[Fr. Frank]

Originally Posted by jsylvester08

Does anyone have any ideas or know a specific location I can mount it to read underway. I have an 86’ 20SF.

I believe I can help.

It depends on the type of transducer, first of all. Most "professionals" mount the transducer improperly, whether its a transom mount, thru-hull or in-hull 'ducer. That's most "professionals" are boat yard workers or mechanics or just riggers who've never taken the time to troubleshoot fish-finder problems.

The emitting surface needs to be completely below the hull of the boat Both Sides! Modern SideScan/Side-Vu/Side View transducers have an 84-87 degree emitter angle. That gives a total emitter transmission angle of 168-174 degrees. If the inboard side of your transducer has either the keel-line of your hull in the way OR the inboard side is above the hull bottom, its not going to work. In one case the hull is blocking part of the emission and in the other, it's emitting into the air whenever you're on plane or nearly so. No Bueno.

In the case of thru-hull transducers, you need a PAIR of transducers to take advantage of SideScan/Side-Vu/Side View technologies if you have a deep-V hull, or a proper kelson or keel.

In the case of transom-mounted 'ducers, it must be mounted away from any white-water or turbulence stream. That means you need the length of the transducer's aft protrusion in side clearance clearance from the path of any lifting corners, strakes, or chines. For SeaCrafts, this means the center planing surface is almost always the best place, and the center of the planing surface is the best. Also, you need to stay the equivalent of the radius of the prop away from the prop diameter to avoid the 'ducer introducing ventilation to your prop.

I have a Navico Simrad "Active Imaging 3in1" transducer on my 18' Superfisherman and I can hold steady SideScan imaging up to 27 knots in calm water. Above that speed I start to lose clarity. It's great for hunting for the lone rock pile to find snapper or grouper or AJ's.

I'll try to find a couple of old pictures of the proper mounting of a transducer.