Transom Mount Transducer Location Help

K-Dogg

Almost A Member
Jun 11, 2017
111
172
Oregon
Name
Ken
Boat
1970 Skipjack 20 Open
I was thinking about ordering a Sternmate, Transom Pad, SternSaver type (poly plastic) transducer pad (mounting block) using 3M 5200 Fast Cure rather than sending (3) screws into my transom. I know, never use 5200 on the boat, but I need the heavy duty adhesive to essentially permanently glue the transom (saver) pad and avoid using screws.

That said, I’m unsure of the mounting location? I have the Garmin GT51-TM transom mount that is three in one (down, clear and side views). Garmin suggests a starboard location and away from lifting strakes and aft of anything that can cause bubbles (i.e. in-hull transducers, high speed water pickups, etc.). Thankfully I don’t have any preexisting device holes to worry about with the installation that could cause interference and dirty the water flow forward of the transducer.

I think the Bennett SLT (self leveling trim) tabs which stay down at low speeds may slightly interfere with the side imaging technology if I mount the transducer in the red box (picture) below and that a better mount location would be between the garboard drain plugs?

The benefit of mounting the transducer at the keel would be better side images (I think/hope) due to less interference by the tabs -AND- the transducer would be further away from a trailer bunk that could damage the transducer when loading and unloading the boat. The downside is that the 9” clown shoe could create dirty water for my propeller on my main motor causing cavitation at higher speeds.

My gut says running the cable straight down the edge of the starboard side of the offshore bracket which puts me +/- 2” inside the the lifting strake and in clean(er) water with less disruption and it would comply with the Garmin installation recommendations as well.

If I end up mounting the transducer between the garboard plugs at the keel it opens up a problem of routing the cable around the Armstrong Nautical offshore bracket. I hear that they make sticky pad cable ties that eliminate the need to drill screw holes into the transom which is my goal too.

What does the BD community think would be best on my 1970 Skipjack 20 Open?

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sickcat

Silverback
Aug 5, 2003
3,784
1,887
64
LA
Name
Kerry
Boat
Yellow spot
Red box in your first picture. Trim tab isn't going to interfere with side imaging.
+1 on option #1.

Though you have more room than most I still don't like things directly in front of the engine.

The reason for the starboard side is prop rotation. Strbd side prop is pushing down and away from the xducer, port side would be up and at it.
 
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Unassailable

Professional Amateur
Aug 26, 2009
1,364
758
San Diego
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John B
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BW
Yep, #1 is the best spot. Good news is with the setback from the bracket, you should have significantly less (if any) interference from the motor.

Sternsaver is a wise choice since all the manufacturers appear to only make mounts that you cannot adjust without loosening the screws. You do not want to use 5200 and stern saver comes with its own epoxy. Just buy slightly shorter screws so you do not go past the starboard. Then you can adjust incrementally left/right, up/down.

Also, use two holes to hold the 'ducer until you find the right spot. Then drill and attach the third hole.
 
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Mangimi

Newbie
Mar 7, 2021
3
2
32
Scandinavia
Name
Karl Koch
Boat
Nauti Boy
I'd put it as close as possible right of the drain plug. On my boat it was analog to the right of the red box you have drawn and I wasn't able to get signal on plane. Moving the transducer towards the outboard helped a lot and kept the signal stable up to 25mph. However, I wouldn't glue the backing plate in place. I'd just screw the transducer down and reseal the screws every (other)year with fresh sealant. Transducers are expensive and I wouldn't want to ever worry of it coming off.

transducer.png
 
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K-Dogg

Almost A Member
Jun 11, 2017
111
172
Oregon
Name
Ken
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1970 Skipjack 20 Open
Here is an update on the transom pad and transducer mount location. I’m hoping that we’re not too close to the trailer bunk, that the high speed spray shield prevents a rooster tail spray when I get the boat back on the water and that I can travel 25 to 30 MPH without loosing bottom signal?

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sebastian

Newbie
Oct 1, 2005
67
17
53
Carlsbad
Name
Sebastian
Boat
Ocean Seafari - 17 Whaler
Just curious - how did you attach- 5200 only? I am currently using a stern saver.
 
K-Dogg
K-Dogg
If you look closely you’ll see (2) stainless steel screws on the high-density polyethylene (starboard) 3/4” plate that was pre-drilled. The plate holds up to 4 accessories, allows unrestricted placement of transducers and came with (2) stainless steel screws. Bass Pro Shops calls the plate a “Transducer Mounting Plate” and is $19.99
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