Jerry, I would buy the best bronze transducer and Furuno bottom machine the budget will allow if you like to fish. Check out the new Furuno Navnet 3 electronics. That is some cool stuff, more than I can afford right now. The chartplotter redraws instantly and has 3D viewing. There are a lot of less expensive, quality products on the market. I don't see why someone would need a dual range transducer and temp if fishing is not in the plans. I think the speed would be important, you could look at the GPS for speed over ground, and the transducer for speed through water. This would be helpful in areas with a lot of current. You might need a fairing block, depending on the hull deadrise where you want to mount it.