Tuesday, August 9, 2011

DIY Kayak Transducer Arm for the 2012 Wilderness Systems Ride 135

I have received a lot of questions on how I fabricated the rear transducer arm for my 2012 Ride 135.  There are a few elements I may update with this setup in the future, but I really like the way it works as-is.    In the past I have used transducer arms that hang over the side of the kayak (like this DIY removable fish finder project) or installed the transducer so that it fires through the hull.  This new setup accomplishes a couple things:  1) water temperature is accurately measured and 2) the transducer is protected, out of the way and creates minimal drag.  Having the ability to rotate it up and out of the way also makes things easy during transport.

Shopping list:

Poly Cutting Board (Walmart, Target, etc.)

Aluminum Flat 1/8 x 3/4 x 3'  (LINK)

1 Rubber Stopper 3/4 x 9/16 x 1 Lowes Item # 139548 (LINK)

Package of ¼-20 x ¾ SS Oval Head Machine Screws for mounting assembly to existing rudder holes – Lowes Item #136337  (LINK)

Package of 8-32 x 2 SS machine screws Lowes Item # 136468 (LINK)

Package of 8-32 Stainless Steel Forged Wing Nuts Lowes Item # 136212  (LINK)

Zip Ties, Marine Goop

(Note:  Some of the Lowe's links may display "product not available online" but they are regularly stocked in all the local stores)

Step 1
Cut out a 4” X 1.5” rectangle from the poly cutting board.   As pictured, cut an additional slot in the center of the 1.5” side at the ¾” mark that is 2.5” in length as depicted in the photos.  Make sure the slit is wide enough to accommodate the width of the aluminum flat stock.   

Step 2
While wearing thick leather work gloves, use a heat gun to bring the poly rectangle up to temperature, focusing on the slotted end.  Once the poly rectangle is pliable, secure it in a vice and bend by hand until it looks similar to the one in the pictures.  Hold it in the curved position until the poly cools.

Step 3
Using a vice, make a 90 degree bend in the aluminum stock that will accommodate a proper mounting point for your transducer.  Cut the stock to 10” in length above this bend. 

Step 4
Line up the poly rectangle on the stern of the kayak where the preinstalled rudder mounting holes are located.  Mark and drill the holes in the poly rectangle and use the ¾” SS Oval head bolts to temporarily mount the unit to the kayak as pictured.  Slide the aluminum flat stock arm into the slit in the poly and position the arm so that it is vertical.  Note that the aluminum arm will rest against the 2 mounting bolts that hold the poly to the kayak. 

Mark and drill a hole starting on one side of the poly cutting board, continuing through the aluminum arm and back out the other side of the cutting board that will accept the 8-32 x 2 SS machine screw.   Slide the bolt into position and tighten the wing nut, creating a pivot point for the arm.  Clean up the aluminum arm with a grinder making sure to round off all sharp edges.

Step 5
Remove the factory installed drain plug from the rear portion of the kayak and feed the transducer cable into the hull.  Drill a hole through the rubber stopper that is the same size as the transducer cable.  Using a razor blade, cut a slit into the stopper until it meets the hole that was just drilled.  This will allow the cable to slide into the stopper as pictured.   Place a liberal amount of Marine Goop on the stopper, transducer cable and drain hole and slide the stopper snugly into place.  Allow it to dry and ensure that you have a watertight and secure seal.

Step 6
Mount the transducer to the arm and secure the cable with zip ties or similar method.  I used some of the hardware that came with my fish finder to route the cable from the rubber stopper to the aluminum arm.  That’s pretty much it!- Paul


  1. That's neat, but running the transducer behind you is useless

  2. You need to have a working understanding on how sonar/depth finders work before posting a comment with absolutely no factual merit. Here's a brief overview - http://www.fishfinder-store.com/howfifiwo.html

  3. Good morning. The previous commenter's link gives a good example of how sonar works. Most boats in general have the transducer mounted on the stern. Since the sonar signal "fans out" in a conical shape, the transducer can be mounted pretty much anywhere on the kayak - especially since it is a boat that is less than 14' in total length. While in the past I have mounted the transducer to shoot through the hull, I really like this method better b/c I can take advantage of the temperature gauge

  4. Would this work on a 2009 model Ride 135? Don't know if the factory plug is a new feature.

  5. I believe the 2009 Ride 135 has the drain plug on the stern as well except it is on the opposite side. Here is a link to a random 2008 Ride 135 (same design) - you can see the drain plug in the first picture - http://forum.gon.com/showthread.php?t=402185

  6. Did you just drill into the kayak and use a grommet to plug the hole at the base of the fishfinder?

  7. @ anonymous - details on the rest of the fish finder install is here


  8. How did you get such clean cuts on that aluminum? Did you do it by hand or use a band saw? All I have available is a jig saw and thought that might make a mess. Getting ready to head to Lowes :)


    1. Use a hacksaw then a small fine flat file.

  9. To get the straight cut, I used a metal cut off tool that uses abrasive disks. It works like an electric miter saw because the disk is fixed on an arm but the circular "blade" has no teeth. You could use a jig saw, but use a blade that has a lot of teeth similar to a hacksaw blade...the more teeth the cleaner and more precise it will be. Also, make sure you have the aluminum clamped down on either side of the cut line to prevent it from moving while you are cutting it with the jig saw. Finish the cut edge off with some sandpaper (120-150 grit) and you can get a clean edge.

  10. Thanks...working on the arm now. Should the transducer be perfectly level with the bottom of the boat or is a little difference OK? Should the arm be resting against the screws when hanging straight down, or do you just tighten the screw when it is in the correct position?

    Thanks for the help!

  11. Hey Seth, it doesn't have to be "perfectly" level, but you don't want it angled too much either. The aluminum arm will rest against the mounting screws that secure the cutting board to the back of the kayak. If for some reason yours is not level because of the mounting screws, put more of a bend in the cutting board piece until you get to the angle you need to make the transducer level. When it is in the "down" position, I just tighten up the wing nut to keep it in place.

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  13. Well...I think I did it! Not sure if I have the transducer in a good position as it is pretty close to the bottom of the yak. I've never used a FF so I didn't know if the kayak would interfere with the transducer signal. Do you think I should lower it or raise it? Here is an image (http://dl.dropbox.com/u/1670410/transducer-arm.jpg)

    Thanks for all the help

  14. The arm assembly looks good Seth. From the picture it looks like the transducer is pointing backwards. You can easily fix it by reinstalling the transducer on the bottom bracket to make it face forward or slide out the "hinge bolt" at the top, turn the arm around and reinstall the bolt. Nice job and this should work nicely for you...I have been very pleased with this setup. You can bring it up a hair if you would like after you install it facing forward. My transducer rides about a 1/4" -1/2" above the keel line so in the event I hit a rock or something moving forward, the keel takes the direct blow before the transducer. Even if you leave it as-is, the arm will "kick up" out of the way if it hits something.

  15. Nice work! I just sold my Prowler last night and will be getting either the Ride 135 or Commander 140. Might just have to try this out.

  16. I don't have any of the tools needed to make this. Any chance you would be willing to accept payment to make one for me?

    1. Hey David, if I had more time and some extra parts laying around, I would definitely do it for you. Unfortunately my new job takes up a lot of my time so it really isn't feasible right now. Sorry man.

  17. The nut on my transducer wire won't fit through the drain hole. What do you think about removing it and just using the friction of the plug to keep it in the depthfinder?