Your first decision should be the method of mounting the Transducer in the boat; there are 3 to choose from...
- Transom Mount - this is the simplest and cheapest way. The Transducer is simply fixed (screwed) onto the back of the boat (just below the waterline) and the cable is run over the stern or through a hole (fitted with a gland) and on to the display.
- In-Hull Mount - this method has the advantage in that it can be fitted with the boat in the water. The Transducer housing is fixed (glued etc) inside the bottom of the boat.
- Through-Hull Mount - this is best of all BUT requires an approx 51mm/2in hole to be drilled through the bottom of the boat. Obviously the boat must be out of the water to do this and the hole must be coated with a good sealant to ensure it is water-tight.
The second decision is the connection to your Chartplotter or FishFinder...
- 4pins - this is used on the current "echo" range of Garmin FishFinders
- 6pins - this is common on many current and recently discontinued Garmin Chartplotters and FishFinders
- 8pins - this is common on the new range of Garmin GPS/Chartplotters.
The third decision is Technology used...
- Traditional -this has been the standard technolgy since Depth Transducers have been available
- DownVu - this gives a clear, nearly photographic quality sonar view below your boat
The last decision is Brand name - the company "Airmar" seem to make most of the Transducers for most of the manufacturers!!! So where there is a choice, you can choose a genuine "Garmin" branded product OR the "Airmar" branded product (which is usually exactly the same Transducer unit but probably with a different length cable and usually cheaper).
At Hamble Marine, we stock options for all the above.