CONTINUOUSWAVE

For a 1978 Outrage 21 what is the best transom location to mount a TotalScan Transducer?

The current location [of the TotalScan SONAR transducer results in the SONAR] only holding the bottom echo at low speeds of less than 10-nautical-miles-per-hour, even at depths as shallow as 50-feet.

Performance possibly could be improved with the existing gear if moved a little higher in Y direction to reduce cavitation and angled up to account for bow lift while planing, but I haven't done much tuning with the current setup.

Notice there are four sets of older hole from previous owners over the years, and they vary widely across starboard side of the transom.

Has anyone been able to dial-in transducer positioning from keel line on the c.1978 Outrage 20 [21] hull?

Is the current position of 11.5 inches from keel optimal?

This particular boat may be a little complicated by the powerlift the engine is mounted to, although the extra clearance may actually enable me to go a little closer to keel line—if anyone thinks that would help minimize any effect of the hull strakes might have on current position and help provide clearance for the side scan feature of the transducer to the port side.

Appreciate any wisdom that can be offered.

And thanks to you all, especially Jim, for the great resource this site is.
-Adam



https://photos.app.goo.gl/msdHuvaJ4LqKwj2G8

https://photos.app.goo.gl/sa6MFvMA7AG13h1V9

https://photos.app.goo.gl/T5ZhXVrt4gE2KYHq7

I don’t have any first-hand experience with the Outrage 21 hull and SONAR transducer location, but I have experienced the same problem—loss of bottom echo at higher boat speeds—with other boats and other transducers. The remedy has always been to move the transducer closer to the keel centerline, coupled with adjustment of the immersion depth of the transducer below the hull.

Because the TotalScan transducer is also a side-scan, it will likely need to be mounted closer to the keel centerline to avoid being shadowed by the hull. I would defer to the Navico instructions for mounting. But because the Outrage 21 hull is such a round bottom and relatively flat, being right on keel centerline probably won’t be necessary.

And I understand your concern about having already too many old mounting holes in the transom. I have the same situation with just two leftover sets of holes.

I hope another participant can give you better advice.