My 1984 Bass Tracker came with a 28 pound Minn Kota trolling motor which, at the time,  seemed adequate for the job.  A couple of years ago my father replaced it with a 40 pound Minn Kota which seems really anemic.  It runs fine but just doesn't have as much power as that old 28.

Would it help to replace the old boat wiring?  I am thinking of using my tax rebate this spring to replace the trolling motor with a 55 pound, variable speed MK Maxxum.

It sure wouldn't hurt to upgrade your wiring.

Over time the wire will deteriorate, i would ohm check your wires and see how much resistance you have.  I would also load test your wires if you don't have any resistance.  

The wire itself does not deteriorate per say. If the wire is really old. I am talking 50 years or so the insulation may have rotted and come off. with modern plastic insulation you should not have a problem.

Where you may have an issue is if the connections where not properly protected. The exposed copper could corrode and become week and break. The corrosion can work its way up under the insulation and corrode   the whole wire.

As you increase motor size you are increasing the current it can draw.  When you draw current through the wiring you get a voltage drop.

The heavier the conductor, the less voltage drop you get.

Although the voltage drop in the original wiring may have been acceptable for a smaller motor, the increased current can produce an unacceptable voltage drop.

If the old wiring is 8 or 10 gauge you should replace it with 6 gauge.  If it is a long run from the battery(ies) to the motor, a heavier gauge will help.

The wire itself does not deteriorate per say. If the wire is really old. I am talking 50 years or so the insulation may have rotted and come off. with modern plastic insulation you should not have a problem.

Where you may have an issue is if the connections where not properly protected. The exposed copper could corrode and become week and break. The corrosion can work its way up under the insulation and corrode the whole wire.

And.........you did not mention if you've changed your battery since 1984?

And.........you did not mention if you've changed your battery since 1984?

True, Never thought someone will still be trying to use a battery from 1984.

And.........you did not mention if you've changed your battery since 1984?

Brand new battery last year and I keep it charged with a Dual Pro on-board charger.