Changing my fish finder...need assistance

My boat (2012 Bayliner 170 OB Fish-N-Ski) originally came with a Garmin FishFinder 140. It's okay for a starter, but I want to upgrade as I know there are better electronics out there(Lowrance Elite-5 HDI). The current one is mounted on the console, with the wiring running under the gunwale, and then through the stern. I can access the wiring under the gunwale, but then can't see the wiring as it disappears behind the battery before exiting the hull.

Has anyone done this before? Is the hole that is already in the stern big enough to fit the plug from the back of the FishFinder 140, or do I have to cut the wire?

Then the more important question is, how to I run my new transducer through the same hole? I really don't want to drill new holes in the boat. I'd much rather use the existing holes and just attach the new transducer where the existing one is now. And I don't want to spend the $500 unless I know that I'm going to be able to make it work.

Any advice or help would be greatly appreciated.

I'm sure it can be done. You might take the boat to a dealer or boat repair shop nearby, let them look at it and offer advice or even a quote to do it. Good luck.

lowrance elite 7 hdi is 550 after the rebate. My boat mechanic mounted mine for 150 dollars

The short answer is yes. Is the hole big enough for the blue lowrance transducer connector? That's something you have to figure out. I believe (if memory serves) it takes at least a 1" diameter hole (maybe 1 1/8") for the blue connector.

Tie a good piece of string (like mason's string or old trotline)on the old transducer wire. Make sure if it's bundled with all the other wires under the gunwale with zip ties that you undo the bundles. Try pulling the wire from the transducer end and see if it can be pulled, if you put a few pounds of pressure on it and it doesn't move, check for more bundle/tie points. When you get the old wire out, use the string you pulled along with it to pull the new wire back to the console. Be sure to seal all the holes with silicon from the old transducer before mounting the new one.

Thanks to all for the replies and advice. Looks like I have a new project, and I can't wait to get a better fish finder.