Trouble Free Sonar
Installation

A sonar unit owner called the manufacturer's customer service to lodge a complaint. "I'm getting a strong flash at the zero mark," he said. "But I'm not getting a bottom reading next to the bank." "It sounds like a transducer problem," the service rep told him. "How was your transducer installed?" Dead silence for a few seconds. "My what?" the angler asked. His problem was improper installation, not an operating one, which, according to industry spokesmen, is typical of many complaints. The odds for a trouble-free installation are in your favor if a professional does it. Even he, however, doesn't always score 100 percent on the first try. Here are tips to help you install your new unit, or to ensure that someone else installed the one on your boat correctly.

Where To Mount It: Holes are expensive to move. Before a drill takes its first bite, make sure the holes are where you want them. Choose a flat surface where the unit is both easy to see and convenient to reach. Set the unit on the spot with its bracket and cables attached. Touch the unit's controls and look at its display from typical driving and fishing positions. If you will be using the same unit when behind the console driving and when fishing up front, consider installing a swivel mount. Make sure there is room for the cables and ample clearance from windshields and other objects when the unit is tilted or swiveled.
Mounting The Unit: With the sonar unit in position, draw a circle inside each bracket-mounting hole with a felt tip pen or soft pencil. A good tip is, drilling the first hole, then mounting the bracket or swivel base with one bolt or screw. Use the bracket as a guide to drill the rest of the holes. Always check behind the surface that you're about to drill through to prevent damage to important items like wiring, plumbing or steering cables. It is preferred my many to use bolts, washers and lock nuts to self-tapping screws when you can get to the back of the mounting surface, and always use stainless steel hardware. If screws are used in fiberglass, select a drill bit that makes a hole one bit-size smaller than one the screw will drop into. Go two bit-sizes smaller for aluminum. Try different drill bits on a piece of scrap wood to determine the right hole size. Tighten each screw slowly, turning it clockwise a half-turn, then backing it out a quarter-turn. This cuts threads in the fiberglass without chipping the gel coat. If the fiberglass or aluminum surface is thin enough to need strengthening, cut a scrap of wood to fit behind it for backing. Check your owner's manual for the hole size necessary for your cable plug connections or experiment on another piece of scrap wood. Make sure you can pass the second plug through the hole when the wire from the first plug is in place. Locate the hole as close to the bracket as possible.
Installing The Power Cable: You can route the power cable supplied with the sonar unit as far toward the engine starting battery as possible, then splice it to an extension wire at least one size larger in diameter (18-gauge minimum) to reach the battery. Soldering and taping makes a better connection than crimp-on splices. It is a good idea to install an in-line fuse at the battery. Check the owner's manual for the correct fuse rating and make sure to keep spare fuses on board. Some boats have built-in tubes for their wiring harnesses, and stringing an additional wire through them can be nearly impossible. Connecting to existing power and ground terminals is then necessary. Extra fuse block terminals, unused accessory switches, or a 12-volt positive connection on the back of your instrument panel can be used for power. Choose a lightly loaded circuit and avoid connecting to the same point where your tachometer, CB or marine radio is wired. Make sure the power source is fused. Check to see that it's hot with the ignition key on or off. A common ground connection is usually a terminal holding several black wire. Use a test light or multimeter to confirm that it's a ground.
Routing Cables: Manufacturers recommend routing cables away from other wiring, but that isn't always necessary, or even possible. Luckily, wire-to-wire power line interference isn't as common as it used to be. Route cables away from high-risk areas. Don't run them where tackle boxes, steering components, fuel or oil tanks, or batteries can shift and damage them.
Installing The Transducer: A transducer must maintain solid contact with the water at all boat speeds and during any maneuver. If the transducer breaks contact with the water, the sonar unit is blinded and appears to go crazy as it searches for the bottom. The transducer must point straight down or slightly ahead while the boat is moving in order to show you what's beneath your boat. It would take an entire article to cover the proper way to install a puck transducer inside your bilge area to shoot through the hull. It is recommended that inside installations be left to professional installers. Trolling motor transducer mounting is straightforward. Attach a transducer designed for the purpose to the bottom of the trolling motor's lower unit. Use nylon wire bundling straps or a metal hose clamp. Then, unless the design of your motor prohibits it, use nylon wire straps about every 6 inches to anchor the transducer cable to the trolling motor shaft. An un-anchored cable can snag weeds and may be scissored by the trolling motor bracket during stowing. The most common do-it-yourself installation is to mount the transducer on the outside of the transom. The transducer must be mounted even with the bottom of the hull or slightly below it. It must also be mounted where the water flow across it is free of turbulence or streams of air bubbles. Because of the direction your propeller turns, the right side of the transom is less prone to cavitational interference. The ideal location is from 12 to 18 inches to the right of your engine. That's far enough away to avoid picking up noise from the engine yet close enough to the boat's center line to stay in the water during turns. To find the right spot, take a crayon, a buddy and your boat to the lake. Put on a life jacket and lean over the back of the boat carefully while your buddy drives at planing speed. Look for a place on the transom where the water coming out from under the hull is smooth and dark; avoid areas where light-colored water streams out. Light-colored water usually indicates air bubble streams. Mark the best looking areas with your crayon. Load the boat on your trailer and examine the areas you marked. Avoid hull curves or lifting strakes and make sure that a transducer can't interfere with bunkers or rollers on the trailer. Mark your best spot. Assemble your transducer and bracket and hold it against the transom at your selected spot. Align the transducer according to the installation instructions in your owner's manual. The transducer bracket has slots instead of holes to give you room for adjustment. Mark the mounting slot positions. You are more likely to need to lower the transducer than to raise it, so drill your first hole about three-quarters of the way down from the top of one of your slot marks. Run the drill at slow speed and stop drilling when your hole depth equals the length of your mounting screw or when you get through the fiberglass and hit wood. Mount the bracket in place with the first screw, driving the screw slowly as before. Snug the screw enough to hold the bracket in place. With the bracket adjusted, use it as a guide for the next hole. Drill it about three-quarters of the way down from the top of the slot. Carefully install a screw and snug it. Double check the transducer's alignment and you're ready to seal the holes. With all of the screws snug, remove one of them and put a blob of sealant on the threads. Force some sealant into the hole in the transom, then run the screw back in and tighten it. Seal the other screws the same way one at a time. Cover the screw heads with a blob of sealant. Even stainless steel will corrode with time if left exposed, and this ensures that you'll have a clean socket for your screwdriver to grip should the screw ever need to be removed. Most tubes of silicone sealer carry a warning that the product is not intended for use below the water line. Appropriate sealants are available from marine dealers.
Side-Scanning Transducers: Side-scanning sonar units, like the Bottom Line Scout and Stalker Sidefinders and the Eagle Magna II with ScanPac option, have different requirements for transducer installation than vertical-scanning units. Transom installations restrict the use of a side-scanning unit to the point where I wouldn't consider one. The most popular installation is to strap the transducer to the side of the trolling motor. The unit can then scan as the trolling motor is turned. This installation is better, but still not ideal. If you put the transducer on the right side of your trolling motor, it only scans the shoreline if it's to the right of your boat. If the shoreline is on your left, you have to stop the trolling motor and turn it 180 degrees each time you want to scan the bank. That could get exciting if you were fishing a windswept riprap bank and had to run the trolling motor constantly to stay off the rocks. Using an accessory bracket like Tite-Lok's directional transducer holder makes the most sense to me. The bracket lets you side-scan in any direction, regardless of boat or trolling motor position. The bracket's upper steering arm is at a right-angle to the shaft and lines up with the transducer. This lets you aim to transducer with your hand or foot, and indicates which direction to cast when a fish is spotted. Mounting location and angle are also critical in side-scanning installations. The top of the transducer must be about 8 inches below the water's surface, the transducer must be angled four or five degrees below horizontal for all-around use, and closer to horizontal in water less than 6 feet deep (the Tite-Lok bracket also allows quick angle adjustment). It is strongly recommend spending a day on the lake with your correctly installed new sonar unit without fishing. Practice using the unit's features with the owner's manual in your lap and make any final transducer angle adjustments.
After that, the fish will just have to take their chances.
Sonar Unit Troubleshooting
Interference must be identified as electrical or acoustical "noise" before you can eliminate it. Electrical interference comes through the wiring from the engine's electrical accessories, while acoustical noise comes through the transducer. Here are some common problems and solutions:
Problem: Interference gets worse when engine is revved in neutral.
To Fix: Route sonar unit cables away from engine wiring harness. Check to see that engine has functional noise-suppression spark plug wires.
Problem: Interference gets worse when accessories are running.
To Fix: Run accessories one at a time to identify the trouble maker. Route sonar unit cables away from that accessory and its wiring.
Problem: Interference does NOT get worse when engine is revved in neutral, but DOES get worse as boat speed increases.
To Fix: Try adjusting the transducer's angle, dropping its rear end slightly. If trouble persists, move transducer to a better position.
Problem: Unit stops reading bottom at high speeds, during turns, or when boat is loaded heavier on the left or right side.
To Fix: Adjust transducer's side-to-side angle to be parallel with boat's cockpit floor and angle rear of transducer down slightly. If problem persists, move transducer slightly lower in water while maintaining proper angles, or move it closer to the center line of the boat. Balance load in boat to allow a level ride.