[chumbucket]

chipde, they work pretty well when mounted in the hull. You shouldn't need to buy another transducer. Just remove yours from the transom, find a spot suitable in the bilge where it'll point straight down. Then what I did was to use a cardboard tube cut to the angle of the hull but level on top, probably 2" tall. Fill the cardboard with a thick two part epoxy, then set the transducer on top of the epoxy. You mainly want to make sure that there are no air pockects because they will affect the sonar signal.
You can try this setup before commiting yourself with the epoxy buy filling a large ziplock bag about 1/2 full of water. Have someone hold the transducer on top of the bag while underway to see how it works.