Fishfinder transducers are often a source of confusion among our customers. Let's try to simplify it.
There are three basic styles of transducers:
- Thru-hull - actually requires a hole to be drilled through the bottom of your boat to fit the ducer
- In-Hull - also called "shoot through" - these are epoxied or glued inside your bilge
- Transom Mount - these screw onto the transom
Each style of ducer has its benefits and drawbacks.
- Thru-hull (good) - offers best performance, usually includes temp sensor (bad) - requires a hole to be put in the bottom of the boat. Can be troublesome to replace.
- In-Hull (good) - is easy to install, boat can stay in the water during installation, least affected by turbulence (bad) - no temp capabilities, lose 30% of range
- Transom Mount - (good) - easy to install, easy to replace (bad) easily affected by turbulence, requires screws to be put into the transom which can compromise the transom core
Different styles of boats require different kinds of transducers. The text below is just a guideline, there are always exceptions. But generally:
- Inboard boats require an in-hull or thru-hull. Transom mount ducers will not work on inboard boats.
- Boats with cored bottoms require a transom mount or thru-hull. In hull ducers will not work.
- Metal boats require a transom mount or a SS thru-hull. In hull ducers will not work.
Cone Angle - What is it?
- Cone angle is the angle at which a transducer shoots down from your boat. Imagine a cheerleaders megaphone placed at the bottom of your boat. If you were somehow able to look down through this megaphone you would essentially have the same view a ducer has. A narrow megaphone (cone angle) will show a small portion of the water while a wide megaphone will show you a larger portion of the water. Typically a 200kHz single freq ducer will have a cone angle of about 20 degrees, and a dual freq ducer will have a cone angle of 12 degrees at 200kHz and 45 degrees at 50kHz. The shape of your megaphone will extend all the way to the bottom of the ocean, so a wider cone angle will show more of the bottom at one time.
Recently Airmar has released a series of Dual Frequency Ducers with a wide cone angle at both 50 and 200 kHz. These are very popular for the offshore trolling crowd. The wide angle at 200kHz allows fisherman to find great detail near the top of the water column while still covering a wide swath of water.
Dual Frequency vs Single Freq vs Dual Beam
- Dual frequency ducers (50kHz and 200kHz) are best for deeper water beyond 150'. The 200kHz signal is used up to 150ft then the 50kHz is used for deeper water as it can penetrate further. You will need a dual frequency FF to use one of these ducers.
- Single frequency ducers (200kHz) are best for water below 150'. If you primarily fish in water less than 150' you are better off with a 200kHz ducer than a 50/200kHz ducer as the cone angle is wider than a 50/200kHz ducer operating at 200kHz.
- Dual Beam ducers are 200kHz ducers that actually "listen back" for a 83kHz signal. All ducers have this 83kHz signal (which has a very wide cone angle) but most filter it out. A dual beam ducer actually looks for this signal. You will need a Dual Beam capable FF to use one of these ducers.
Power - 600W vs 1kW
- 600W - these ducers are most common for boats under 25' and boats that intend to fish inshore in water less than 250' deep. Effective usable range is approx 900'.
- 1kW (1000W) - these ducers are most common for offshore fisherman and for coastal bottom fisherman. Approx range is 2000'
Tilted Element - Whats this mean?
- In about 2006 Airmar came out with some super cool thru-hull transducers that have owned the market since release. These ducers are flush mount and are meant to be mounted on one side or the other of the center of the boat. The ceramic element inside is actually tilted to compensate for the deadrise of the boat. These ducers do not require a fairing block and are very easy to mount. They are offered in 600W and 1kW. They come in 12 degree or 20 degree tilt. If your deadrise is higher than 15 degrees then get the 20 degree ducer, if 15 or less then get the 12 degree version. Easy.
- If your boat is bottom painted and you leave it in the water you will alo need to paint your transducer. It's important to make sure you use a water-based anti-fouling paint. We sell it in small spray cans.
In Hull Ducers - How to get water temp?
- In Hull ducers are suitable for many boats, but fisherman still want water temp. There are 2 ways to go about getting temp. One is a transom mount temp sensor and the other is thru-hull. Some electronics manufacturers like Garmin and Raymarine offer Y adapter with temp sensors to make adding temp a breeze. With other brands you can actually use a NMEA temp sensor. These come in two varieties - smart and analog. Analog sensors require a doo-dad to convert the analog signal to NMEA while smart sensors do this conversion internally. With either variety they will ultimately terminate at your electronics display connecting to the NMEA0183 input. NMEA2000 temp sensors are starting to hit the market too. Of course these will plug right into your NMEA2000 network (see our NMEA2000 Guide).
**Since this article was written in 2012 a lot has changed with technology, however the principles discussed above remain the same. Please call us to learn about the new CHIRP transducers.