Mine works great at slower speeds. Below 50mph. But after the hull starts airing out, forget it. Just too much air to get a good reading.

Darrell.

Yes but if you find that spot put the transducer in a large zip lock bag full of water with the boat in the water. Move the transducer around until you find it reads. That is excalty were you need to glue in in place. Be absolutly sure you DO NOT get air bubbles in your glue or the transducer will never read.

On a step bottom boat the transducer has to be in front of the front step or it will never work at any speed.

I do appreciate all the input on this, I will be moving the transducer up in front of the first step. That is where the forward bilge pump is. I know that I'll lose the reading at certain speeds, I'll just make sure I'm below that speed when I'm in unfamiliar water.....It definetly beats driving by feel :D ...That tends to be rough on the outdrive...

So the 'ducer can read as you move it around the hull bottom while the boat is in the water. If there is any air between the ducer and hull bottom it will not read, thus the bag of water.

I just installed one on a 42 fountain. I installed it under the cabin step, right in front of the first hull step(same place factory installs it. I had to mount it about 4inches from the keel, because the center of the boat was cored. The customer said in flat water it was reading at 50mph.