Anti-fouling paint is needed mostly in coastal, salt-water environments to prevent weeds and barnacles. In fresh water it shouldn't be necessary, espcecially if you go over over the bottom every so often with a kitchen scrubbie. Once you apply bottom paint, you will have a competitive racing disadvantage compared to boats with clean original gel coats, a possible factor in considering resale value.
If any of you readers out there have experience with storing Capris in fresh water, please reply and tell us how it went with your boat. Thanks.
Anit-fouling paint will add weight to your boat and creat a 'not-smooth' surface that will slow your boat down. If you're not planning to race it, then maybe that doesn't matter to you. But if you are, or may one day want to sell it to someone that wants to race it, you don't want to put the paint on there.
I bought a boat with the bottom paint on it with the intention of racing it, and learned the hard way. See what I went through to remove the paint here:
Oh, to answer your original question. Bottom paint will slow your boat down and it will most likely lower its market appeal. As pointed out above, bottom paint is a mess and a pile of hard work to remove. Keep the boat on its trailer or on a float instead of in the water.