Had my Nitro 189 for a few years now and always store it in the winter as well as have it winterized at my local marina. I can't help but wonder if I am missing something. Is this all that's required to maintain my boat? Or are there some tune ups and such that I might also be overlooking?

The boat should take little maintenance.  Cleaning, waxing, etc.  Eventually it may need new carpeting.  You can also inspect the wiring for chaffing and corrosion.  Hinges, hatches, and other hardware should be checked for wear.  Go over all fastenings.

 

It's the motor and its controls including steering that calls for routine maintenance.  When my boat is winterized I have them check the water pump (impeller and housing) for signs of wear.  I also have the fuel filters changed.  All mounting and steering fasteners should be checked to be sure they are tightened to specs.

 

The trailer, if you have one, needs routine annual service, with special attention to the wheel bearings and seals.

 

The folks who winterize your boat should know what periodic services are needed for your motor, boat and trailer.  Preventive maintenance may not be cheap, but it is economical compared to repairing problems that arise due to lack of maintenance.

If you aren't doing these things then you should:  change the lower unit fluid once or twice each year, change the water separating fuel filter once or twice each year, change the impeller at least every 3 years, take the prop off a couple of times each year and look for mono behind it.

Thanks for the tips I am going to call them and see what is all included in their winterization and if they check these things. As far as cleaning goes I am pretty OCD about that, I completely clean it top to bottom after each outing.