lie I tell myself.

Things is when other boats are on the water and they're using fishfinder it can interfere with your's. And the speed is all about current. Next time you're on a lake you'll see readings a lot more consistent.

Z

When it "knowingly" reads wrong, does the depth also blink?  Mine was doing this and turned out to be a dud for a 'ducer.  Replaced it and I only get funky readings in less than 1 foot of water, as expected.

After the yak is in the water, wipe your hand across the transducer.  Somtimes bubbles will adhere to it.  Does your unit have a salt water setting?  Does your unit have a maximum depth setting, if so, try lowering it.  Do you really need to read down to 1000 feet?  There may also be a sensitivity setting, if so, try lowering it a click or two.  Maybe you are reading a thermocline or a layer of schmutz as the bottom.   

If speed is based on the GPS and there is a good tide, don't be surprised about your speed.  Wait until you have to paddle hard against the current and look down to see that you're speed is near zero.

Bait balls, thermoclines, even zooplankton blooms can all give false bottom readings if your sensitivity settings are off.

Testing it out and mucking around with the settings on a nice clear lake isn't a bad idea.

For the first time I experienced what antpo describes.  Was off Richmond beach in 200+' of water and suddenly the depth was jumping around and reading 10', 2', 16', ... After a minute it clears up, then repeats at random.  I marked the location on the GPS and sure enough second pass through the area same thing happened.  Last night there was lots of schmutz on the water along the tide lines, and lots of weak but extensive signals from depth which I interpreted as layers of similar detritus.  Also a harbor seal in the area.  Do they ever shadow a boat?  Play under it?  Bump it?