Well, the new ladder is mounted and working very well, so its time to plan the next upgrade. It took awhile to get the pictures.The transomThe part of the dash that I am hoping to mount the dial.
My hummingbird dash mount depth finder's transducer is mounted on the outside of the bracket on the back of my pontoon as seen in this photo. I used a $5.00 item from Home Depot to mount the transducer to the scupper hole of my mariner.
There is a plastic "T" with a circle in the middle of it inside the drain hole to wire tie the Transducer to.
Excuse the rough cut of the plastic drain threads, I do not have a picture of the finished version of this install. The Scotty #268 Float Tube Fish Finder and Transducer Mount allows you to adapt a fishfinder to your float tube or pontoon boat.

Fish Finder and transducer mount adapts your fish finder and transducer to the Cast Mate™ system. This is not likely because the Mariner has a pontoon type hull and the transducer sits well above the pontoon bottoms yet still submerged in the water. Do you have any problems with the propel drive unit getting in the line of sight of the sonar?
Universal mount for transducer and double sided hook and loop for secure mounting included. With this mount you can safely have your fish finder or transducer in your float tube, kayak or pontoon without the fear of it going overboard and in a location for easy viewing. Membership entitles you to a discount on Native Watercraft Accessories purchased through the forum host, Get:Outdoors.
I noticed in your picture where you show the bottom of the Mariner with transducer through the scupper and the propel drive, it looks like the sonar beam could catch the propel drive unit.

Fits or can be adapted to most fishfinder brands including: Lowrance, Eagle, Humminbird and Garmin.
If you are an existing member and have not reset your password since November 2, 2014, please follow the instructions here. West marine sells a wire port that works great for threading the wires thru the kayak to the battery.
It slows the drain rate down from normal but still works well enough when you get too much water on- board.

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