Mounting Transom Transducers
Probably the most difficult part of installing a new depth finder on your boat is mounting the transducer and getting it to read clearly while the boat is up on plane. Keep in mind, any transducer that can read when the boat is still can read when the boat is moving, provided it is mounted correctly.
The reason a poorly mounted transducer loses its reading at higher speeds is because it loses its contact with clear water. In order for it to read clearly it must maintain a smooth water flow across the face. If turbulence develops directly in front of the transducer you will lose the reading. This turbulence is usually caused by ribs or strakes under the boat, scratches in the hull, rivets along the transom, or even the transducer itself.
To properly mount a transducer for high speed operation follow these tips:
1. Make sure you have the right kind of transducer. A transom mount high speed transducer has a point on one end and a flat edge on the other. A round transducer ( Puck Style ) will work for high speed, but must be mounted inside the boat. This is a tricky installation that will be covered in the future.
2. Find a good spot to mount it to. Look under the boat and notice any problem areas that may cause turbulence. Try to keep it close to the center of the transom, within 18″, but make sure it will not interfere with the operation of your engine.
3. Use a mounting plate. This can be a piece of wood or a polymer plate made just for this purpose. Most people will simply mount the transducer direct to the transom, which is OK until you find that it needs to be moved to get a better reading. Mount the plate so the bottom edge is even with, but not below, the bottom of the transom.
4. Attach the mounting bracket to the transducer first. Slide it all the way up in the bracket. Hold the assembly up to the boat in the location you think will be the best. Position it so that the pointed end is facing forward and is even with the bottom most edge of the transom. Mark the holes that need to be drilled at the bottom of the adjustment slots on the bracket. Drill out the holes and attach the assembly.
5. Once the transducer is mounted, adjust it in the bracket so that the back edge is slightly lower that the front, pointed, end. This angle depends on how your boat rides in the water. If the bow generally rides higher than the transom this angle will be less than a boat that rides level.
6. Tighten all the screws and run the cable up to the depth finder. Make sure the cable is restrained and not allowed to flop around in the wind as this will cause wire breakage.
Now it’s time to take test drive and see how good a job you did. Make sure your boat is weighted just as it would be if you were going out for real. The weight has a lot to do with the way the boat rides and will have a big impact on the way your transducer needs to be positioned.
Run across the water and note how the unit reads at different speeds. If you lose the reading, notice how the boat is riding at that speed so you can adjust the transducer angle accordingly. If you can’t read at all keep lowering the transducer until you can. Sometimes the transducer will have to be low enough to cause a pretty good rooster tail.
It may take several trips across the water to get the best results. You may even need to remount the transducer to get a consistent reading. It will all pay off in the end, however. You will find fish and structure with the Vexilar flasher that even the most expensive LCD’s will never see.