Transducer

Depth changes at higher speeds in 8 ft shows 52 changes when I hit 15 mph

Humm,,,,,,,,,,,,,,,,, ? If you were getting good readings before now, something changed. Did the transducer shift out of position? Is it still aligned correctly?

What you are experiencing is called “cavitation”

It is air bubbles coming from your hull. Too many and your transducer cannot read through that airid water.

It is recommended to install your transducer so it is skimming the water in an area with least cavitation. Skimming means 50-75% of it is in the water at all speeds. Slower speeds it will be submerged obviously but cavitation gets worse with speed so at slow speeds most duecer installs work fine.

What duecer?
Has it ever worked above 15 mph (on plane)

Lots of good info at the link below. They are selling a product, but you can install a ducer (FBRM, note spelling ) correctly without it.
http://www.sternmate.com/Where.html

Oh man I always spell it wrong

Still waiting for Lowrance to help with my transducer placement on the transom. Have learned a few things:
1.should not be located near a strake
2. should be located to the port side of the motor.
3. different transducer angles should be tried when the boat is on plane
4. a mounting board helps by putting the transducer a bit further away from the transom.

Spoon Minnow wrote:

Still waiting for Lowrance to help with my transducer placement on the transom. Have learned a few things:
1.should not be located near a strake
2. should be located to the port side of the motor.
3. different transducer angles should be tried when the boat is on plane
4. a mounting board helps by putting the transducer a bit further away from the transom.

#2 is bogus. Doesn’t matter which side your transducer is on. Supposedly that was because of prop wash being less on the port side because of prop rotation direction, but the prop and the prop wash is behind the ducer, so it makes no difference. I have one on each side.

Good to know.

You can learn from the manual what lowrance told you…. You can wait for the spoon or start feeding yourself Minnow