Steering Problem?

Last time out for the season and had nothing but trouble this year. Finally boat was running like a top, then after an hour runtime another problem reared its ugly head. The steering became excessively stiff, especially to the right.The hell with it, I was going to get my last run in no matter what.Wife pulled me for about 3 miles but when she picked me up after drop off, she said it took all her strength to turn the boat around.Took over operating and she wasn't kidding, that wheel was stiff at cruising speed and beyond. But at lower speeds was tolerable although not great.Back home and on trailer steering was quite easy but maybe a tad stiff for open air operation. Removed tiller arm and no change in freedom of movement. Manually checked rudder and its very smooth to turn. Now heres my dilemma-in open air the steering stiffness isn't bad and by the same token its not quite good either-what to do?
A little history:
    Boat is a '97 Nki Nautique purchased new
    Has 300 hours of TLC running time
    Never had any noticeable steering problems (Rack Steering)
    Slop in the wheel is about 1 hour as viewed in 12 hour               clock face.(30 degrees?)
    Boat unknowingly had filled with water above cockpit sole during storage (about 3 weeks).
    2nd time out cooling water hose came off and flooded bilge with hot water before noticed.

Now I am wondering why does the wheel turn freely in open air and very stiff in the water (I am aware of prop thrust fighting back at me, but this takes MUCH more effort than it used to!Is it possible that something in the system is binding when under load? I'm kind of at a loss here and not looking to spend $350 for a new cable/rack assembly if not needed.SOS

Bri
Great post on cable replacement.This will help a lot when the time comes.Have a few questions for you-
   Did you remove drivers seat for access to the helm end?
   From what I gathered, the 20 ft. cable required that a new style helm was needed also, did you replace that?
   Looks like my '97 may need drivers seat and two panels removed in that area to gain better access. Probably no big deal to remove. I have the older style cable (smaller cross section). The 19.5' OEM cable is $299. The newer 19.5' cable is $185 and requires a new helm along with it @ $75 for a total of $260. Cheaper, but I don't know if I will have trouble with tilt steering removal. I guess my helm pinion gear condition will determine which way I go.
At this point I am still not sure exactly where the problem lies, but my thinking is that if the steering is somewhat stiff in free air, the resistance or binding must get multiplied under load. As much as I hate to shell out the cash for these parts, its probably the only way out.
Thanks again for the tips!
   

Classic case of worn out cable including denial. Replace and rejoice