Advice on How to mount Side / Down Scan Transducer on Aluminum Boat

[fundseeker]

Hi, I'm looking for your thoughts on the following method to install a large transducer on a transom? I am considering bolting a piece of 1" x 6" Trex composite deck board onto my 16Ft Misty River aluminum transom on which I will mount the 11" long Lowrance Elite Ti transducer . ( This will allow me to move it around , drilling mounting holes ,to find the sweet spot with the least water surface turbulence and best signal ) I am considering trying to smooth the double row of rivets on the trailing edge of the hull beneath the transom with JB Weld epoxy , and dropping the planed flat edge of the Trex board so that it is level with the bottom of the boat thus creating a smooth trailing edge with hopefully less water /air turbulence and a better sonar signal.The 1 " thick Trex is much denser than cutting board like material. The boat sits on a trailer most nights. I don't believe the Trex absorbs an appreciable amount of moisture. I figured I would use 6 - S.S. bolts and seal the holes and the back of the board with Marine silicone. The 2 lb transducer is supported by a stainless steel frame but could apply considerable force on the 2- 1" screws which will secure it to the Trex board.I am also considering mounting it on the port ( left) side even though some say there may be prop wash with bubbles at low speed on that side causing poor sonar signal when using the outboard motor) I have read that the hinging bolts securing the transducer steel support to the slotted steel transom mount have a history of loosening on this model , adversely affecting the alignment and direction of the sonar signal and quality of the on screen display. I was told to obtain some specialized star shaped stainless lock washers to stop that loosening from occurring. I would appreciate any thoughts or experiences you might have with transom mounting these large transducers . Thanks!

[Old Ironmaker]

Dave fro Whitehorse just mounted 2 of these big transducers. I didn't read how he did it but whatever he does it is guaranteed it is the best method. You mention using 6 stainless bolts to secure the Trex board, I like the Trex idea over the $$$ store cutting board stuff. If you mean to say you are going to bolt it completely through the transom to the interior side I may not normally agree. But looking at how extremely large and expensive they are I just might as long it isn't close to where the bottom of the transom meets the hull. Whatever method you do go with I highly recommend 3M 4200 or 3M 5200 silicone for all Marine silicone adhesive applications. They use the stuff on Space Capsules splashed into the Ocean. If you never want to remove the screws go with the 5200, otherwise the 4200 will be the silicone/adhesive you want. Better adhesion than some brands of 2 part epoxy. Like you said before setting it for the final time use a sacrificial piece of Trex, once you have the thing where you want it after making some runs and tests on the water then mount a new board and install for the final time. I don't think the rivets will interfere, you can always back fill the gap with a bead of 3M 4200. I see a rooster tail in your future if you don't get it just right.

 

2 pounds, man that is one big, heavy transducer. Take into consideration where it sits when loading/unloading on the trailer. Not as critical as a thru the hull design. I am thinking there is a lot of juice running through the cable. I might take the time to insulate the cable if running near any other electrical/electronic cables and they usually are.

Edited July 15, 2017 by Old Ironmaker

[Garnet]

Think I would leave the JB Weld idea on hold. Structure scan is at 3-4 mph so turbulence is not that big of deal.

 

I would look around Radio World site, Find Larwen Wensal installation instructions.

 

Running cables together or balling excess and taping are all bad. Your unit should be hard wired to starting battery.

 

To do a great job likely $200 for stainless buse , 6 gauge proper connectors.

 

I got all this stuff from Whitby marine supply. You can't believe what he has. Not cheap but good stuff.

[porkpie]

If you are talking about using 6 stainless bolts to mount a piece of trex to the back of your boat that is way overkill. My old Lund had a piece of starboard affixed to the back of the boat with nothing but 3m 5200. It's still there 12 years later and my buddy has a humminbird side imaging transducer hanging from it. Currently my Starcraft has a piece of starboard affixed to the boat with 3m 5200 and 2 stainless screws through the transom to hold it in place. Attached to that are a raymarine down imaging transducer and a lowrance totalscan transducer. 6 bolts running through your transom is 4 more than you need. I did use 4 short screws to mount the total scan transducer to the starboard because as you say it is kind of heavy. My advice, don't overthink it or overdo it. As for the trex vs starboard, the way I look at it is that I'm only doing this once every so often as I don't get a boat every year, so I might as well stick with the tried and true. Good luck.

[Pikeslayer]

This is your solution:

http://www.smithmountainstriperclub.com/the-boathouse/making-a-transducer-mounting-plate

 

Spincast passed this off to me a while ago. Easy, cost efficient & no holes in your transom.

[fundseeker]

Thanks very much for your replies and advice guys. Your ideas will assist me with my method to install the transducer. Can't wait to get the finder installed and go fishing again.

[Old Ironmaker]

This is your solution:

http://www.smithmountainstriperclub.com/the-boathouse/making-a-transducer-mounting-plate

 

Spincast passed this off to me a while ago. Easy, cost efficient & no holes in your transom.

Great procedure. I don't see anything coming off that boat anytime soon.

[Garnet]

See those tie wraps in the last pic. This could be a problem.

 

The side scan and the skimmer are lowrance and that 3 rd is likely Hummingbird the tie wrap bundles these different frequency together.

 

Just something to think about when running wires. If necessary I've used up a roll of electric tape for added insulation.