# Transducer location with trim tabs



## Subtraction (Dec 21, 2021)

Removed a Garmin gt54 transducer to put on trim tabs. I’d like to put it back on but space is extremely limited. See pictures below of being loosely mocked up.

Between the tabs I’ll be interrupting the props path. Potentially causing performance issues.

On the outside of the tab it looks silly, damage seems more likely, bottom of transducer will be slightly above trim tabs and may cause interference?

Had an airmar b150 thru hull on order but want the additional features the gt54. Any suggestions? Thank you!


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## Smackdaddy53 (Dec 31, 2012)

Do you need a transducer?


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## Subtraction (Dec 21, 2021)

Yes unfortunately. Tried to go without but it’s a handicap I’d like to not have. Fish mostly Lake Lanier in Georgia it’s very deep and I miss traditional sonar and side scan capabilities.


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## Rookiemistake (Jan 30, 2013)

Shoot thru


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## lemaymiami (Feb 9, 2007)

If you read the literature that comes with most trim tab kits - they want you to install that transducer where it gets clean water off of your hull bottom... Since it only skims the surface of the water coming off of your transom I doubt it would cause the slightest problem for your motor.... I'd have a buddy get your hull up on plane then from the stern of your boat look down to where your trim tab is and watch to see exactly how far from it you have to be to have that transducer in "clean water"... Mark it with a Sharpie - then it's back off the water for the install... 

As you install it run a straight edge along the bottom of your hull extending it past the transom a few inches to see exactly where your water will be flowing off the stern of your hull - then set that transducer so that it's about 1/4" lower to get good readings while you're running... and you should be good to go... 

Hope this helps - "Aren't boats fun?"


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## Subtraction (Dec 21, 2021)

lemaymiami said:


> If you read the literature that comes with most trim tab kits - they want you to install that transducer where it gets clean water off of your hull bottom... Since it only skims the surface of the water coming off of your transom I doubt it would cause the slightest problem for your motor.... I'd have a buddy get your hull up on plane then from the stern of your boat look down to where your trim tab is and watch to see exactly how far from it you have to be to have that transducer in "clean water"... Mark it with a Sharpie - then it's back off the water for the install...
> 
> As you install it run a straight edge along the bottom of your hull extending it past the transom a few inches to see exactly where your water will be flowing off the stern of your hull - then set that transducer so that it's about 1/4" lower to get good readings while you're running... and you should be good to go...
> 
> Hope this helps - "Aren't boats fun?"


Thank you! I had it mounted previously roughly centered where the trim tabs now are. I did use the straight edge off the bottom of the hull.

That’s a good idea if my friend is at the lake this weekend I’ll see if he can hop on board and do that for me!


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## Finsleft258 (Oct 7, 2018)

Rookiemistake said:


> Shoot thru


Side scan won't work going through. Just saving you a headache for the next install.


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## lemaymiami (Feb 9, 2007)

Me, I'm still running a long out of date simple Lowrance X65 unit - but will upgrade on my next motor replacement (since I'm switching motor brands I'll also need a complete re-do of my console.... and will take the opportunity to actually upgrade to a modern chartplotter, etc... ). Long winded way of saying that I'm looking forward to a side scanning capability as well... A year from now I'll be a beginner again and looking for advice on my install like everyone else...


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## Subtraction (Dec 21, 2021)

lemaymiami said:


> Me, I'm still running a long out of date simple Lowrance X65 unit - but will upgrade on my next motor replacement (since I'm switching motor brands I'll also need a complete re-do of my console.... and will take the opportunity to actually upgrade to a modern chartplotter, etc... ). Long winded way of saying that I'm looking forward to a side scanning capability as well... A year from now I'll be a beginner again and looking for advice on my install like everyone else...


As I’d previously mentioned I fish in a deep lake most of the time. Up in the creeks the bank drops off to about 10’ quickly then tapers down to 30-40’. Using side scan down the middle of a creek and finding brush piles or structure is extremely beneficial. You’ll have lots of fun with it when you get around to upgrading!


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## lemaymiami (Feb 9, 2007)

Where I guide most is in the interior of Everglades National Park where there are numerous rivers and creeks that drain out into the coast from fresh to saltwaters... For many years I've used those banks to target fish from small to large and I've been told with the right installation we'll be seeing the fish instead of prospecting for them...


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## Subtraction (Dec 21, 2021)

lemaymiami said:


> Where I guide most is in the interior of Everglades National Park where there are numerous rivers and creeks that drain out into the coast from fresh to saltwaters... For many years I've used those banks to target fish from small to large and I've been told with the right installation we'll be seeing the fish instead of prospecting for them...


I’ve not had the best luck seeing fish with side scan unless they’re bigger and theyre still hard to see with how large an area you’re viewing and the amount of data on screen. Seemed easier on the 12”+ size units but they’re way too expensive for me even if I had a place to mount one of those behemoths.


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## fishnpreacher (Jul 28, 2018)

Take into consideration that your side scan will be compromised somewhat by the foot of the motor, and the closer to the motor, the more compromised it will be. There is a sweet spot for the 'ducer, and unfortunately your trim tab has it covered. The best spot for it is closer to the outboard, but side scan will be off a bit on the left side.


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## Rookiemistake (Jan 30, 2013)

Anyone really use the transducer to find fish inshore?


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## fishnpreacher (Jul 28, 2018)

I fish freshwater lakes mostly, but I have fished around St Simons and Jekyll Island area. Not much use trying to locate fish that shallow with a fish finder. I did use mine to follow depths and contours though.


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## Subtraction (Dec 21, 2021)

fishnpreacher said:


> Take into consideration that your side scan will be compromised somewhat by the foot of the motor, and the closer to the motor, the more compromised it will be. There is a sweet spot for the 'ducer, and unfortunately your trim tab has it covered. The best spot for it is closer to the outboard, but side scan will be off a bit on the left side.


Thanks for the input! Even if Iount the transducer dead center it’s still pretty far away from any part of the outboards lower unit because I have the offset of bobs tilt n’ trim unit plus an additional 2” worth of starboard that I bolted to the bobs unit as a means of thickening that mounting surface so the thumb screws have enough thickness to be tightened.

I wasn’t too worried about actual performance of the transducer in that location because it seems like the “cone” underneath would have a clear unobstructed view all the way around. Maybe that makes sense? My biggest worry was disturbing the water before it got to the propeller and creating cavitation problems. Think I’ll be dealing with both that and funky transducer readings?

thank you!


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## Subtraction (Dec 21, 2021)

With that logic maybe going a more unconventional route and mounting the transducer on the port side where the prop is makings it’s path upward would lead the transducer to interfere less with the outboards performance? But then I’d also imagine the water around the transducer would be more disturbed than if it was on the starboard side and dealing with water on the props downward into the water direction.

Its too bad all the thru hulls capable of side scan look to be massive, require 2 precisely mounted transducers, and are prohibitively expensive.


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## fishnpreacher (Jul 28, 2018)

The Bob's will definitely help, and any other backset will just add to the performance. I wouldn't worry over it causing cavitation too much, main concern would be the effects of the motor on the transducer, and getting a decent reading while under power. I can get a decent enough reading on mine at a little over idle speed, above that gets sketchy. Prop wash affects it some, lower unit blocks some of the signal, etc. My main use is while using the trolling motor and locating structure and schooling fish.


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## Subtraction (Dec 21, 2021)

fishnpreacher said:


> The Bob's will definitely help, and any other backset will just add to the performance. I wouldn't worry over it causing cavitation too much, main concern would be the effects of the motor on the transducer, and getting a decent reading while under power. I can get a decent enough reading on mine at a little over idle speed, above that gets sketchy. Prop wash affects it some, lower unit blocks some of the signal, etc. My main use is while using the trolling motor and locating structure and schooling fish.


Thank you! Sounds about exactly what my use is. If I get good side scan view at/slightly above idle I’ll be happy. When I had it mounted in the optimal position before I installed the trim tabs. Didn’t get good readings at speed then so I’m not hopeful on this location being any better. Who knows it could be incredible. Will update after I get it on the lake this weekend!

Marked it out about half inch away from the trim tab. Drilled out holes and filled with thickened epoxy. Will try and screw it on and wired tomorrow after the epoxy set up.

Thanks everyone


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## Psycho_Killer (May 7, 2011)

Rookiemistake said:


> Anyone really use the transducer to find fish inshore?


most definitely


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## Subtraction (Dec 21, 2021)

Update mounted the gt54 to the left of the trim tab and…. It didn’t work. Chartplotter said something about unrecognizable transducer.

Ordered a gt56 with the Garmin ‘heavy duty’ stainless bracket/mount. Have taken it out a few times now and was pleasantly surprised by the performance.

Accurate depth readings at wot, side scan works incredibly well, traditional sonar is very accurate, and it seemed to cause no noticeable performance problems!


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## lemaymiami (Feb 9, 2007)

Cool, thanks for the feedback... I've found the folks at Garmin are well informed and always willing to help someone sort out a problem... Even, if sometimes I've been told that my device was not capable of what I was hoping for... What sounder (or chartplotter) did you get?


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## Subtraction (Dec 21, 2021)

lemaymiami said:


> Cool, thanks for the feedback... I've found the folks at Garmin are well informed and always willing to help someone sort out a problem... Even, if sometimes I've been told that my device was not capable of what I was hoping for... What sounder (or chartplotter) did you get?


I’ve got the gpsmap 943xsv. Had a Lowrance hds live 7 on my kayak before I got the skiff and planned to use that but was never able to get good traditional sonar images- which I use a lot drop shotting for spotted bass. The garmin gt56 transducer stomps the Lowrance 3 in 1 in my experience.


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## fishnpreacher (Jul 28, 2018)

Looks like you've got it done right. I'm still learning the side scan and bottom scan, I'm overlooking a lot of fish that aren't just blatantly obvious. But I'm learning! You can teach an ol' Dawg new tricks.


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